HomeMy WebLinkAboutSouthold Demonstration Site Fertilizer and Pesticide Project
SOUTHOLD DEMONSTRATION SITE
New York State Fertilizer
and Pesticide Demonstration Project
August 1983
by
Nancy M. Trautmann
Keith S. Porter
Henry B. F. Hughes
illustrated by Donna Curtin
CENTER FOR ENVIRONMENTAL RESEARCH
468 Hollister Hall
Cornell University
Ithaca, N.Y. 14853
SpODllOr8bip
This project was sponsored by the New York State Department of
Environmental Conservation as part of the Fiscal Year 1981 Ground Water
Management Program Fertilizer and Pesticide Demonstration Project. Funding
was provided by the United States Environmental Protection Agency under
Section Z08 of the Water Pollution Control Act of 197Z. Cornell University
provided matching funds for this grant.
Acknowledgments
Many people have contributed to the field work and review of technical
material over the course of this project. Primary among these were Dale D.
Moyer, Potato Agent for the Suffolk County Cooperative Extension Association,
who provided many hours of assistance and advice, and Robert Schneck, from
the N.Y.S. Department of Environmental Conservation, Region 1, who provided
direction for the project and critical review of each of our draft reports.
In addition, the following people have contributed time and expertise to
the Southold Demonstration Project:
Citizen's Adviso", Committee
Frank Bear
Bud Cybulski
Richard Hilary
Fred Lappe
James Monsell
Frank Murphy
Ruth Oliva
William Ruland
Valeria Scopaz Shaw
Lydia Tortora, Chairperson
COOllerative Extension
Dale Moyer
Daniel Fricke
William Sanok
David Newton
New York State Department of Environmental Conservation
Robert Schneck
C. Thomas Male, m
Other Government AJ;!encies
Aldo Andreoli - Suffolk County Department of Health Services
Tom Martin - Suffolk County Department of Health Services
Sarah Meyland - State Commission on Water Resource Needs of L.L
James Monsell - Greenport Superintendent of Utilities
Frank Murphy - Southold Town Councilman
Supervisor William Pell, In, and Members of the Southold Town Board
ii
Center for Environmental Research
James Holway
James Pike
Steven Pacenka
Mary Jane Heather
Donna Curtin
Gilbert Levine
Carin Rundle
Margaret Neno
Katherine Wilson
Cornell University
Tammo Steenhuis
Ann Lemley
Jeff Wagenet
David Bouldin
Joseph Sieczka
Arthur Bing
Hi
m.
IV.
V.
Table of Contents
~
Acknowledgments
List of Figures
List of Tables
L
Introduction
1
Regional Context for tbis Study
Study Area Description
Hydrogeologic Description
Southold's Ground-Water Problems
Objectives and Limitations of This Study
1
1
2
3
4
n.
An Introduction to tbe Water and Land Resource
Analysis System
7
The W ALRAS Process
Interpretation of W ALRAS Results
W ALRAS Applied to Southold
Climate Data
SoU Data
Land Use Data
Land Management Data
7
8
10
11
11
11
12
Effects of Housing Development on Ground-Water
Quality
13
Lawn Fertilization Rates
Housing Densities
Cluster vs. Sprawl
Potential Contamination by Organic Chemicals
13
15
19
22
Effects of Potato Farming on Ground-Water Quality
29
Potato Fertilization Rates
Z9
31
34
Split Applications
Effects of Heavy Spring Rains
Economic Consequences of Various Fertilization
Practices
35
Potato Pest Management
36
Effects of Otber Land Uses on Ground-Water Quality
41
Existing Land Uses
Possible Future Land Uses
41
41
iv
VL
VII.
vm.
IX.
Table of Contents {continued}
Aldicarb Contamination of Southold's Ground Water
Aldicarb Use in Southold
Depot Lane Transect
Aldicarb Simulation
Pesticide Screening to Prevent Ground-Water Contamination
The Budget Approach
Building Mathematical Models into the Pesticide
Registration Process
Guiding Field Investigations
Improving Budget Estimates During Field Work
Conclusions and Recommendations
Postscript
APPENDICES
A. Potato Pest Management on Long Island
B. Input Data and Assumptions
C. Turf Nitrogen Simulations
D. Potato Nitrogen Simulations
E. Glossary and Abbreviations
v
Page
47
47
47
47
55
55
56
57
61
63
71
List of FilZlU'es
1-1. Distribution of aldicarb contamination of ground water in Southold,
N.Y.
II-I. Root zone, unsaturated and saturated zones
II-Z. Movement of nitrate to and through the ground water
m-l. Nitrogen concentrations of recharge to ground water from various
lawn fertilization rates
m-z. The effect of housing density on nitrate concentrations leaching to
ground water in Southold, N.Y.
m-3. Simulated nitrate leaching concentrations from a range of housing
densities and lawn fertilization rates.
m-4. Subarea of the Town of Southold, Long Island, N.Y.
m-5. The effect of clustered development on the nitrate concentration of
recharge water
m-6. The effect of various clustering options on nitrate concentratio'!lS
leaching to ground water for a subarea of Southold, N.Y.
m-7. Effect of land uses on ground-water quality
m-8. Four Long Island communities tested for contamination of ground
water by organic chemicals
m-9. Housing density compared with organic chemical contamination of
ground water in four Long Island communities
IV-I. The effects of potato fertilization rates on nitrate concentrations
leaching to ground water for two soil types in Southold, N.Y.
IV-Z. Results of field experiments carried out from 1956 to 1978 at the
L.LH.R.L. on yields of Katahdin potatoes at various fertilization
rates
IV-3. Comparison of nitrate leaching from heavy fertilization at planting
vs. lighter fertilization with split application
IV-4 Effects of split application of fertilizer on simulated nitrate
concentrations leaching to ground water from potato fields in
Southold, N.Y.
IV-5. Effects of split applications of fertilizer on simulated tuber nitrogen
content in Southold, N.Y.
vi
IV-6.
IV-7.
V-I.
V-z.
V-3.
V-4.
VI-l.
VI-Z.
VI-3.
VII-I.
VII-Z.
VII-3.
VII-4.
VII-S.
List of Fi~es (continued)
Effects of heavy spring rain on nitrogen lost from potato fields grown
on Riverhead and Haven solls.
Changes in population and acreages of farm land and land used for
potato production in the Town of Southold, N.Y. from 1930 to 1980
Land uses in the Depot Lane transect area, Southold, N.Y.
Soil types in the Depot Lane transect area, Southold, N.Y.
Results of nitrate simulations in the Depot Lane transect area,
Southold, N.Y.
Nitrate concentrations in ground water along the Depot Lane
transect, Southold, N.Y.
Aldicarb concentrations measured in wells along the Depot Lane
transect, Southold, N.Y.
Areas used for aldicarb analysis along the Depot Lane transect,
Southold, N.Y.
Simulated aldicarb plumes along the Depot Lane transect, Southold,
N.Y.
Generic model of pesticide behavior in the root zone
Integration of mathematical models into the pesticide evaluation
process
Sensitivity of annual aldicarb mass balances to decomposition and
plant uptake parameters
Relationships among impact limits, uncertainties, and decisions about
pesticides for potential use in Southold, N.Y.
Proposed review procedure for pesticides, assuming the null
hypothesis that the pesticide will not violate ground-water criteria or
standards
-
A-I. An aphid on the leaf of a hybrid potato plant that produces a sticky
black gum, trapping insects and causing them to starve to death.
A-Z. A potato showing the effects of the potato scab disease.
A-3. Barnyard grass (Echinochloa Crus-Galli) a common weed in potato
fields in Southold, N.Y.
vii
List of Fi2U1'es (continued)
A-4. Nutsedge (Cyperus Rotudus), a common weed in potato fields in
Southold, N.Y.
A-5. Bindweed (Convolvulus Arvensis), a weed commonly found along
roadsides which also invades potato fields in Southold, N.Y.
C-I. Comparison of field data with WALRAS simulations of nitrogen
uptake by turf
C-Z. Twelve Pines study area
D-l. Comparison of WALRAS simulation results with field measurements
of the nitrogen content of potato tubers. Tbe field experiments were
carried out by the Long Island Horticultural Research Laboratory
D-Z. Sensitivity analysis for the W ALRAS potato simulations.
viii
U-l.
U-z.
m-l.
m-z.
m-3.
m-4.
m-5.
List of Tables
The relationship between annual average nitrate concentrations and
the probability that the standard will not be violated by individual
samples
New York State standards for water quality for contaminants
considered in this report
Rates and dates of lawn fertilization used in W ALRAS simulations
Assumptions related to nitrogen inputs for W ALRAS simulations of
residential development
Comparison of Southold housing densities with the average
percentage of time that the 10 mg/l nitrate standard can be expected
to be exceeded
Description of organic chemicals found in ground water underlying
residential communities on Long Island, New York
Number of wells affected by organic chemical contamination in
Wading River, Rocky Point, Mastic and Mastic Beach
m-6. Comparison of average housing density with organic chemical and
nitrogen contamination of ground water in four Long Island
communities
IV-I.
IV-Z.
IV-3.
V-I.
VI-I.
VI-Z.
VI-3
VU-l.
Simulated values for nitrogen leached and nitrogen content of
potatoes grown on Riverhead and Haven soils.
Economic consideration of potato fertilization rates.
Per acre yield of potatoes on L.L and in U.S., 1955-1980
Simulated nitrate leaching concentrations for various land uses in
Southold, N.Y.
Aldicarb use on fields along the Depot Lane transect, 1975 to 1979
Simulation results showing dates that aldicarb will reach ground
water, and its average concentrations in ground water below the
Depot Lane transect in Southold, N.Y.
Laboratory data on half-lifes (in days) of aldicarb and its degradation
products in water at various pH's and temperatures.
Budget corresponding to model in Figure VU-l
ix
List of Tables (continued)
VII-Z.
Minimal data requirements for W ALRAS regional evaluation of
pesticide movement and fate
B-1.
Summary of assumptions relating to each land use type.
B-Z.
Summary of assumptions relating to land cover types.
B-3. Rates and timings of organic fertilizer (kg N/ha) , Southold
Demonstration Site.
B-4. Rates and timings of organic slow-release fertilizer (kg N/ha) ,
Southold Demonstration Site.
B-5. Irrigation amounts and timings, Southold Demonstration Site.
B-6. Nitrogen uptake curves (expressed as percentages), Southold
Demonstration Site.
B-7. Plant harvest fractions and dates (expressed as percentages),
Southold Demonstration Site.
C-l. Rates and dates of fertilizer N applied to turf (Selleck and others,
1980)
C-Z. Basic data for the Twelve Pines subdivision
C-3. Simulated nitrogen in recharge, Twelve Pines area
C-4. Summary of Twelve Pines well data
C-5. Comparison of observed and simulated nitrogen concentrations in
ground water, Twelve Pines subdivision
C-6. Summary of sensitivity analysis of the W ALRAS root zone water and
nitrogen simulations for turf for conditions representing
Southampton, N.Y.
D-I. Fertilization rates and timings for L.LH.R.L. experiments on
Katahdin potatoes, 197Z-1975.
D-Z. Comparison of field and simulation (W ALRAS) results for nitrogen
content of harvested potatoes
x
Chapter I
INTRODUCTION
Regional Context for Tbia Study
Ground water is the primary source
of drinking water for approximately half
the population of the United States. On
Long Island, ground water percolates
through the soil and is stored in permeable
geological formations called aquifers.
The Long Island aquifer system is one of
only seven in the country that has been
designated by the U.S. Environmental
Protection Agency as .sole source," and it
provides one hundred percent of the
drinking water for the 1.3 million residents
of Suffolk County, an area encompassing
the eastern two-thirds of the Island.
Traditionally, it has been assumed
that ground-water quality is protected by
the filtering action of soil as the water
percolates downward through the ground.
In recent years, however, widespread
discoveries of ground-water contam-
ination have shown this assumption to be
unfounded. Housing, industry,
agriculture, and commercial land uses can
pollute underlying ground water, as can
more obvious sources such as landfills or
toxic waste dumps.
This report addresses ground-water
contamination problems that have been
identified in the Town of Southold, at the
eastern end of Long Island, New York.
Although Southold relies exclusively on
ground water for its drinking water
supplies, many of the area's drinking
water wells exceed standards for nitrate
or guideline values for certain
agricultural pesticides. Synthetic organic
chemicals used in industrial, commercial,
and household products also have been
detected in some of the Town's wells.
The key to restoring and protecting the
quality of Southold's aquifer is prevention
of contamination of the recharge water
that continuously replenishes the ground
water supply. It is for this reason that
decisions regarding the many land uses
and human activities in Southold need to
be made based on an understanding of how
they will affect the quality of ground-
water recharge supplies.
In order to demonstrate basic
procedures of ground-water resource
management, the New York State
Department of Environmental
Conservation and the U.S. Environmental
Protection Agency funded Cornell
University's Center for Environmental
Research to work with four New York
communities on ways of protecting
ground-water recharge from nitrate and
pesticide pollution. This report describes
the work done in Southold, N.Y.,
evaluating existing contamination sources
and means of reducing their impact on
ground water. Although the. results
presented here are specific to the
Southold site, the technical methods used
can also be applied in other areas with
similar ground-water concerns.
The Southold Study ~
Southold is a scenic rural town
encompassing the North Fork at the
eastern end of Long Island, N.Y. Bounded
on three sides by salt water, it is
characterized by coastal views and large
stretches of land devoted to farming.
Agriculture, fishing, and support of
seasonal residents and tourists form the
basis for the town's economy. Southold's
year-round population was 19,000 in 1980,
up 14 percent from a decade earlier, and
the seasonal population has been
expanding as well. The effects of this
increased residential development on the
town's open space amenities and ground-.
water quality are issues of growing
concern in Southold.
Ever since the invention of the
mechanical potato digger in the 1880's,
potatoes have been Southold's major crop,
with approximately 5,500 acres currently
devoted to potato fields. Close to one
quarter of LODg Island's potato crop is
grown in Southold, where potato farming
is a ten million dollar per year indus.try.
Related industries including sales of
agricultural equipment and supplies also
are important to the North Fork economy.
The monoculture nature of potato
farming in Southold has led to severe
pressure by the Colorado potato beetle,
which has developed resistance over the
years to many of the chemicals used for
its control. In 1975, a new pesticide
called aldicarb (brand name Temik)
proved to be highly effective in
controlling the beetle populations. This
chemical was used by Southold's potato
farmers through 1979, when it was
withdrawn from sale on LODg Island
because of its discovery in the area's
ground water.
Because of the current difficulty in
combating the Colorado potato beetle and
the marginal economics of potato farming
in recent years, many Southold farmers
have diversified their crops or are
contemplating doing so in the future.
Cabbage, cauliflower, and sweet corn are
the most common vegetable crops, and
occasionally these are grown in rotation
with potatoes. Although not a major
percentage of the agricultural market,
fruits including peaches, apples, pears,
table grapes, cherries, melons, and berries
also are grown in Southold. The area's
newest agricultural crop is wine grapes,
with the first vineyard started in 1973.
The substantial investment involved and
the three year delay in grape production
while a new vineyard matures have,
however, thwarted many farmers from
converting to this crop.
----
2
Hydrogeologic Description
All of the fresh ground water stored
beneath Southold originates from
precipitation which falls within its
boundaries. Approximately 50 percent of
the precipitation (total yearly
precipitation averages 44 inches)
recharges under natural conditions. Fresh
ground water exists only to a maximum of
about ZOO feet, and is underlain by salt
water.
Water which falls on the
hydrogeologic center of the North Fork
(the ground-water divide) moves
vertically downward in the ground-water
system. North and south of the divide, an
increasing horizontal component is
evident until, at some point, ground water
moves horizontally. Beyond that point,
closer to the coastline, ground water
moves horizontally and discharges to the
various creeks and bays to the south, or to
Long Island Sound to the north.
A sense of the time involved in the
movement of ground water through this
hydrogeologic system is important. It is
estimated 'that water recharging near the
ground-water divide will remain in the
aquifer for about 100 years. This
residence time is shorter for water
recharging closer to the shorelines.
The flow of ground water through
the unsaturated and saturated zone is
dynamic in nature, although flow
velocities are quite slow. The rate of
downward flow through the unsaturated
zone is dependent on precipitation rates,
and is on the order of 10 feet per year.
Downward velocities in the saturated
zone beneath the ground water divide are
approximately 0.1 ft/day, with horizontal
flows estimated as O.Z to 0.4 ft/day at
locations towards the shorelines (Baier
and Robbins, 198Z). These low velocities
result in contamination remaining within
the aquifer for extended periods, while
chemicals are carried through the aquifer
until eventually "flushing" to surrounding
salty waters.
Little mlxlDg occurs within the
aquifer system. Therefore, contamination
remains in somewhat distinct plumes
which travel through the aquifer,
eventually (many years later) discharging
from the fresh ground-water system.
New waters are continuously introduced
through recharge. Therefore, the future
ground-water quality is dependent on the
quality of recharge. If recharge waters
are of a high quality over an extended
period of time, the aquifer will eventually
be restored.
Under natural conditions the aquifer
underlying Southold was filled with
pristine ground water. Over the years,
various land uses within the Town resulted
in contamination of recharge water. A
major portion of the aquifer has gradually
been filled with this contaminated water,
and it is now observed at many of the
Town's drinking water wells.
The North Fork Water Supply Plan,
formulated by Suffolk County, has
recommended treatment for private and
public water supplies which are adversely
affected by pesticide or nitrate
contamination. It is acknowledged that
this is a "bandaid" type solution to the
water supply problem. The long term
solution involves controlling the
multiplicity of sources of all
contaminants, including nitrate, various
pesticides, and the ever-growing list of
organic chemicals which are utilized by
industry, commerce, and private
households.
The work conducted under the
Southold Demonstration Site portion of
the New York State Fertilizer/Pesticide
Project considers some important current
sources of contamination. Under the
funding agreement with EPA, this project
was required to investigate sources of
pesticide and fertilizer contamination.
The scope was expanded somewhat to
include other sources of nitrate
associated with lawn fertilization (runoff
from impervious surfaces, natural
vegetation, and domestic sewage).
Overall ground-water pollution source
3
control must address these and numerous
other contaminant sources and
constituents.
Sonthold's Ground-Water Problems
Southold's ground water is
particularly susceptible to contamination
for a number of reasons. The Town's soils
are highly permeable, allowing recharge
waters and associated contaminants to
leach rapidly downward. The relatively
low topography of the North Fork and
resultant shallow depth to the water table
minimize the time required for recharge
to reach the ground water. The physical
dimensions of the fresh ground-water
reservoir are quite limited, making
contamination problems particularly
serious. Fresh water exists only in
relatively thin lenses (maximum thickness
of about 200 ft) beneath the landforms of
Southold (Baier and Robbins, 1982).
Ground water is the only source of
potable water to the approximately
20,000 residents of Southold and the large
number of summer visitors. In addition,
agriculture, which represents a major
portion of the economy, relies on fresh
ground water for irrigation purposes. Due
to this sole reliance on ground water and
the lack of alternative sources, ground-
water protection needs to be of utmost
priority in Southold.
In recent years, a number of
problems ha.ve arisen with the area's
ground-water quality. A brief summary
of existing problems follows:
. Three (14%) of the 21
Suffolk County test wells in
Southold have average
nitrate concentrations
higher than 10 mg/l, the
drinking water standard.
Nine of these wells, or 43
percent, have had at least
one sample exceeding 10
mg/l nitrate, indicating that
the problem is not an
isolated one.
. 897 (16%) of the 5,784
Southold wells tested by the
Suffolk County Department
of Health Services exceeded
the 7 ppb drinking water
guideline for aldicarb, a
pesticide used on potato
farms from 1975 to 1979,
and another 763 (13%) had
detectable concentrations
below this guideline. Figure
1-1 shows the distribution of
aldicarb contamination of
ground water in Southold.
. Carbofuran, another agri-
cultural pesticide, was
fOUll;d in 598 (30%) of the
1986 wells sampled in the
Town of Southold, with 123
(6%) of these wells
exceeding the 15 ppb
drinking water guideline.
. Trace organic compounds
have been detected in 3
(15%) of the Town's 20
standard observation wells.
These wells are part of a
ne'twrork installed by the
SUffolk County Department
of Health Services for
various monitoring purposes.
. Leachate from the Southold
landfill has caused standards
for selenium, manganese,
and iron to be exceeded in
water obtained from
downgradient wells.
. Salt water intrusion and up-
coning has become a
problem in some shoreline
areas due to excessive
ground-water withdrawals.
Objectives aDd LimitatiollB of this Study
The Southold Demonstration Project
has focused on nitrate and aldicarb, the
4
two foremost contaminants of Southold's
ground water. The project has sought to
identify means of reducing nitrate
concentrations in ground water through
evaluation of the effects of various land
uses and management practices on nitrate
concentrations in recharge water. Since
the primary sources of nitrate leaching
are fertilizers and septic systems, the
effects of various agricultural and
residential fertilization practices and a
range of housiDg densities have been
evaluated.
Aldicarb differs from nitrates in
that it is no longer used on Long Island.
The question of concern is therefore not
how to manage aldicarb applications, but
how long it will take for ground-water
concentrations to diminish to acceptable
levels. By tracking the attenuation and
movement of aldicarb from the soil
surface to and through the ground water,
estimates can be made of how long it will
present a problem in Southold.
A technique is presented for
screening of pesticides prior to use and
for identification of those most likely to
leach to ground water. Such a procedure
could be used in the pesticide registration
procedure as a means of reducing possible
new ground-water contamination by
pesticides.
Because this project focused on
fertilizers and pesticides, ground-water
contamination by sources not directly
related to housing or agriculture have not
been addressed (e.g. landfill, industrial
and commercial sources). However, since
potential organic chemical contamination
is an important consideration in planning
residential densiti~s, a summary of
existing data Qn organic chemicals found
in LODg Island ground water has been
included.
Water quantity issues such as
overpumping and salt water intrusion are
also ignored in this report, but will need
to be considered in conjunction with the
f
1
LEGEND
D < 1.4 PP8
~1.4
1":"':"]36
..........
:,;~::.:::::. .
~ 7.0 - 14.0
.14.0 - 112.0
3.6 PP8
7.0 PP8
PP8
PP8
(Concentrations In Parts Per IIlIIionI
,.... .
I 0
.
2
!-
FIGURE 1-1, DISTRIBUTION OF ALDICARB CONTAMINATION OF GROUND WATER IN
SOUTHOLD. N.Y.
recharge quality data presented here
when land use decisions are made in
Southold.
All of the calculations presented in
this report are site-specific, and
extrapolation of the specific simulation
renlts to other areas may be misleading.
The nitrate recharge values are
influenced greatly by soil type, weather
patterns, and a number of land
management factors which have been
made as specific as possible to the
Southold study sites. The aldicarb
calculations were performed for a narrow
transect across the N.orth Fork and are
dependent on the a.ldicarb application
schedules, water table depths, and
6
ground-water flow patterns for that
particular site.
This report provides information
useful for land use planning, agricultural
and turf management practices, public
education efforts, and continued research
aimed at restoring and. protecting
Southold's ground-water quality. Specific
recommendations are presented in
Chapter vm. In addition, the work
conducted in the Town of Southold and
presented in this report demonstrates the
computer modelling capabilities
developed by Cornell University's Center
for Environmental Research. These
methodologies are transferable outside of
the specific study area, provided that
accurate site specific data are available
for use in the model.
7
Chapter n
AN INTRODUCTION TO THE WATER AND LAND RESOURCE
ANALYSIS SYSTEM
The purpose of the Water and Land
Resource Analysis System (W ALRAS) is to
make it possible to compile available data
on water and dissolved chemicals and to
perform the calculations necessary to
evaluate existing and future sources of
ground-water contamination. Use of
W ALRAS for simulation of water and
contaminant movement to and through
the ground water relies on site-specific
data for climate, soil types, land uses, and
management practices.
The W ALRAS Process
The W ALRAS process consists of
deriving a site-specific budget for water,
taking into account precipitation,
evaporation, plant uptake, runoff, and
leaching, then using this water budget for
calculation of move.ment of the
contaminant of interest, in this case
either nitrate or aldicarb.
W ALRAS simulations consist of
calculation of water and contaminant
movement through three zones: (1) the
root zone, characterized by presence of
plant roots, organic matter, and
microorganisms, (2) the unsaturated zone,
with less organic matter and little or no
microbial activity, and (3) the saturated
zone, or ground-water layer (Figure n-l),
where both biological and chemical
activity are generally believed to be low.
Movement of chemicals downwards
from the root zone depends on how
soluble they are in water, how quickly
they break down in soil, and how strongly
they adsorb to soil particles. Both nitrate
and aldicarb are highly soluble and only
very weakly adsorbed to soil particles, so
both travel freely from the root zone with
recharge and irrigation water.
Given the aerobic condition in the
Long Island soil-water system, it is
believed that nitrate concentrations
diminish little if at all after the nitrogen
leaves the root zone. Therefore,
W ALRAS simulations of nitrate
contamination can be confined to this one
zone with the assumption that whatever
nitrate leaves the root zone will
eventually reach the water table (Figure
n-2).
Within the root zone, mass balance
equations are used to represent the
interactions between the various organic
and inorganic forms of nitrogen in the soil
and plant biomass. Inputs to the system
include nitrogen contained in fertilizers,
precipitation, and animal wastes, and
outputs include gaseous losses, runoff, and
leaching out of the root zone. Uptake and
fixation of nitrogen by plants provide
temporary storage, with outputs when the
plan.ts die or are harvested.
Unlike nitrate, aldicarb may
degrade within the unsaturated and
saturated zones, so all three zones need
to be included in the simulations. As with
nitrate, the first step is to create a water
budget, in this case tracing water
movement all the way to and through the
aquifer. Next, the pesticide movement is
simulated, based on water flow and how
strongly the chemical is adsorbed to soil
particles. Finally, degradation rates are
calculated for aldicarb in each of the
three zones.
The highest breakdown of aldicarb
occurs within the root zone, near or at
the soil surface. As microbial activity
decreases with depth through the soil
profile, degradation of aldicarb becomes
slower. Since field and laboratory studies
8
FIGURE 11-1. R00T ZONE. UNSATURATED AND SATURATED ZONES.
CONTAIIINANT
APPLI'CAHON I
W~TER INFLUX. INCLUDING:
RMN. SNOWMELT. IRRIGA'HON
AND OVERLANO FLOW
. ROOT ZONE
UNSATURATED ZONE
SATURATED ZONE
have estimated a wide range of
degradation rates, this is an area of
uncertainty in our simulations and is
represented by the range of results
presented in Chapter VI.
Interpretation of W ALRAS Raults
Results from WALRAS simulations
are usually summarized as annual
averages, not upper limits for
contaminant concentrations. An annual
average of 10 mg/l nitrate leaching to
ground water means that the
concentration leached would be expected
to be higher than 10 mg/l about fifty
percent of the time and lower than this
value the other fifty percent. In order to
prevent the 10 mgll drinking water
EVAPOTRANSPIRATION
SURF ACE
RUNOFF
Sandy 10... to .Clty 10Gllt aofl.
Ore.t..t microbCal actCon.
Significant Influanca by
plant..
Uaually COGr,er material than
root zon.. V.rUcal,
downward water mov.ment.
t'mit.d b'ologlcal activity.
.val.r'al .hn'lar to
un.'ahtrat'd zon.. Dominantly
Hi"" z,...'Il'" ....r ...---n.l.
......'t;... ...i.,......'. ...~t,"v:, li)'_
,
standard from being exceeded this
frequently, an average level substantially
lower than the standard should be used for
planning purposes.
Statistical analysis of Nassau
County well data has been used to
compare mean nitrate concentrations of
regions four square miles in size with the
percentage of samples exceeding the 10
mg/l drinking water standard (Porter,
198Z). This analysis showed that when the
mean nitrate concentration was 6 mg/l,
the 10 mg/l standard was exceeded by ten
percent of the samples. Similarly, Table
ll-l shows the relationship between annual
average nitrate concentrations and the
probability of individual samples not
exceeding the 10 mg/l standard.
Table n-l
The Relationship Between Annual Average
Nitrate Concentrations and the
Probability that the Standard Will Not Be
Violated by Individual samples
Probability of
Not Exceeding
10 mllll
50%
90%
99%
99.9%
Average Nitrate
Concentration
10 mg/l
6 mg/l
3 mg/l
Z mg/l
In planning future land uses for
Southold, an explicit plann;ng standard for
nitrate will need to be chosen which
incorporates the margin of safety most
acceptable to the Town. For example, if
it is decided that ten percent of the time
9
the 10 mg/l standard can 'be exceeded by
individual samples, then a planning
standard of 6 mg/l would be used.
Similarly, allowing samples to exceed 10
mg/l only one pel'cent of the time would
require lowering the planning standard to
3 mg/l. Once the average concentration
has been specified, the annual loading
level compatible with the average
concentration can easily be determined.
This level cm then be applied in
reviewing individual sources of nitrogen.
Many chemicals other than nitrate
need to be considered in planning for
protection of Southold's ground-water
quality. Because of the lack of extensive
well data for each of these chemicals,
however, exact plann;ng standards such as
the one for nitrate cannot be derived.
Protection of ground water from
agricultural pesticides can be provided
through thorough screening of proposed
chemicals, as discussed in Chapter vn.
The likelihood of ground-water
contamination by organic chemicals is
fl_ 11-2. _ Of MUM'!'! TO _ _ TIll S_ WATER.
related to housing density, but cannot be
accurately quantified with existing data.
The W ALRAS simulations for nitrate can
provide a base for planning decisions in
Southold but should be supplemented with
consideration of the potential for
contamination by other chemicals as well.
The New York State Department of
Health drinking water standards and the
New York State Department of
10
Environmental Conservation Effluent
Standards for discharges to ground water
can serve as a starting point for
development of criteria (see Table II-Z).
As an interim planning guideline it would
appear prudent to adopt loading levels for
organic contaminants which correspond to
lilS.s than 50 percent of the maximum
level specified for the contaminant in
drinking water.
Table II-Z
New York State Standards for Water Quality for
Contaminants Considered in
This Report
NYSDOH
Health
Standard or
Guideline
Contaminant
NYS DEC
Effluent
Standard
(if more strinR;ent *)
Nitrate
Aldicarb
Benzene
Carbofuran
Carbon Tetrachloride
Chlorodibromomethane
Chloroform
Methylene Chloride
Tetrachloroethylene
Toluene
1,1,1 Trichloroethane
Trichloroethylene
Xylene
10 mg/l
7 ug/l
5 ug/l
15 ug/l
50 ug/l
50 ug/l
50 ug/l
50 ug/l
50 ug/l
50 ug/l
50 ug/l
50 ug/l
50 ug/l
0.35 ug/l
not detectable
5 ug/l
10 ug/l
* The effluent standard is defined to be the health standard unless a more
stringent standard is specified.
The drinking water standards and
guidelines apply to public water supply
systems and were established to protect
human health. The D.E.C. effluent
standards apply to discharges to aquifers
which are best suited to providing
drinking water. Domestic on-site waste
water disposal systems and agricultural
practices are exempt from the effluent
standards provided that these activities
do not preclude the use of the ground
water for drinking.
W ALR.AS Applied to Southold
In Southold, one of the major
ground-water problems is nitrate
contamination, and it is desirable to know
what the main sources of nitrogen are and
how these sources can be managed in
order to protect ground-water quality.
W ALRAS provides an organized means of
computing the inputs and outputs of water
and nitrogen from the land surface, with a
focus on calculating the nitrate
concentrations in ground-water recharge
under a given set of environmental
conditions and management practices.
Another major ground-water
problem in Southold is contamination by
aldicarb, a pesticide widely used on
potato fields from 1975 to 1979. Aldicarb
use is now banned on Long Island, so the
objective in this case is not management
of its sources but determination of how
far the contamination will spread and how
long it will last.
Two sites were chosen for W ALRAS
simulations in Southold. The first,
bounded by Reeve's Avenue, Middle Road,
Henry's Lane, and the Long Island Sound,
was used for the analysis of housing
development presented in Chapter Ill.
This site was chosen because it represents
a typical area along Southold's shorelines
where farming is currently the
predominant land use but where pressure
for housing development is now
increasing. The second Southold site, a
transect across the North Fork along
Depot Lane, was used for estimation of
,nitrate leaching concentrations from a
variety of agricultural crops as well as for
evaluation of aldicarb movement and
attenuation in the ground water (Chapters
V and VI of this report). This site was
chosen because it had recently been used
for a field investigation by the Suffolk
County Department of Health Services
and therefore had detailed well data for
nitrate and aldicarb that were unavailable
at other locations.
The data used in this study are
described below.
CUmate Data
Climate data for Southold were
obtained from the weather station at the
11
Greenport Power House. Average
conditions were obtained by averaging
simulation results for 1976, 1978, and
1980 since these years represent average,
wet, and dry precipitation amounts and
their average approximates the long term
precipitation average at this station. For
W ALRAS calculations, each year is
divided into 30 twelve-day timesteps to
account for seasonal variations in
climate.
Soil Data
In the Southold study areas, there
are three major soil groups: Riverhead
and Haven sandy loams, Carver and
Plymouth sands, and Scio silt loam. The
Riverhead and Haven soils are well
drained and moderately coarse textured.
They make up the largest area of farm
land in Suffolk County and are used
extensively for growing potatoes and
other vegetables. The Carver and
Plymouth sands are excessively drained
and coarse textured. Because fertility is
low and permeability is rapid, these soils
are not as well suited to agriculture but
do make up portions of farm fields in
Southold. Scio silt loam is moderately
wen drained and medium textured. It is
found in small pockets among the Haven
soils. Values used for the hydrologic
properties of these soils are listed in
Appendix B, Table B-1.
Land Use Data
In order to quantify the effects of
existing and future land uses on ground-
water quality at the Depot Lane study
site, land uses were mapped using data
from the Long Island Regional Planning
Board, as well as extensive field checking.
The 15 categories used are defined in
Appendix B, Table B-Z. Residential land
uses were further characterized according
to their associated areas of turf,
unfertilized vegetation, and impervious
land surfaces for the purpose of compiling
the land use effects on the water and
nitrogen budgets. (These percentages are
listed in Apendix B, Table B-3.)
LaDd Management Data
Management practices play a key
role in determining water and chemical
budgets in the root zone. The rate and
timing of fertilizer applications, for
example, determines how much nitrogen
is add.ed to the soil and whether it is
present and available at a time when
plants can use it. For each crop
simulated, we estimated average
fertilization practices by consulting with
the Suffolk County Cooperative Extension
Association, an agency that makes local
fertilizer recommendations and which
works closely with Southold farmers.
12
These fertilization rates and schedules
are shown in Appendix B, Table B-4.
Typical planting and harvest dates for
each' crop appear in Appendix B, Table B-
5. Between planting and harvest,
estimates must be made of the rate of
plaat growth as it relates to the ability of
each crop to capture available soil
nitrogen (Appendix B, Table B-6).
Wherever possible, field data have been
used to obtain these numbers. For crops
where no data are available, estimates of
nitrogen uptake rates have been made
based on physical growth curves.
13
Chapter m
EFFECTS OF HOUSING DEVELOPMENT ON GROUND-WATER QUALITY
Housing development in Southold
needs to be carefully planned for
protection of ground-water quality.
Residential septic systems arid lawn
fertilizers can be major sources of nitrate
nitrogen, and household organic chemicals
also can contaminate underlying ground
water. Increased housing density
will usually increase contamination.
Other land uses associated with
residential development will also add to
the potential sources of ground-water
pollution. Low housing density combined
with restraint in lawn fertilization will
limit the impacts associated with housing
development.
Lawn Fertilization Rates
Suffolk County Cooperative
Ex.tension recommends fertilization of
home lawns with either 1.0, Z.O, or 3.0 Ib
NflOOO sq. ft., depending on type of grass
and the degree of greenness desired by
the homeowner (Suffolk County
Cooperative Extension, 1981). A survey
conducted in 1980 by the Cornell
University Center for Environmental
Research found that 45 percent of
Southold's home owners fertilize their
lawns with an average of 2.4 Ib NflOOO sq.
ft.fyr., and the remaining 55 percent USe
no lawn fertilizers at all (Pike et al.,
1980).
Using WALRAS, we simulated the
nitrate leaching concentrations resulting
from use of 0, 1, 2, or 3 Ib Nf1000 sq. ft.
on home lawns, with 50 percent of the
grass clippings removed (Table m-l). In
each case, it was assumed that half of the
fertilizer was in fast-release form, and
the remaining half was in a slow-release
organic form providing nitrogen later in
the growing season.
As shown in Figure m-l, nitrate
leaching steadily increases with
increasing doses of fertilizer nitrogen,
and rates higher than 2 Ib NflOOO sq. ft.
result in leachate concentrations
exceeding the 10 mg/l drinking water
standard in ground water immediately
underlying the lawn.
14
12
,
rl0
i a
I a
i .
2
o
o 1 2 3
F.tllI.. Applied lib N/1ooo Iq. 't.1
FIGURE
lII-I. NITROGEN CONCENTRATIONS OF RECHARGE
TO GROUND WATER FROM VARIOUS LAWN
FERTILIZATION RATES.
These results are confirmed by field
experiments conducted at the Long Island
Horticultural Research Laboratory (Snow,
1976). A blend of four Kentucky
Bluegrass varieties was planted in the
spring of 1974 and fertilized at rates of 0,
2,4, and 8 Ibs.flOOO sq. ft. divided into 0,
1, 2, 4, or 8 applications per year for the
following two summers. During the
second summer, an average of 25 percent
of the applied nitrogen was leached from
the root zone when the grass clippings
14
Table m-l. Rates and dates of lawn fertilization used in W ALRAS simulations
Total N
Applied
Per Year
(1b N/IOOO
sq. ft..)
0.0
Seurce
19&0 Survey
of Town
of Southold*
1.0
Suffolk
County
C.E.
re.commendation
Z.O
Suffolk
County
C.E.
recommendation
Z.4
19'80 Survey
o,f Tow.n
of Southold*
3.0
Suffolk
C01m1:y
C.E.
recommendation
Fertilization
Rate Per
Application
(lb N/lOOO
sq. ft..)
0.0
Dates of
Application
N.A.
1.0
Sept. 10
1.0
May 13
Sept. 10
l.Z
May 1
Sept. 10
1.0
May 13
Sept. 10
Nov. Zl
* A 1980 Survey of the Town of Southold showed 55% of the homeowners using
no lawn fertilizers and the remaining 45% using an average of Z.4 Ib N/lOOO
sq. ft./yr.
were removed, and 50 percent when the
clippings were left in place. As the turf
became more mature, the leaching rates
were expected to increase further still
because the net amount of nitrogen
incorporated into the plant biomass each
summer would diminish as the grass
reached an equilibrium in growth.
It was concluded that when clippings
are left in place, turf fertilization at
rates higher than Z lb/lOOO sq. ft./yr. is
likely to result in ground-water recharge
concentrations exceeding 10 mg/l.
Removal of grass clippings reduces the
amount of nitrate leaching from the lawn,
but the clippings will still cause nitrate
leaching in the landfill or wherever they
are disposed. A better solution is to use
them as mulch or compost to provide
nitrogen to other plants and reduce the
need for other fertilizers.
Analysis of aerial photographs (Pike
et al., 1980) has shown that the portion of
each lot covered by turf varies according
to the lot size. With one-acre or larger
lots in the Town of Riverhead, for
example, an average of only 16 percent. of
the area is covered by turf and 6Z percent
is devoted to other types of vegetation,
presumed in our simulations to be
unfertilized. To whatever extent
fertilizer is used on gardens, shrubs, or
other plantings other than lawns, our
leaching rates in these simulations would
be underestimated. With l/Z- to 1/4-acre
lots, the turf increases to an average of
45 percent of the area and unfertilized
vegetation drops to only 17 percent.
Since water percolating through
unfertilized areas leaches much less
nitrogen than that draining turf, the
effects of lawns on ground-water quality
depend on the total area they cover as
well as on lawn fertilization rates. The
following section takes these varying
amounts of turf into account in
calculations of the ni tra te leaching
concentrations produced by various
densities of residential development.
HOWling DeDBities
Southold currently is zoned at two
acres per house. The Town allows the
total number of permissible houses to be
clustered into 50 percent of the land area.
For example, a developer who has 100
acres of land could build 50 houses, either
with two-acre lots spread evenly across
the development, or with one-acre lots
clustered onto half the land and the
remaining 50 acres left as open space. *
The Town Planning Board is considering
allowing the houses to be clustered even
closer together, into 35 percent of the
total land area, for a net housing density
of 1.4 houses/acre.
15
The nitrate leaching concentrations
produced by various housing densities in
Southold are shown in Figure m-z, with
assumptions as outlined in Table m-z. * *
As housmg density increases, nitrate
concentrations also increase, largely
because of the higher amounts of
wastewater generated. The contributions
from on-site wastewater disposal rise in
proportion to the number of people living
in the area, and make up a progressively
larger portion of the total nitrogen
leached as the density of housing
increases. Inputs from lawn fertilization,
the other major nitrogen source, also
increase as residential density increases
up to 3 houses/acre, after which the
smaller lot sizes lead to less area in turf
(Table m-Z).
The amount of lawn fertilization has
a large effect on the nitrate leaching
concentrations, as shown in Figure m-3.
At a housing density of one house per
acre, for example, the concentration
ranges from Z.7 to 5.4 mg/l as lawn
fertilization is increased from 0 to 3 Ib
N/IOOO sq. ft. For the housing density
calculations in this report, it was assumed
that 45% of the lawns are fertilized with
Z.4 Ib N/1000 sq. ft. and that the
remaining 55% are unfertilized. This is
an approximation for Southold, based on a
1980 survey of 53 households in the town
(Pike et al., 1980).
Determination of the maximum
density of housing below which ground-
water quality in Southold would be
preserved depends in part on the decision
regarding safety margins. Table m-3
compares housing densities in Southold
with the percentages of time that each
would be expected to produce leaching
concentrations higher than the 10 mg/l
* Actually, only 40 houses could be built under the clustering option because
ZO% of the land would need to be reserved for roads, curbing, parking, etc.
**All housing density simulations were based on year-round rather than
seasonal occupancy.
18
standard. Determination of which of
these levels are acceptable is a public
policy decision that should be made by the
Town before long-range land use plans are
completed. The values represented in
Figure m-z and Table m-3 are based on
the specific set of assumptions listed in
Table m-z. If variables such as the
percentage of each lot maintained as turf
or the average amount of fertilizer used
on lawns were to .change, then the
W ALRAS calculations would need to be
revised accordingly.
7
D-runoff from Impervtoul lurf..
II-.......Iulled wept.llon
.-turt
.-_0
e
5
-
,
r
-
I ·
o.
...
j
i
z,
,.
o
Houefng DeMity (hoUMIi/acre)
FIGURE [[[-2. THE EFFECT OF HOUSING DENSITY ON NITRATE CONCENTRATIONS
LEACHING TO GROUND WATER IN SOUTHOLD. N.Y."
'THESE DENSITIES ARE INCLUDED BECAUSE THEY ARE USED IN THE FOLLOWING
CLUSTER YS. SPRAWL SECTION OF THIS REPORT.
oOIN THESE SIMULATIONS. 45% OF THE LAWNS ARE FERTILIZED WITH 2.4 l~ N/lOOO
SQ, FT" AND THE REMAINING 55% ARE UNFERTILIZED.
~...p.----
17
Table m-z Assumptions related to nitrogen inputs for W ALRAS simulations of
residential development
Turf
. 45% fertilized with 1.Z lb N/1000 sq. ft. on May 13 and another 1.Z lb
N/1000 sq. ft. on September 10.
. 55% receiving no fertilizer.
. Lawn fertilizer divided into half fast-release form and half slow-
release organic form for uptake later in the growing season.
. Turf mowed every 1Z days during the summer, with removal of 50
percent of the clippings.
Roeei<:lomtial
Land Cover FractionsZ
% Other % Impervious
Houses/ Acre People/House 1 % Turf Vegetation3
0.5 Z.54 18 61 Zl
1.0 Z.54 Z5 50 Z5
1.4 Z.54 3Z 39 Z9
Z.O Z.54 38 Z8 34
Z.9 Z.54 45 17 38
4.0 Z.54 40 14 46
1) From: 1980 Census for the Town of Southold.
Z) From air photo analysis, unpublished data.
3) Vegetation other than turf is assumed to be unfertilized. In cases where
gardens or other plantings receive fertilizer, our simulation results may
underestimate nitrate leaching concentrations.
18
to
.
.
.IS!!.
7
{ L.wn. f.rtlllud with
. 3 lb. N/1000 sq. ft.
Nltrlt. I fS'" of I.wn. ,...Ived
l.achld . 24 Ib. NII000 sq. ft.
Ime/II 55.. .re unf.rtlllz.d
. ISuney r..ults for
I Southold )
. {No 'I... fertlllutlon
2
1
. FIGURE 1II-3. SIMULATED NITRATE LEACHING
CONCENTRATIONS FROM A RANGE
1 2 . . OF HOUSING DENSITIES AND LAWN
Numb.r of Hou.../Acr' FERTILIZATION RATES.
Table m-3
Comparison of Southold housing densities with the percentage of
time that the 10 mg/l nitrate standard can be expected to be
exceeded.
With ~5% of
Lawns
Receiving With All
2.4 lb N/I000 Lawns
Housing With No sq. ft. Receiving
Density Lawn and 55% 3 Ib N/I000
(houses/ acre) Fertilization Recei vinJ;c None sq. ft.
0.5 0-1% 0-1% 1-10%
1.0 0-1% 1-10% 1-10%
1.4* 1-10% 1-10% 10-50%
2.0 1-10% .1-10% 10-50%
2.9* 1-10% 10-50% 10-50%
4.0 10-50% 10-50% 10-50%
* These densities are included because they represent the net housing densities
created by clustering 2-acre or I-acre zoning into 35% of the land area.
Cluster 9lIo Sprawl Development
A subarea of the Town of Southold
was chosen for simulation of the effects
of clustered housing development on
nitrate concentrations in ground-water
recharge. Bounded by Reeves Avenue,
Middle Road, Henry's Lane, and the Long
Island Sound, this subarea is portrayed in
Figure m-4. Currently this region is
zoned at one house per two acres, but
Southold allows clustering into 50% of the
land area, so a net housing density of one
house per acre is allowed in the
developed portion. Usually in a cluster
development the remaining land would be
left as open space covered by
unmaintained vegetation such as
woodlands or meadows rather than lawns
or crops. This provides recreational space
as well as a buffer area to help
compensate for the increased impact to
ground water of spacing the houses more
closely together. In Southold, one of the
reasons for considering denser spacing of
houses is to make it .possible to preserve
valuable agricultural land in inland areas
by clustering houses along the shoreline.
This does not fit the traditional concept
19
of clustered development, however, since
the open space would be in another
intensive use rather than left as vacant
land.
Figure m-5 shows the results from
simulations representing clustered housing
development at densities of either one or
two houses per acre. When the remaining
half of the land area is left in unfertilized
vegetation, the nitrate leaching
concentrations remain lo.w (Figure m-5 a
and b). If this land is used for agriculture
instead, however, the concentrations
increase two or three-fold to levels
exceeding the 90% compliance level of 6
mg/l (Figure m-5 c and d).
Southold is considering changing its
cluster ordinance to provide more open
space by allowing closer spacing of
houses, using 35% rather than 50% of the
total land area. As shown in Figure m-6,
the nitrate leaching levels become higher
still if 35% of the land area is used for
clustered housing and the remaining 65%
for agriculture.
..0
00
..0
,0.
...0.,.6
..<
o.'c
,.0
FIGURE 111-4; SUSAREA OF THE TOWN OF SOUTHOLD, LONG ISLAND, N.Y.
20
Nltr.te LeaChing 2.4 mg 11
~
Nltrat. Leeching 3.5 mg/l
~
Nitrat. l..Ching 7.1 mg/ i
Nltr.t. La8Chlng 7.8 mg/l
o 1 2 S .. 5 . 7 . mall
FIGURE 111-5. THE EFFECT OF CLUSTERED DEVELOPMENT ON THE NITRATE CONCENTRATION
OF RECHARGE WATER. HOUSES ARE CLUSTERED INTO 50% OF THE LAND
AREA, WITH EITHER AGRICULTURE OR UNFERTILIZED VEGETATION ON THE
REMAINING ACREAGE.
Filling the open space with
agriculture is contrary to the usual
definition of cluster development. The
basic concept behind clustering is that
'land is left in open space to compensate
for the increased housing density. In
Southold, where nitrate and pesticide
contamination of ground water are
problems, if housing is allowed to be
clustered then the remaining open space
should be reserved for unfertilized
vegetation or other uses which would
provide the highest quality recharge
water. The high fertilizer and pesticide
requirements of land uses such as golf
courses or some types of agriculture make
them intensive uses in
-
..
E
-
-
~
-
-
.. > .. > .. > .. >
.. .. .. .. .. .. .. ..
:il :il :I .. :il 0 .. ..
.. .. .. ..
% % % % % % % %
.. .. .. .. .. .. .. ..
0 o .. .. 0 :il tll tll
'-- .. .. .. .. .. ~
-
.
.
"
.
"
u
.
~ .
c
.
..
g
z
2
o
. .
Clustered
2-.or.
zoning
c .
Clust....d
'-80r.
zoning
p.. potato fields
H- housing
Y.. vacant 'and
(a,) Net Housing Density. 1.0 hoUlflI ecre
lbl Net Housing D.nalty.1.4hou...l....
(eJ Net Housing DeMlty. 2.0h~/ac,..
(dl Net Housing Den.lty. 2~Slhou"'/.cre
FIGURE 111-6. THE EFFECT OF VARIOUS
CLUSTERING OPTIONS ON
N>lTRATIl CONCENTRATIONS
LEACHING TO GROUND WATER
FGR A SUIlAREA OF SOUTHOl.D
N.Y.
terms of ground-water quality, so they
should be associated with low density
housing rather than high density clustered
developments. Recommendations for
converting land from other uses back to
natural, unfertilized vegetation can be
obtained from Cooperative Extension, the
Soil Conservation Service, and the
Nonpoint Source Handbook in preparation
by the Long Island Regional Planning
Board (LIRPB, 1983).
Using W ALRAS estimates of the
amounts of water and nitrogen recharged
from potato farms, unfertilized areas, and
21
residential developments of various
densities, it is possible to calculate what
combinations of these land uses would
provide recharge that would meet
whatever nitrate standard is set. The
problem with this approach, however, is
that it would provide only an average
nitrate concentration for the entire study
area shown in Figure m-4, encompassing
nearly 1500 acres and a variety of land
uses. The homeowner whose well
consistently exceeds the drinking water
standard for nitrate will not be consoled
by the fact that his neighbor's well is
consistently low, providing an acceptable
average for the area as a whole.
A more rational approach to
planning for ground-water quality is to
decide that each individual land use must
meet certain quality standards. Since
ground-water flow is made up of water
trickling slowly through small
underground pores, it does not involve'
much mixing as in surface water rivers
and streams. As shown in Figure m-7, the
effects of different land uses remain
distinct within the ground water, so the
quality of water obtained at any given
weU depends on its placement and depth
in relation to these ground-water flow
paths. The recharge concentrations from
various land uses should therefore not be
averaged as if the recharge water from
these sources were mixing in a vast
underground reservoir. Instead, each land
use should be analyzed individually to see
whether quality standards can be met.
Housing densities can be analyzed in
this manner using calculations such as
those represented in Figure m-2. The
potato farming results in this chapter are
based on an average fertilization rate of
175 lb Nt Ac at planting. The effects of
varying this rate and timing are discussed
in the following chapter, and the nitrate
concentrations produced by other land
uses, such as orchards, vineyards, or horse
pastures, are presented in Chapter V of
this report.
22
FISURE 111-7. EFFECT OF LAND USES ON GROUND-~ATER QUALITY.
I . . . I .;.....~:< :.:'.::~.'~!.' ~.'., :.::..:....::.< ~ '... ..
t,;;:,;~t~D~.?;,:-l~.i~:l,:'7~L.~:;~';,'~!~) . '. ". . '. .... "
~:~'?~;~;~-;:-~i/~.~\J;';;:" ~t;:~;;;;~~:-'~ ?~. ~..~.!.;.:.~.:.~.'.~.~_...'..[.~::...r.,._s.:,:.:~_..~:~:'.:...i....:_f.::_._~~;.{.._..:.:.~.~_....~T.~...~f.~:_.i.._..~...E.~...~....._.:._.:. ...:.:_......~.~::.'_;.:_~:::..::..._~.:.:.:.~.~......._:........;...~.'..._~..:.'.::~.:..'::..',_..f..,..~.:....:._..i.:...~.....,._...:~.....:..~.~....~..'.:.... ".; . , .. . '
I . . \. '. --.__ _ _ _ :_..:-..~~:-._~..._.:.:~...:.,...::l:..~.....:.:-...:,...:.~.......:~......~....:-.;~.:..~:.,_..
\,n):;;5w~,'x:':{ '.' .... ""..,'. ..... "'> :>
~~~ ':: ~ ~~'.~ ~: :':<. '~'.-~-;.: ..:~ .~~~~. .Influence of potato field 'o~ saturated zone.. . .~' : ..~.~.;i:.;.:~.~.~.~.:
;;{-'"j}~,<;i~12~!,str~::~~~:':~~~_k~<>'--
.' :... .," . . '.. . '.' -' ~. :. ;.. r.: .".. "'._ ..." ".
Potato Field
,.'. '."
"
..,....
Residential developments can
contaminante ground water with
che.micals other than nitrate. Use of
nitrate results should therefore be only an
initial step in planning land uses that are
compatible with ground-water quality.
Consideration also needs to be given to
providing protection against
contamination by synthetic organic
chemicals contained in household,
commercial, and industrial products.
Potential ContamiDation by Oqramc
Chemicals
Organic chemicals contained in
certain household products have been
observed in ground water underlying
residential areas on Long Island. These
chemicals enter ground water through
the on-site domestic wastewater disposal
systems, leaks from underground storage
tanks, and spills on the land surface.
In order to assess the impact of
these chemicals from residential areas on
ground water, the four Long Island
communities of Mastic, Mastic Beach,
Wading River and Rocky Point where
organic contamination has been observed
were selected for study. (Figure m-8).
These communities were selected because
on-site domestic wastewater disposal
systems are used throughout each, and
because there is little or no industry so
the organic contamination in each must
be due to the residential and commercial
activities. Most residents of these
communities rely on private house wells
for their water supply. Much of the water
drawn from wells in each community is
water that has been recharged from land
in the same community, although to some
degree, water recharged outside of each
community also is used. Rocky Point and
Wading River are located on the north
shore and do not extend very far inland.
Hence some of the deeper wells in these
communities are probably withdrawing
water which originated as recharge
further inland. Mastic and Mastic Beach
are adjoining commimities - Mastic Beach
is located on the south shore and Mastic is
located inland of Mastic Beach. Most of
the wells in Mastic probably draw water
which was recharged there, and wells in
Mastic Beach obtain water which was
recharged in either Mastic or Mastic
Beach.
The Suffolk County Department of
Health Services began testing water from
individual home wells for these chemicals
in the late 1970's and since 1981 has
tested for the presence of 15 organic
contaminants (Benzene, toulene, m-
xylene, p-xylene, o-xylene, chloroform,
bromoform, bromodichloromethane,
chlorodibromomethane, carbon
tetrachloride, methylene chloride,
trichloroethylene, tetrachloroethylene,
trich1orotrifluoroethane, 1,1,1-
trichloroethane). In 1981 and 1982 the
LONG ISLAND SOUND
(,;
.
.~) N....u f Su'folk
J L J
... Dng I Island
~
23
County Health Department collected and
tested approximately 1000 water samples
from these four communities for organics.
The assessment used in this study is based
on the 1981 to 1982 data set.
The ten chemicals listed on Table
m-4 were detected in one or more water
samples from these communities. All of
these chemicals can produce immediate
adverse effects in humans if ingested in
large doses (National Research Council,
1977). These chemicals may also be
carcinogenic in small doses. The doses
which a person would receive from
drinking ground water contaminated to
the levels found during the Health
Department's sampling program would not
induce accute toxic effects but might
cause cancer (National Research Council,
1977).
Table m-5 shows the number of
wells where each chemical was found.
Twenty-four percent of the well water
N
I
ATLANTIC OC....N
FIGURE 111-8. FOUR LONG ISLAMD COMMUNITIES TESTED FOR CONTAMINATION
OF GROUND WATER BY ORGANIC CHEMICALS.
Table m-4
Description of Organic Chemicals Found in Ground Water Underlying Residential Communities
on Long Island, New York
Contaminant
Possible
Sources
Guideline for Maximum
Concentration in DrinltiQlZ Water
KnoWD or
Suapected Adverse
Health Effect..
. Benzene
Gasoline, Other Petroleum
Producu
Paint Remoyer
SolyeDt. and Cleaning Fluids
5ug/l..
Obsened to cause cancel' (leukemia)
Toxic at high dose.
. Toulene
Gasoline. Other Petroleum
Product.
Paint Remoyer
Driveway Degreaser
Salyent. and Cleaning Fluids
Engine Degrebel'S
SO ug/l
Narcotic effects at high doses
Insufficient data on kmg term
effect.
. Chloroform
. Trichloroethylene
Sohrent. and Cleaning Fluids
Dry Cleaning Fluids
50 ug/l Suspected of causing cancer
Toxic at bigb dose.
SO ug/I Suspected of causing cancer
Toxic at high dose.
SO ug/I Toxic at high dose. '"
Insufficient data on long term ..
effects
50 ug/ I Insufficient data on long term
effects
SO ug/ I Suspected of causing cancel'
Toxic at high doses
50 ug/l Toxic at higb dose.
May cause birth defects
. Tetrachloroethylene
Solyent
.I,I,I-Trichloroethane
Cesspool Cleaner.
Oven Cleaner
Solvent. and Cleaning Fluids
. Carbon Tetrachloride
Solvents and Cleaning Agents
. Xylene
Guolble
Garage DegreaseI'.
Cleazaing Fluids
Lacquer Thinner
Tar Remover
. Chlorodibromomethane
Unknown
SO ug/I
Insufficient data on long term
effects
. Methylene Chloride
Paint RemMel'
Cesspool Cleaners
Oven Cleaners
Cleaning Fluids
Engine Degreasel'S
50 ug/l
Insufficient data on 10Dg term
effect.
.
Source: National Research Council, 1911.
..
Micrograms per liter (ug/l) is the same as parts per billion.
25
Table m-5
Number of Wells Affected by Organic Chemical Contamination in Wading River,
Rocky Point, Mastic and Mastic Beach
Number (and Percent) Number of Wells Highest
of Wells Where Detected Concentration
Contaminant Where Detected Above Guideline Found
Benzene 4 (.4%) 4 (.4%) 170 ug/l
Toulene 5 (.5%) 2 (.2%) 62 ug/l
Chloroform 14 (1.4%) 0 29 ug/l
Trichloroethylene 17 (1.7%) 1 (0.1%) 11 0 ug/l
Tetrachloroethylene 51 (5.1%) 4 (0.4%) 1100 ug/l
1,1, I-Trichloroethane 203 (20.3%) 23 (2.3%) 330 ug/l
Carbon Tetrachloride 2 (0.2%) 0 7 ug/l
a-Xylene 1 (0.1%) 0 8 ug/l
Chlorodibromomethane 1 (0.1%) 0 2 ug/l
Methylene Chloride 1 (0.1%) 1 (0.1%) 80 ug/l
samples contained detectable amounts of
at least one organic chemical and 3.7%
contained one or more chemical at
concentrations greater than the State
Department of Health guideline for the
maximum concentration allowable in
drinking water. The chemical found most
often was 1,1,1 trichloroethane, a major
ingredient in cesspool cleaners. Xylene,
chlorodibromomethane, and methylene
chloride were each found in one sample.
Benzene, a known carcinogen and the
contaminant with the strictest guideline,
was found in 0.4% of the samples.
The data set presented here is not
large enough to make any general
conclusions about the percentage of wells
contaminated in excess of the ~ideline.
It should be noted that drinking water
wells usually give biased samples and are
not a good guide to assessing overall
ground-water conditions. Mastic Beach
has a higher percentage of wells with
contamination in excess of the guideline
than the other communities, and this may
be related to several factors including the
high density and the fact that there is no
non-residential area adjoining Mastic
Beach from which uncontaminated water
could come.
The four communities studied are of
different average housing densities.
Figure m-9 graphs housing density versus
both the percentage of wells tested where
organics were found and the percentage
of wells tested where organics were found
at co~centrations greater than the
guideline for drinking water. Table m-6
28
.-Organics Detected
i-Organic. Detected
Above GuicMIin..
. 40%
u
.c
. Rocky .
!!'
0 Point
! 30"
. M..tlc: ·
~ ..
it . -...
.. 1;
. .
... ~
e 20"
.
Ul ! Mastic.
.!! ~
..
it.
0 10"
C Wodl.. . ~
. R'_
u
~ , .
..
1 2 3 .
Average Housing o."lity: 1977 & 1982
(dwelling unlt,/acre)
FIGURE III -9. Hous ING DENSITY COMPARED WITH ORGANIC CHEMICAL
CoN'l'AM'l NAT I ON OF GROUND WATER IN FOUR LONG ISLAND
CllMMUN-ITIES.
Table m-6
ComllmlOD of AYerqe Houaing Density With Organic Chemical and Nitrogen Contamination
of Gl'OUDd Water in Four Long Island Communities
Percentage of
Wella Sampled
Percentage of Where Organics Average
land DUmber) Were Detected Nitrogen
Average Number of of Wells at ConCeit- Number of (Nitrate plus
Housing Density Wella Sampled Sampled centratiou in Wells Sampled Ammonia)
1977-198Z fol' Organics Where Orpaia Excess of the for Nitrogen Concentration
Community (Houses/acrel 1981-1982- Were Detected GuideHne 1981-198Z mllll
Wading 1.0 67 8% (5) 0%(0) no 3.1
Rtyer
Mastic Z.O 317 18% (57) Z% (6) 316 3.8
Mastic Z.7 508 29% (147) 6% (31) 50Z 3.8
Beach
Rocky 3.9 97 36% (35) 1%(1) 109 4.4
Point
presents the data on which the graphs
were based. From the graph it appears
that the percentage of wells affected in a
community is directly proportional to the
housing density. . This observation
supports the theory that each house with
its own on-site sewage disposal system is
a potential source of organic
contamination.
Table m-6 also shows the average
nitrogen concentration measured in each
community over the same period. As is
27
expected the average nitrate level
increases with housing density. However
the presence and concentrations of
organic chemicals in individual samples
are not correlated with nitrate
concentrations in the samples. Many of
the water samples contained high
concentrations of organics and a low
concentration of nitrate. It is stressed,
however, that drinking water wells are not
located according to a pattem which
would best measure the impact of sources
of nitrogen. In fact, the intent of locating
drinking water wells is to avoid
contamination.
28
29
Chapter IV
EFFECTS OF POTATO FARMING ON GROUND-WATER QUALITY
The well drained soils in Southold
have required fertilization ever since the
native Indians used fish to provide
nutrients to their crops of corn, beans,
pumpkins, and squash. Early English
settlers had little manure or other
fertilizers available and frequently had to
abandon pastures when the soil lost its
natural fertility. Introduction in the early
1800's of commercial fishing as a source
of fertilizer produced dramatic increases
in crop yields and started the trend of
regular fertilization of Lonli Island crops.
Other fertilizer sources included guano
from Peru, wood ashes delivered by a
sloop, and horse manure brought by rail
from New York City. Commercial
fertilizer became available in 1844, and
formulation of fertilizers to meet Long
Island conditions began in 1921. Invention
of the mechanical potato digger in the
1880's provided an important boost to
potato farming, and by the 1900's growth
of potatoes had become a major crop on
Long Island.
Potato FertiBsatioa Rates
A 1929 survey of Long Island potato
farms showed the average fertilization
rate to be 100 lb N/ A (pounds of nitrogen
per acre), with over half the farmers also
applying 7.7 tons of manure (Underwood,
1933). By 1975, potato fertilization rates
had vastly increased, with most farmers
applying from 200 to 250 lb N/ A (Chu and
Selleck, 1977). Other nitrogen sources,
including other agricultural crops,
residential septic systems, and lawn
fertilization, also had increased, and
nitrate pollution had been identified as a
major problem in Long Island ground
water. Since then much research has
been carried out with the aim of making
potato fertilization rates compatible with
ground-water quality. As a consequence,
Cornell recommendations for fertilization
of Long Island potato fields dropped from
a range of 175 to 240 lb N/A before 1975
to a range of 125 to 175 lb N/A from that
date on. Typical current practice for
Southold potato farming is to apply an
average of 175 lb N/A a~ the time of
planting in April or May, with individual
farms ranging from 150 to slightly over
200 lb N/ A.
In order to analyze the effects of
potato fertilization on ground-water
quality, we used the Water and Land
Resource Analysis System (W ALRAS) to
simulate five potato fertilization rates
under climate and soil conditions typical
of 'Southold. These five rates were
designed to represent a range
encompassing average current practice as
well as the extreme low and high ends of
the scale, ranging from 100 to 300 lb N/A
applied at planting.
Two different soil tjpes were used
in these simulations. The first, Riverhead
and Haven sandy loams, represents a
group of soils which are prime for
agriculture and which are found on most
of Southold's farms. The second, Carver
and Plymouth .sands, represents a group of
soils which are much less fertile and are
often used for farming when they form
portions of a field with a better soil type.
These soils also are much more highly
permeable than the Riverhead and Haven
sandy loams and therefore much more
susceptible to leaching of fertilizer
nitrogen.
As expected, our simulations show
less nitrogen leaching when less fertilizer
is applied (Figure IV-I). On the Riverhead
and Haven soils, the current average
30
30
o - Carver 8nd Plymouth Sanda
. - Alverhe.t and H.qn SIIpcSy Lo.m
-
:::
..
E
i
X
o
..
.
o
~
i 10
o
100
150 175 200
F.tlllur Applied lIb N/A/Yr!
300
FIGURE IV-I. THE EFFECTS OF POTATO FERTILIZATION RATES ON
NITRATE CONCENTRATIONS LEACHING TO GROUND WATER
FOR TWO SOIL TYPES IN SDUTHOLD, N,y,
0) AVERAGE PRACTICE IN SOUTHOLD IS 175 LB N/A/YR ON
RIVER HEAD AND HAVEN SANDY LOAMS
fertilization rate of 175 Ib N/A produces
leaching concentrations around 8 mg/l,
witb a range of 6 to 11 mg/l as
fertilization is increased .from 150 to ZOO
Ib NI A. The concentration leached can be
decreased to 4 mg/l if only 100 Ib N/A are
applied, but this fertilization rate is too
low for satisfactory potato yields. The
300 Ib NI A rate contaminates recharge
witb over ZO mg/l' nitrate and obviously
supplies far more nitrogen tban the plants
can use. On the Carver and Plymouth
sands, leaching rates are dramatically
higher and drop to 10 mg/l only at the
unacceptably low 100 lb N/A fertilization
rate. Since these sandy soils do not
produce a good potato crop, they are
used only when they form. portions of
fields with a more fertile soil type.
After an extensive study of nitrogen
needs for optimal potato growtb
. consistent witb ground-water quality on
Long Island, Meisinger (1976)
recommended that Suffolk County
growers reduce their fertilization rate to
about 150 lb N/A. This was based on
research on Katahdin potatoes, and the
fertilizer needs of other varieties are
slightly different. Rykbost et al. (1977)
concluded, however, that the yields of
Katahdin, Cascade, Superior and Hudson
potatoes in Suffolk County were not
significantly increased by raising
fertilizer applications over 150 lb N/A.
Figure IV-Z represents a compilation
of over twenty years of research at the
Long Island Horticultural Research
Laboratory on fertilization of Katahdin
potatoes, one of the most common
varieties grown in Southold. Nitrogen was
supplied in a variety of forms including
urea, ammonium nitrate, ammonium
sulfate,. and mixed fertilizers, with both
single and split applications. As can be
seen in Figure IV-Z, the optimal
fertilization rate under this range of
..
~
.
~
t
;:
co
-
..
1
...
2ft'
1)- _- 1SIl
- ,.
31
conditions was found to be around 150 lb
N/A. Since potato yields do not increase
beyond this point, the additional dollars
spent on fertilizer detract from net
profits for those fields. The optimal
fertilization rate might be different for
other potato varieties.
Split AppJicatious
Kossack and Selleck (1979) and
other researchers have recommended that
potato fertilization on Long Island be split
so that a portion is applied at planting and
the remainder in five or six weeks when
the plants are growing rapidly and have a
better chance of taking up the nitrogen
before it is leached (Figure IV-3). Field
research has verified that split fertilizer
applications produce comparable potato
yields to single applications, with reduced
losses of nitrogen to the ground water
(e.g. Rykbost et al. 1979).
1SIl- 175- _ - 2$1)-
m__3IlCil
,..t_ __ II~ M/IiIV,I
FIGURE IV-2. RESULTS OF FIELD EXPERIMENTS CARRIED OUT FROM 1956
TO 1978 AT THE L.I.H.R.L. ON YIELDS OF .~ATAHDIN,
POTATOES AT VARIOUS FERTILIZATION RATES.
32
FIGURE IV-a. COMPARISON OF N,ITRATE LEACHING FROM HEAVY FERTILIZATION AT
PLAN:r.ING va LIGIt'l"ER feRTILIZATION WITH SPLIT APPLICATION
PRICIPITATION
~~
\~,
~'\~
----------- ----- ----- -_._- --------------------
PRICIPlTATION
~~
Research on five common potato
varieties at the Long Island Horticultural
Research Laboratory (Baier, J.H., and
K.A. Rykbost, 1976) has shown that an
application of 50 Ib N/ A at planting is
adequate to carry the potato crop through
the four to six inch plant height stage and
that additional nitrogen needs to be
applied prior to the period of most rapid
upta~e, approximately five to seven
weeks after planting.
Using WALRAS, we simulated four
different schemes for applying 150 Ib N/ A
on Southold potatoes:
a) 150 Ib N/A at planting
b) 100 Ib N/ A at planting, and
50 Ib N/ A 5 weeks later
c) 50 Ib N/ A at planting, and
100 Ib N/A 5 weeks later
33
d) 50 Ib 'N/ A at planting, 50 Ib
N/ A 5 weeks later, and 50 Ib
N/ A 8 weeks after planting.
The simulated split application
schemes show substantial improvement
over a single application in terms of both
lowered leaching concentrations and
increased tuber nitrogen contents (Figures
IV-4 and IV-5). This is especially true for
potatoes grown on Carver and Plymouth
sands, where the highly permeable soil
looses nitrogen rapidly unless the plants
can assimilate it before it has a chance to
leach.
Timing of the nitrogen availability
is critical for proper tuber development.
Applying the fertilizer too late can
stimulate top growth but retard tuber
formation and development. Field studies
at the Long Island Horticultural Research
Laboratory have shown that the highest
0- Can... and Plymouth Sand.
11- RI~r"ad and Haven S.ndy LotIrn
15
,
;'10
..
.
..
u
.
.
...
z 5
o
Fertilizer APPlied lib HIA tVr J
FIGURE IV-4. EFFECTS OF SPLIT APPLICATION OF FERTILIZER ON
SIMULATED NITRATE CONCENTRATIONS LEACHING TO GROUND
WATER FROM POTATO FIELDS IN SOUTHOLD, N.Y.
.THESE REPRESENT SPLIT APPLICATIONS AS DESCRIBED IN THE TEXT.
140
t: 120
..
,
Z
,e
; 1Q
"
~
..
Z
80
80
50'
50
50
5lh
100
Fertilizer Appll~ lib N/A /Yr I
34
Rlverhe.d and Haven S.ndy Lam -II
C.rvar and Plymouth Sands - 0
100-
50
150
FIGURE IV-5. EFFECTS OF SPLIT APPLICATIONS OF FERTILIZER ON
SIMULATED TUBER NITROGEN CONTENT IN SOUTHOUD, N.Y.
'THESE REPRESENT SPLIT APPLICATIONS AS DESCRIBED IN THE TEXT.
nitrogen use efficiency for potatoes can
,~ --
be obtained by applying a portion of,
fertilizer at planting and the remainder
from plant emergence to the six to eight
inch stage.
Effec:tll of Heavy SpriDg Raiaa
It is not uncommon in Southold for
heavy rains to occur in the Spring, leaving
potato growers wondering whether
additional fertilizer applications are
needed. In order to respond to this
question, we simulated potato growth for
typical years with average and above
average precipitation amounts, adding an
extra 13 inches of rain in June. This
extra June rainfall is similar to what
happened in Southold in 1982 but is more
extreme than Southold's usual spring
weather. Fertilization was set at 175 lb
N/ A at planting, an average figure for
Southold.
As shown in Figure IV-6, in an
average year on Riverhead and Haven
soils, approximately 20 percent of the
fertilizer nitrogen is lost to the ground
water. The additional 13 inches of rain in
June increases leaching losses to close to
30 percent of fertilizer nitrogen. In a
typical wet year, fertilizer loss is 40
percent, and this increases to 48 percent
with the additional June rain.
In order to respond to the question
of whether additional fertilizer is needed
after a heavy spring rainfall, examination
needs to be made of the effects on potato
yields of the additional losses of fertilizer
nitrogen, Table IV-I shows the simulated
tuber nitrogen and leaching losses per
acre averaged over three years of
weather, with and without the extra June
rain. The extra June rainfall makes a
relatively small difference in the amount
of nitrogen leached and the amount
accumulated in the tubers. In all cases
the reduction in tuber nitrogen is less
than ten percent, with the highest loss
occurring with the three-way split
application because of the close proximity
between fertilizer application and the
heavy rain. Even with the extra rainfall,
however, the split application schemes
still are the best at'keeping nitrogen in the
root zone where it is available for uptake
by plants.
Eccmomic CoIIIIequeDces of Varioas
Fertilisation
Practices
The economic consequences of
various fertilization practices depend on
the current prices of .fertilizer, which are
known at the beginning of the growing
season, and on the market price for
35
potatoes that prevails after harvest.
Growers must therefore make fertilizer
decisions without knowing in advance
what the economic consequences will be.
In a study of four Suffolk County
farms, Rykbost et al. (1977) compared
usual grower practices with fertilization
rates recommended by the Long Island
Horticultural Research Laboratory.
.Fertilizer applications by the growers in
the range of 185 to Z70 Ib N/ A yielded
one to five percent more of the largest
category tuber (greater than 1 7/8 inches)
than did fertilization in the lower
recommended range of 133 to 154 Ib N/A.
Although these yield differences are too
small to be statistically significant, they
are useful as an example for comparing
net profits.
Ie'
FIGURE IV-5. EFFECTS OF HEAVY SPRING RAIN ON NITROGEN LOST FROM
POTATO FIELDS GROWN ON RIVERHEAD AND HAVEN SOILS.
SHADED AREAS SHOW ADDITIONAL FERTILIZER LOSS DUE TO
THE EXTRA 13 INCHES OF RAINFALL IN JUNE.
1
II:
1
.
Ie
I
...
z
'"'V._AIiI
40
~
::::
.%
'l5
~
.
...
28
o
,.lilt..
~
Moly 1
.-1
,
_31__1
_1___1
July 1
11 ......
_ra r....
Aul1
s.,.t 1
..
p...:klBII
tt.r1J Ill"
38
Table IV-I. Simulated values for nitrogen leached and nitrogen content of
potatoes grown on Riverhead and Haven soils. Results represent
the average of three years of weathe~, with and without addition
of extra spring rainfall.
Nitrogen Leached Nitrogen in Tubers
(lb N/ A) (lb N/A)
Fertilizer Without With an Extra Without With an Extra
Application Extra June 13 Inches of Extra June 13 Inches of
(lb N/A) Rain Rain in June Rain Rain in June
300 165 169 138 138
2.00 78 83 130 12.9
175 61 68 12.5 12.0
150 49 53 114 112.
100-50 * 42. 49 12.1 116
50-100* 38 45 12.5 12.1
50-50-50* 35 43 12.8 12.1
*These represent split fertilizer applications, with a portion applied at planting
and the remainder applied from 5 to 8 weeks later.
Whether the additional yield of
large potatoes is worth the extra
fertilizer cost depends on the current
market price for potatoes. It is evident in
Table IV-2. that for 1976 fertilizer prices
the grower at two of the four sites would
have come out ahead by using less
fertilizer, even at the highest tuber price
analyzed ($4.00/cwt). At the middle and
low tuber prices ($3.50 and $3.00/cwt),
three out of the four growers would have
had higher economic returns by spending
less on fertilizer. Fertilizer and other
prices have risen since 1976, and this past
year Southold farmers lost money
regardless of their fertilization rate
because the $3.50/cwt price for potatoes
was too low to meet their costs.
In general, higher fertilization rates
become economically more advantageous
as tuber prices rise. Since market prices
are not known until the end of the
growing season
dramatically from
however, growers
decisions without
knowledge.
and can fluctuate
one year to the next,
must make fertilizer
the benefit of this
The favorable yi~lds shown at 150 to
175 Ib N/ A and the hazards to ground
water at higher fertilization rates make
this seem to be a good average to aim for
for potato fertilization in Southold. Split
application can further reduce the
leaching losses, keeping nitrogen in the
root zone where the plants can use it.
Potato Pest MaDageDIeDt
In considering pest management as
. it relates to ground-water quality on the
North Fork, there are several key factors
that have to be taken into account. These
include: the extent of farming in the
area, the intensity of crop production, the
production of potatoes as a monoculture,
and the nature of the sandy soils upon
which the crops are grown.
On the North Fork it would be
difficult to overstate the importance of
farming to the local economy. The
fraction of Southold's land devoted to
farming and the value of the crops
produced, have always been high. For
example, out of a total area in Southold
of 35,600 acres, 30,400 acres were
farmlands in the early 1900's (Bond, 1947).
By 1940, the farmed acreage had
decreased to just over 15,000, a fraction
which was still close to 50% of the total.
During the intervening years, the area
farmed has slowly further decreased as
the population of Southold has increased.
Nevertheless, nearly 40% of the total land
remains in farming.
Since the 1930's, potato farming has
accounted for about half the cropland as
can be seen from Figure rv-7. For
decades, the practice has been to grow
potatoes continuously with little rotation.
37
This pattern of production takes
advantage of the long mild growing season
and the fertile soils found on the North
Fork. The specialization of farmers in
potato growing has developed a high level
of proficiency, reflected in the high yields
of Long Island potato farms. As shown in
Table rv-3, the yields of potatoes on Long
Island are consistently greater than the
national average. Potatoes are grown on
Long Island generally as a late summer or
fall crop. Compared to similar areas
elsewhere in the United States which
grow late potatoes, the average yield on
Long Island was 257 cwt/acre compared
to 222 cwt/acre for all late potatoes over
the twenty-five year period from 1955.
Both yields can be compared to the
overall average yield for all potatoes
grown in the United States of 215
cwt/acre. During the 25 year period,
Long Island was only below the average
for the United States for six years.
Considering the vagaries of the weather
and pests, this is a remarkable
achievement.
Table rv-Z. Economic consideration of potato fertlli'z;ation rates. (Taken from RybOlt ot al., 1979)
-- --- - - - - - - ----------.--- - ----------- - - ---
$3.00/cwt $3.50/cwt $4.00/cwt
Fertilizer Tuber Tuber Tuber
Applied Fertilizer. Income, Balance, Income, Balance, Income,
Site (lbN/Acl Cost. $/A ~ $/A ~ $/A ~ Balance
Southold ZI7 16Z 836 67. 97' 81Z 1,114 95Z
154 !Z5 804 679 938 813 I,On 9.7
-5 -1 +5
Water Mill 185 156 1,094 938 1,1.76 1,1Z0 1,458 1,30Z.
,.5 119 1,078 959 I,Z58 1,139 1.437 1,318
-ZI -19 -16
Wa.iDscott Z70 177 716 539 835 658 95. 777
"9 lZ0 698 578 81. 69' 930 810
-'0 -36 -33
Orient Point ZOO 16Z 987 815 1,151 989 1,316 1,154
133 lI8 937 819 1,093 975 1,1.50 1,13Z.
+6 +1' +ll
- - -- ----- ---- - - - -- - - - --- -.-- - - - ---------
. Bued on Jumbo and A tube" sampled [rom 6 X IS-foot row.
f FertiliZe\" cost (provided by Aiway at Long bland on 11/11176 on bulk price). 8-16-8 S137.Z,5/ton, IO-lO-tO SI66.50/ton, 3-
18-9 SUO.OO/ton, N~N03 SI53.00/ton, Urea SI70.00/ton.
Ul
W
o
...
c
...
o
ll.
Q
Z
C
Q
Z
C
...
:a
II:
C
...
Z
Ul
w
II:
tl
C
20,000
15.000
]Jl!l!:'-
, ,
, , . " ...,
".flr!l\._b....n....... "
,
1(),()00
,,~!.!I:tO.
..... ....~.
",
s,000
". /."
1'1""
1'" 1'1.
'l'1M'"
38
2000'
1800
1800
Ul
Z
o
Ul
II:
W
ll.
...
o
1400
".
II:
W
III
:a
::l
Z
1200
1...
11.
FIGURE IV-7, CHANGES IN POPULATION AND ACREAGES OF FARM LAND AND
LAND USED FROM POTATO PRODUCTION IN THE TOWN OF
SOUTHOLD, N.Y. FROM 1930 TO 1980.
Five of these six low years occurred
in the first half of the 1970's, a period
during which potato pests on Long Island
had become particularly difficult to
control. The monoculture potato farming
on Long Island has fostered vigorous
populations of various pests including the
Colorado potato beetle, aphids,
nematodes, weeds, and the potato late
blight. The most voracious and
potentially damaging of these is the
Colorado potato beetle.
Infestations of the beetle were
especially damaging in the 1970's until the
introduction of the pesticide aldicarb in
1975. In the five years up to 1976, Long
Island potato growers achieved an. average
yield of 226 cwt/acre. During the next
four years when aldicarb was used the
average was very nearly 300 cwts/acre.
Aldicarb was withdrawn from use on
Long Island when its presence in ground
water was confirmed in 1979. Another
pesticide used against the Colorado
potato beetle, carbofuran, also was
withdrawn following the widespread
detection of the pesticide in ground
water.
The fate of pesticides in the soil
depends on their chemistry and the soil
properties. Principal factors which
determine the characteristics of the soil
ecosystem are pH, soil water, organic
matter and soil physical characteristics.
On Long Island generally, and on the
North Fork in particular, the soils have a
low pH and the amount of drainage is
high, with an average recharge of over 20
inches per year. The soil organic matter
is low, and the soils are sandy with little
39
Table IV-3
Per Acre Yield of Potatoes on L.L and in U.S.
1955-1979
Yield/acre
L.L (Fall) U.S. (Fall) Total U.S.
Year 11l (Z) (3)
1955 Z15 169 161
1956 Z40 191 176
1957 Z35 185 173
1958 Z50 196 181
1959 ZZO 188 184
1960 Z70 185 184
1961 Z58 196 196
196Z Z85 197 194
1963 Z65 Z06 ZOl
1964 Z55 185 185
1965 Z90 Z14 Z10
1966 Z55 Z13 Z10
1967 Z35 ZlZ Z10
1968 Z65 Z14 Z14
1969 Z60 ZZ3 ZZl
1970 Z70 Z33 ZZ9
1971 Z30 Z36 Z30
191Z Z07 Z46 Z36
1973 Z15 Z33 Z30
1974 Z50 Z53 Z46
1975 Z'GO Z64 Z53
1976 310 Z69 Z60
1977 315 Z70 Z61
1978 Z65 Z80 Z66
1979 Z95 Z77 Z69
Average Z57 ZZZ Z15
Standard
deviation Z8.5 33.1 3Z.0
Source: U.S. Department of Agriculture. Potatoes and Sweet Potatoes. Crop
Reporting Board, Washington, D.C.
1. Long Island Fall Crop.
Z. U.S. Fall Crop including Long Island.
3. All U.S. production.
clay. Farm soils contain little organic
litter, and biological activity is generally
low. In consequence, soluble pesticides
whose decomposition depends primarily on
biological activity can be mobile and
persistent in Long Island soils. As a
result, an increasing number of pesticides
have now been found in ground water
underlying or adjacent to farm,ing areas.
To the potato growers on the North
Fork, the discovery of pesticides in
ground water and the subsequent
unavailability of effective pesticides,
have been unfortunate. The farmers'
attempts to control pests using less
effective pesticides has inevitably
increased the number and volume of
sprays. For example, surveys of farm
costs on Long Island showed that the
average cost of pesticides was $126 per
acre in 1976, the first year aldicarb was
widely used. In 1981 when aldicarb was
no longer available the average cost was
$291 (Synder, 1977 and 1982), an increase
of over 130% in only five years. Inflation
accounts for approximately 40%, and the
remainder represents cost increases due
to the cbaiage in pesticides and the
increasing amounts needed to compensate
for their lower efficacy.
There is now a critical need to
develop effective techniques to control
pests if potato farmers are to sustain
adequate production and remain in
business. At' the same time, further
serious contamination of ground water
used for drinking water by new application
of pesticides is unacceptable to all
residents of the. North Fork. Given this
double constraint, the need to control
pests, and the need to protect ground
water quality, Cornell University and its
Long Island Horticultural Research.
Laboratory have instituted the Integrated
Pest Management (IPM) program, a
program of research to discover new
methods of pest controls for Long Island's
potato farmers. These pest controls
include biological, cultural, and genetic
methods as well as chemical ones in order
40
to provide control techniques with
minimal effects on nontarget organisms
and on the environment.
Two overall types of methods for
managing potato pests can be
distmguished: (1) direct pest control
techniques for use in potato production,
and (2) alternate cropping systems.
Direct techniques include eliminating
unnecessary chemical spraying by
determining action thresholds and by
conducting field scouting to determine
precisely when these damage thresholds
have been exceeded. Research is being
carried out on biological control
possibilities, including suppressing beetles
with the Beauvaria bassiana fungus.
Cultural practices such as killing the
potato vines earlier in the season to
reduce food available to the beetles also
are being investigated. Genetic research
is looking into ways of making the potato
plant more resistant to beetles, including
breeding for the sticky hairs present in
some wild species which can trap insects
and cause them to starve.
Alternative cropping systems that
could reduce the need for pesticides
include crop diversification and annual
crop rotations. Wright et al. (1983) report
that on three farms out of four, potatoes
grown on fields previously used for another
crop had lower populations of the
Colorado potato beetle than did fields on
which no rotation took place. On the
fourth farm, the overall number of the
Colorado potato beetle were so low that
differences between the rotated and
nonrotated fields were immaterial. Crop
rotation therefore could reduce the need
for pesticides by reducing insect numbers
and by slowing the insects' development of
resistance which necessitates increasing
chemical doses over time. Crops to be
rotated would need to be carefully chosen
to maintain farm income levels, as
addressed by Lazarus and White (1983).
Further information on Long Island's
IPM programs is contained in Appendix A.
41
Chapter V
EFFECTS OF OTHER LAND USES ON GROUND-WATER QUALITY
The previous two chapters have
addressed the effects of housing and
potato farming on ground-water quality in
Southold. Although these are the Town's
two most prevalent land uses, many other
uses exist now or are being considered for
the future. In this chapter we present the
results of W ALRAS simulations of nitrate
leaching concentrations from these other
land uses. The numbers in this chapter
represent broad estimates with much
greater uncertainty than in the potato
simulations because similar field data are
,not available for verification of our
models. The results presented here
therefore represent only a general
indication of nitrate levels, and are meant
to be a first step indicating where more
work is needed.
EzistiDg Land Uses
In order to simulate an example of
existing land uses in Southold, we chose
an area extending across the North Fork
along Depot Lane, bounded by Alvah's
Lane, Linden Avenue, and Cox Lane.
Land uses in this area include a variety of
agricultural crops as well as housing, a
golf course, and horse pasture (Figure V-
I). The soils are predominantly Riverhead
and Haven sandy loams, with smaller
areas of Carver and Plymouth sands or
Scio silt loam (Figure V-Z).
Simulated nitrate concentrations in
recharge from these existing land uses are
shown in Figure V-3. A large portion of
the land area has recharge c01!lcentrations
in the 7.5 to 10.0 mg/l range. This area
consists primarily of potato fields, and
nitrate levels can be reduced by changing
the fertilization practices, as discussed in
Chapter IV. The areas with recharge
concentrations exceeding 10 mg/l are
either located on Carver and Plymouth
sands or are used for sod farms, nurseries,
horse pastures, or fields of mixed
vegetables or cole crops. Those with low
nitrate recharge concentrations (less than
5.0 mg/I) 'are either vacant land, fields
being rested by year-round growth of
grain, or low-density residential areas.
Specific recharge concentrations for
each of these land uses are shown in Table
V-I. It should be kept in mind, however,
that these numbers are somewhat
speculative since for uses other than
potato farming no field data are available
for verification of the simulation results.
Field data collected in 1981 by the
Suffolk County Department of Health
Services on nitrate concentrations in
ground water below Depot Lane are shown
in Figure V-4. As with the simulated
recharge values, the ground-water data
showed a wide spread of values, ranging
from 0.3 to 13.0 mg/l nitrate. The lowest
,
of these occurred at the ground-water
divide, below an area used for vacant land
and houses. The highest was below an
area used for potato farming.
Possible Future Land Uses
Possible future land uses for the
Depot Lane area include continuation of
exis ting uses, changes in agricultural
crops, or increases in residential
development. Continuation of the
existing potato farming, with revised
fertilization practices as suggested in
Chapter IV, would be consistent with
ground-water quality. Only the portions
of fields on Carver and Plymouth sands
would still have unacceptably high nitrate
leaching concentrations. Other
agricultural crops such as mixed
A - AGRICULTURE
Ap - Potato
Av - Mixed Vegetables
Ag - Grapes
Ao - Orchard
An - Nursery
As - Sod
Ah - Horse Pasture
R - RESIDENTIAL
Rl - 0 to 1 D.U./Acre
R2 - 2 to 4 D.U./Acre
~
&
co c
~
't'
~
,
Ap
..
N
LEGEND
C - COMMERCIAl/ INDUSTRIAL
I - INSTITUTIONAL
PIc - PARK/GOLF COURSE
V - VACANT
RB - RECHARGE BASIN
~
~
~
t:
" Iv
i ~
.' 0
J'
'"
ij
StALE
\
r_'__
o '000 1000 SOOO
'1000l'I:ET lrfOIlTH
FIGURE V-I. LAND USES IN THE DEPOT LANE TRANSECT AREA. SOUTHOLD. N.Y.
,@
,:j
..0 0
~
'"
.@' HR
;1:>'"
~ ~PC
~
~
HR
~
HR
PC~Sm
~C
~so
Q
~
HR
HR
.t
~
~
S'
d'
~
'"
iJ
LEGEND
HR -RIVERHEAD and HAVEN SOILS
PC -CARVER and PLYMOUTH SANDS
SO -SCIO SILT LOAM
o -OTHER (Beachaa. Cut and All,
Made Land, TIdal Marshea)
I
o
. SCAlE
toOO 2000 5000 .000 nET
\
NOfITH
FIGURE V-2. SOIL TYPES IN THE DEPOT LANE TRANSECT AREA. SOUTHOLD. N.Y.
~
.,di
~
""
~
...
~b
o
...
..
..
LEGEND
0.0' 2.5 MGIl
~"'~'i...".
.~ '''~''''
.:.:;.:;.-.,:-
~
:.:::.,: 60
":..:. .
7.6 MOIl
J
't'
~
J
.t
R
,,(j
~
2.6 5.0 MOIl
~ 7.6 . 10.0 MGIl
. > 10.0 MOIl
D Not Simulated
(Concentretlons In M11llgrems Per UterI
ICAU
~
~---
. ,...
....
....
4000"UT
NOIIITH
FIGURE V-3. RFSULTS OF NITRATE SIMULATIONS IN THE DEPOT LANE TRANSECT
AREA. SOUTHOLD. N.Y.
,-.,.,....,...,..,'....,.,
;.,:..,..~,,--,...,- """.""":-
45
Table V-l Simulated nitrate leaching concentrations for various land uses in
Southold, N.Y.
Nitrate Leacbed (mRfll
Total
Fertilizer Riverhead and Carver and
Applied Haven Sandy Plymouth
(lb Nt A/vr) Loam Sands
Crops
Cole Cropsa 140 10.2 12.0
Mixed Vegetablesb 120 10.8 12.0
Potatoes 175 8.1 16.1
GrainC 0 2.5 1.3
Nurseries 250 11.5 14.2
Orchards 100 6.4 12.0
Vineyards 30 5.6 5.4
Sod
1st Year 214 8.5 11.4
2nd Year 289 19.6 21.5
Other Land Uses
Horse Pasturesd 0 2.1 2.2
Golf Coursese ' 63 7.6 8.5
Parks 48 4.1 4.3
Vacant Land 0 0.9 0.9
(Unfertilized
vegetation)
a) Cole c::ropa are thOM in the cabbage famDy, including cauliflower,
cabbage, bluael 8pl'OUt.. and broccoli.
b) . Mb:.d.' ft88tables ~ defiDed hee to iDc1ude a variety of vesetables
&rOwn on Loq: IalaDd. lnclucllns .weet com, melons, map beau, peppen,
cucumbers, JNmpkiDa, tomat~, ete.
c:} Grain 11 repNHDted here u . field. beiDa ralted. from regular potato
pZ'OductioD, abt u commercial p'ain prod.uction.
4). Although DO fertWaer ia applied. u 1Uch, the hones depl>>it nitropn iD the
fOl'm of mUUll'e and urine durtng the Mnn montha that they graze in the
pum...
e) TheM DWDben are aver&fled. over the entire land. &l'e., but for dmu.1ation
pul'pO'" they wen broken into dlUel'ltDt fertiUaatloD rata for different
land categories IUc:b u fairways. 11''''' and tees.
100
SO ..
..
N
"
~
60 ,
..
40
20
.I.S
MSL
ORSXlN RD.
N
..
N
"
~
,
..
MIDOLI LIAR
_0
M
..
N
"
~
J.
-20 \
,
\
\, 3.9
'. 5.4
'.
6.5
6.9 10.0
'.5
0;
e -40
7.1
6.9
8.6
~
H -60
~
~
;: -80 :).3 2.4 8.0
.SALl' WAn;\
-100 WBDGB J J~O 0.2
---- ? --- -----1
5.2
9.3
11.0
8.9
48
MAIN
_0
"
~
"
"
~
,
..
..
~
N
"
~
,
..
c
..
N
"
~
J.
1l.0
0.3
7.6
0.8 13.0
0.5 9.0
0.6 4.5
7.6
8.7
8.2
6.1
I
,
I
4.2
6.2
6.0
I
,
6.,0
I
1.6 I
-120
____~ 2..4
CLA.Y ~y - - ---...........
....
?.... 0.2
-----
/
L' SALT WA'l'BR
, -- -..RD<1'!....-
-140
-160
Concentrations is ppm (Iq/l)
o 1 2 3 4 5
7
DISTANCE FROM. NORTH SHORE (1000 P'TI
6
FIGURE y...: NORTH FORK TRANSECT
5.2
,
8
9
10
II
12
13
14
15
16
17
18
19
20
(Taken frea: RelD9rt on tne OCcurrence end Movament of Agricultural Oleaicals in Groundwater: North Fork
of Suf'foUt COunty, Suffolk County Dep&rtaent of Health services, Auqust, 1982.)
vege.tables or cole crops appear to
produce recharge concentrations in the
same range as those from potato. fields,
and vineyards and orchards appear a bit
lower (Table V-i). Simulations of sod
farms show extremely high leaching rates
as a result of the large amounts of
fertilizer applied for rapid growth of
quality turf.
Although residential development
appears beneficial from its relatively low
nitrate concentrations, housing and
associa.ted services such as gas stations,
dry cleaning operations, or other
commercial development can contribute
.substantial amounts of other chemicals to
ground water, including organic
contaminants as discussed in Chapter III.
For protection of ground-water quality,
residential development should therefore
be kept at a low density, preferably in the
range of one or fewer houses per acre.
Because the highly permeable
Carver and Plymouth sands are not highly
fertile, they commonly are used for
hausing rather than agriculture when they
cover a large enough area, as in the
Cutchogue Harbor section of the Depot
Lane transect (Figures V-l and V-Z). The
high fertilization and irrigation rates
needed for maintaining lawns on these
sandy soils probably leads to nitrate
leaching concentrations far in excess of
those predicted here and in Chapter m for
residential development, but the lack of
field data on either turf or septic system
functioning. on the sandy soils precludes
further refinement of our simulation
results. In general, the sandy soils would
best be kept in unfertilized open space
uses such as vacant land or parks for
protection of ground-water quality. The
more fertile and less highly permeable
Riverhead and Haven soils, on the other
hand, are suitable for a wide range of
agrit:ul.tural and residential uses.
Chapter VI
47
ALDICARB CONTAMINATION OF SOUTHOLD'S GROUND WATER
Aldicarb Use m Southold
Aldicarb is a highly toxic
insecticide, marketed under the brand
name of Temik, and used throughout the
United States on crops including potatoes,
cotton, sugar beets, and oranges. Potato
farmers in Southold began using aldicarb
in 1975 and found it highly effective in
controlling the Colorado potato beetle
and golden nematode. As can be seen
from Table IV-4, there was a dramatic
increase in yields during the four years
aldicarb was used compared to the
preceeding five years. However, aldicarb
and its byproducts are highly soluble and
weakly adsorbed to soil, and it was
expected that they might not fully
degrade before reaching ground water
(Porter and Beyer, 1977). When this
proved to be the case, aldi.carb was
removed from use on Long Island in 1979,
leaving the potato farmers with no
equally effective means of combating the
beetle and nematode problems.
Since that time, aldicarb
contamination of Long Island's ground
water has been found to be widespread.
Of the nearly 14,000 Suffolk County wells
tested as of June 1983, Z8.9 percent had
detectable aldicarb concentrations with
15.1 percent exceeding the 7 ppb drinking
water guideline for New York State; 15.5
percent of the 5,784 wells tested in the
Town of Southold exceeded 7 ppb and an
additional 13.Z percent had detectable
aldicarb concentrations lower than this
amount.
In this project the goal was to trace
the attenuation and movement of aldicarb
to the ground water. Within the root zone
and unsaturated zone, water movement
was calculated first, then aldicarb
movement was computed based on its
solubility and adsorption coefficient.
Depot Lane TraDsect
In 1980 the Suffolk County
Department of Health Services had a
series of geologic test holes and
observation wells drilled along Depot
Lane in Cutchogue in order to obtain
information about how aldicarb and other
contaminants move through the North
Fork's aquifer. The transect cuts across
the North Fork from north to south and
runs parallel to ground-water flow in both
the northerly and southerly directions.
Private wells were sampled by the County
in the Spring of 1980, and the observation
wells were tested a year later. The
results are shown in Figure VI-I. A1dicarb
contamination was found up to 100 feet
below the water table near the center of
the transect and at shallower depths (up
to 40 feet below the water table) at the
narthern and southern extremities, with
concentrations ranging from one to 149
ppb.
. Aldicarb Simulation
The Depot Lane transect was
divided into 13 areas (Figures VI-Z and VI-
3), and the farmers were surveyed about
their aldicarb use on fields within each of
these regions. Results are shown in Table
VI-I. .
For our simulations, the adsorption
partition coefficient was set at 0.09 in
the root zone and at 0.0 below the root
zone, indicating that only a small percent
of the aldicarb contained in the soil water
would be adsorbed to soil particles in the
root zone, and none below this zone.
lOa
Oregon Rd.
N
80 Q)
.. on M N
Q) Q) Q) ....
N N '" r-
.... .... .... I
60 r- r- r- ..
I I I
.. ..
40
20
L. I.
MSL
.
\ (*.) . 40
-20
\ (.)
f;
~ -40 \ (.)C~, ,
15 -60 \ (.)!:l,
H
.. . ,
" \
:>
~ . .
-80 \.
.. .
SALT WATER \ .
-100 -~~- 1..) .
---
(.)
84 (') ,(1)
.
('J ,
,
,
,
,
Iol'd'dl. L1RR
RO.d
M.ln
Ro*d
0 Q)
Q) r-
'" '"
.... ....
r- r-
J. I
4) (89) (55) (')
(* ) (1) (149(~h27) (:)
(~
l'ftl 18
(83) C')
. (.) . .
.
CUTCHQGUE
HARBOR
.
I
.
?
I
.
4
,
..
CD
I
1
3
,
?
I
,
~
.
/
-120
. .
------1------.L.- 1
ClAY aoUNDA~
,
/
, &ALT WATER
__ L WEnGE
? ---';)--
Concentrations of total aldicarb (ppbJ.
-140 . None detected.
Private well sample (depth may be inaccurate) .
-l60
0 1 2 3 4 5 6 7 8 9 10 11
,
?
...........
1-
---- -
---
12 13
DISTANCE FROM NORTH SHORE (1000 FT)
14
15
16
17
18
19 20
(Taken from:
Figure VI-1. ALDICARB CONCENTRATIONS MEASURED IN WELLS ALONG THE
DEPOT LANE TRANSECT~ SOUTHOLD~ N.Y.
Re ort on the Occurrence and Movement of A ricultural Chemicals in Groundwater: Noeth Fork
of Suffolk County, Suffolk County Department of Health Services, August, 1982.)
#~
~
'"
~
,
.,.'"
(l
"
2
4
6
8 /
,9/101
, , ,
, ,
,
.
...
IIoIfI St.
ct
~
~
,S-
o
F
~
iJ
I
o
SCALIE
. .
1)00 2000 !OOO 4000 'EET
\
NOJIlTH
FIGURE VI-2. AREAS USED FOR ALDICARB ANALYSIS ALONG THE DEPOT LANE
TRANSECT, SOUTHOLD, N.Y.
z
o
....
""
>
W
...J
u.J
\
\
-40 \
'.
\
.
\
\
-100~_~_~
-------- --------
el.,...........'
-eo
",........
,
/
/
/
/
/
-eo
-,..
-'-
/
-,..
-
-------
_ _.L _S.~I~ ~~.
-1
o 2 3 4 15 . 7 8 I 10 11 12 13 14 11 " 17 111 19 20
DISTANCE FROM NORTH SHORE (1000 FT,)
FIGURE VI-3. SIMULATED ALDICARB PL~~S ALONG THE DEPOT LANE TRANSECT,
SOUTHOLD. N, y, CIRCLED NUHB,ERS REPRESENT CONCENTRATIONS
IN PPS.
Table VI-I
Aldicarb use on fields along the Depot Lane transect, 1975 to
1979
Area t
Aldicarb Applied
(lb active inlZ1'edient/ A)
1975 1976 1977 1978 1979 Total
0.5 0.0 0.0 0.0 0.0 0.5
Z.5 0.6 1.0 1.0 1.0 6.1
0.4 0.7 1.1 1.1 1.1 4.4
0.1 1.4 Z.3 Z.3 Z.3 8.4
1.1 1.9 Z.4 Z.4 Z.4 10.Z
0.5 1.8 Z.5 3.7 3.7 lZ.Z
0.0 0.0 0.0 0.0 0.0 0.0
1.7 Z.O Z.O Z.9 Z.9 11.5
1.6 3.7 3.7 4.6 4.6 18.Z
Z.1 Z.6 Z.6 3.8 3.8 14.9
Z.1 4.0 4.0 5.Z 3.7 19.0
0.0 O.Z 0.2 O.Z 0.0 0.6
1.7 1.7 1.7 1.7 1.7 8.5
1
Z
3
4
5
6
7
8
9
10
11
1Z
13
These numbers were calculated from a
linear regression relating adsorption
coefficients to soil organic matter
derived from the results of four field and
laboratory experiments (Kain and
Steenhuis, 1982).
The greatest uncertainty in
modelling aldicarb is its rate of
attenuation in the root zone, unsaturated
zone, and saturated zone. The half-life,
or time that it takes for half of the
aldicarb to decay to nontoxic byproducts,
is shortest in the root zone where
microbial populations speed the decaying
process, and longest in the saturated zone
because of the lower temperatures and
low rates of microbial activity.
Unfortunately, laboratory and field
experiments on these half lives are few,
and the results are inconclusive. A
previous review summarizing studies on
aldicarb degradation in a variety of soils
showed ranges in half-lives from one to
231 days (Kain and Steenhuis, 1982). In
our simulations, a 50 day half-life was
used for the root zone. This w,as
increased to 100 days for the next 30
centimeters in depth because microbial
populations diminish with increasing depth
(Pacenka and Porter, 1981). For the
remainder of the unsaturated zone, a
half-life of 10 years was used. The 50 day
root zone half-life is from Kain and
Steenhuis (1982). The other numbers were
derived by calibrating our model with
field data from a potato field on the
North Fork studied by Intera (1980) and a
deep soil core taken at the Long Island
Horticultural Research Laboratory
(unpublished data).
The simulation results indicating the
dates and concentrations of aldicarb
leaching to the ground water are shown in
Table VI-2. According to our simulations,
51
all aldicarb that will reach ground water
is estimated to do so by 1984. The
average concentrations of aldicarb
recharging ground water were derived for
each area by calculating total amounts of
aldicarb applied, subtracting the amounts
taken up by plants or degraded in the root .
zone or unsaturated zone, then dividing by
the total water recharged. In all areas
except *12, where very little aldicarb was
applied, the simulations show average
aldicarb concentrations reaching ground
water to be well above the 7 ppb drinking
water guideline. How long they will
remain higher than the guideline depends
on ground-water flow and on aldicarb's
half-life within the saturated zone. For
areas along the shoreline, the
contaminated ground water will probably
be "flushed out", or discharged to surface
water in a shorter time than it would take
for the aldicarb degradation to occur.
For inland areas, aldicarb's half-life in
ground water will determine how long the
contamination will remain.
Laboratory estimates of the half-
life of aldicarb in ground water have
ranged from less than one to greater than
ten years, depending on pH, temperature,
and experimental procedure (Chapman
and Cole, 1982; Hansen and Spiegel, 1982
and 1983; Lemley, 1983).* Table VI-3
summarizes the available laboratory data
on half-lifes of aldicarb and its
degradation products in water at various
pH's and temperatures. Field testing has
shown that virtually all aldicarb oxidizes
to the sulfoxide or sulfone forms before
reaching ground water, so it is the half-
lifes of these two compounds that are of
concern in the saturated zone.
By extrapolating the available
laboratory data to 150C and pH 6 to
represent ground-water conditions typical
* Prior to the availability of this laboratory data, Intera (1980) had derived
a zero decomposition rate, or infinite half-life for aldicarb, based on their
simulation results rather than on any laboratory measurements.
52
Table VI-2 Simulation results sbowing dates tbat aldicarb will reach ground
water and its average concentrations in ground water below tbe
Depot Lane transect in Soutbold, N.Y.
Area
~
Year
Aldicarb
First Reaches
Water Tablea
1
2
3
4
5
6
7
8
9
10
11
12
13
1979
1979
1979
1979
1979
1977
N.A.c
1976
1976
1976
1976
1977
1976
Year
An
of Aldicarb
Reaches
Water Table
Average
Aldicarb
Concentration
. Recharging
Ground
Waterb
1979
1984
1984
1984
1984
1982
N.A.c
1981
1981
1981
1981
1980
1981
41
52
24
39
56
62
N.A.c
78
110
99
118
5
62
a) This gives tbe year in which aldicarb would first have reached tbe water
table aecording to tbe simulation. Note that the greater tbe distance
between tbe Iud surface and the water table, the longer the time between
when aldicarb is applied at the surface and when it reaches the water table.
b) This is tbe average concentration of aldicarb in water entering tbe saturated
zone between tbe time when aldicarb first reaches tbe water table and tbe
time when it has all reached tbe water table.
c) Not applicable because no aldicarb was applied. to this section.
of Long Island, estimates were made of
the half-lifes of these two compounds.
For aldicarb sulfoxide, a range of eleven
to sixteen years was estimated, and four
to nine years for aldicarb sulfone. These.
two compounds are found in
approximately equal proportions in the
ground water, so averaging their half-lifes
yields a rough overall estimate of tbe
breakdown rate to nontoxic compounds.
In this manner an overall average half-life
of ten years was obtained. A great deal
of uncertainty is contained in this number
botb because of the numerous
extrapolations required and because the
laboratory experiments greatly
oversimplify the processes at work under
actual ground-water conditions.
A ten year half-life would mean a
period of. decades before tbe aldicarb
plume woUld decay below the 7 ppb
drinking water guideline in ground water
53
Table VI-3. Laboratory data on half-Ufes (in days) of aldicarb and its
degradation products in water at various pH's and temperatures.
pH
Source
5.5 6.0 7.0 7.5 8 8.5
Aldicarb
150C 3Z40 1900 170 b
2.5OC 2.66 2.45 2.66 a
Aldicarb Sulfoxide
150C 440 360 10 b
NA NA 73 c
42.2.1 42.2. 42. d
2.5OC 679 161 2.3 a
NA 154 2.2. c
Aldicarb Sulfone
150C 450 12.5 5 b
NA 2.72. 52. c
1458 145 15 d
2.5oC 42.0 77 10 a
NA 84 10 c
597 60 6 d
Sources:
a) Chapman and Cole'(1982.)
b) Hansen and Spiegel (1983)
c) Hansen et al. (1983) (Note: Values labelled "NA" are not yet available
but will be at the conclusion of the experiments.)
d) Lemley (1983) (Note: These data are extrapolated from experiments
conducted at pH's 11 to 13.)
. underlying the Depot Lane transect and in
other areas of Southold which had similar
aldicarb application schedules. This half-
life estimate is too uncertain, however,
for it to be reliably used for water quality
planning purposes. As a result, Cornell
University is embarking on a more
extensive study which will help to better
define how long aldicarb will remain a
problem in Long Island's ground water.
54
55
Chapter VII
PESnCIDE SCREENING TO PREVENT GROUND-WATER CONTAMINATION
Southold's ground water has become
contaminated by aldicarb and several
other pesticides; including carbofuran,
dacthal, dinoseb, and 1,2 dichloropropane.
For aldicarb alone, millions of dollars
have been spent by govemment and
industry to test, treat, and study the
ground-water contamination. Ultimately,
the cost of clean-up entails expensive
treatment of drinking water supplies, a
measure which in itself does little to
discourage further degradation of ground-
water quality. A far more cost-effective
measure would be to prevent
contamination through methods in~g
thorough screening of new pesti<ri4es
before they are used.
Traditionally, pesticide manufac-
turers have used field experiments to
evaluate the environmental safety of
their chemicals. There are problems in
relying exclusively on field work for
individual locations and soil types to
provide universally acceptable
assessments of chemical fates. In
particular, the spatial heterogeneity of
physical, chemical and biological field
processes, and the temporal variability of
climate, make it difficult to obtain an
accurate field description of pesticide
distribution. It is virtually impossible to
reproduce these variable field conditions
in the laboratory, or to extrapolate
laboratory results and apply them to field
conditions. In addition, testing for
contaminants in concentration ranges of
parts per billion requires sophisticated
technology, and in some cases the water
quality standard for a chemical is lower
than the analytical detection limits.
There is a marked tendency to address
these problems by doing more sampling,
extending field experiments over longer
periods, and in general imposing greater
requirements . on pesticide evaluatory
procedures.
Because of the limitations of
traditional field trials in testing all soil.
and climate effects on the fate of new
pesticides, interest has developed in
complementing these experiments with
computer simulation of chemical
movement through the soil profile. Such
an approach can be useful in identifying
which pesticides are most likely to leach
to ground water and therefore require the
dosest scrutiny before widespread use.
The Budget Approach
All of any pesticide that is added to
an ecosystem is removed by transport,
<:;I1emicallv converted into other
substances, or built up in storage. For a
given ecosystem, such as the top foot of
soil in a potato field, we can describe a
"budget" which itemizes the sizes of the
source, fates, and net buildup of a given
chemical over some period of time.
Figure VII-I illustrates a generic model of
pesticide behavior, and Table W-l shows
the budget in corresponding tabular form.
An evaluated budget for a given
combination of input, management
practices, and environmental factors can
be tested for "safety" by scrutinizing
specific terms that are associated with
environmental standards. For example, if
we specify that the concentration of a
substance may be no greater than 10 ug/l
in recharge, as an annual average, we can
calculate an annual "allowable load" in
recharge by multiplying this
concentration times the volume of
recharge water. . If we have SO acre-
inches of recharge water, the
56
\
!
Photodecomposition
volatilization
ApplicAtion,
fallout
Application,
fallout
Harvest,
decomposition
Decomposi tien,
volatilization
RunQff
and.
lernq
EXPLANATION
--"
.
,'I/i>.i<."_
Flow
-
,
FIGURE VII-I.
GaMII/lJIIC _L OF PES<TlCI'BE BEHAVIOR
I H THf RllBT ZOHE.
corresponding allowable load would be 10
ug/l times 50 acre-inches, totalling 0.11
lb of the substance per year. This figure
can be compared to the budget's
"leaching" term to assess whether there
could be a problem.
B'uJdhlll Mathematical Moclela into the
Pesticide Reaiaf:ratioD PHI<. BII
Models improve' the development
and registration process in five ways by:
Budgets are constructed using a
combination of field data and
mathematical models that synthesize the
data into a coherent whole. The following
sections discuss how such models can be
developed interactively with field
experimentation.
. Forcing completeness of
investigations;
. Yielding insight into the
relative importance of
different processes affect-
ing the fate of the applied
chemical;
. Providing explicit estimates
of uncertainty;
.
Determining
tance of
relative to
decisions; and
the impol'-
uncertainties
pending
.
Producing
objective,
conclusions.
standardiz ed,
and audit able
To achieve these goals, model
development and use need to be
incorporated into the earliest stages of
the pesticide review process, as outlined
in Figure vn-Z.
57
Guiding Field Investigations
Field investigations usually reflect
the perceptions and biases of the
investigator about which processes are
most significant and which are least well
known. The most significant and
uncertain processes according to this
conceptual model then receive the most
intensive observation. Early use of an
objective mathematical model can help to
force completeness of the field work.
Since many processes affect the fate of a
pesticide in the field, it is easy to omit
elements of the soil-water system which
subsequently may be found to have an
important role.
Table VII-l
Buqet corrapoDdiaa to Model... Figure I
On Plants Ibl AI.. Undiaolved !bIAl..
IN. Application IN. Application
Fallout
OUT: Dissolution
OUT. PhotodecompotitioD
VolatiliaatioD CHANGE IN STORAGE:
Wuhaff
Intake by plants
CHANGE IN STORAGE: In Soil Solution Ibl AI..
IN. DiuoluttoD.
Mineralization
In Plants Ibl Alp Root exudation
DellOtptioD
IN: Intake from surface. Wuhalf
Uptake from soil
OUT: Decomposition
OUT: Root exudatioD Volatilization
Death Leaching
Harve.t Runoff
Decomposition Uptake by plants
Immobilization
CHANGE IN STORAGE: Adsorption
CHANGE IN STORAGE:
SoU Organic Matter Ibl Alyr
Adsorbed onto Soil IbIAl..
IN. Plant death
Immobiliaation IN. Adsorption
OUT: Minel'aU:r.ation OUT: Desorption
OecompMition Decompoaition
CHANGE IN STORAGE: CHANGE IN STORAGE:
reviews
lab experiments
.
.,(J''''
-..-......
58
alternative
mathematical models
FIGURE VH-2
IN'J!_n'l!Il OF MA'~H_1TIC"'L /llilDBLS INTO
1'ItE pml'CIDE eYALlJAnON PRGGESS.
An objective mathematical model of
the field processes also can help to
determine which of the processes deserve
closer scrutiny. Initially, laboratory
experiments, technical literature, and
other indirect sources can be used to
create a formative data base. Then, the
model can be used tgCOnf;l.uct a sensitivity
analysis within the plausible range of the
parameters. The range of the resulting
budgets will yield estimates of
uncertainty and significance for each
term.
Figure VII-3 shows the result of a
simple sensitivity analysis for the fates of
aldicarb. In such a simplified system,
only a few parameters need to be varied
to obtain a feeling for the overall
uncertauity. Here, climate, plant uptake,
and microbial decomposition parameters'
were varied. Despite inadequate field
data for these parameters, the sensitivity
analyses show that even under very
favorable assumptions, about a third of
the pesticide can be expected to leach.
This amount would lead to a
concentration in ground water
considerably higher than the 7 ppb N.Y.S.
guideline for drinking water, so an
analysis of this type could have been used
to predict and prevent Long Island's
current aldicarb problems.
Table VII-;/. inventories the data
requirements of an early-stage model.
Considerable understanding can be gained
using only existing data sources.
.~
~
:B
........
i:O.5
tlili
"'...
~
~
e~
........
~~
e ::;0.5
Hili
$...
~
Figure VII-3
1.0
Sen$itivitv of Annual Aldlcarb Mass Balances to DecomPOsition and plant UPtake Para~et~~s
Leached
0.0
0.0 decay rate
Il/day)
0.006
1.0
plant uptake parameter -
0.0
Leached
0.0
0.0
0.006
Leached
0.0
decay rate 0.006
Il/day)
plant uptake parameter a
0.033
Leached
0.0
0.006
Leached
Taken up by Planta
0.0
decay rate 0.006
(l/day)
plant uptake parameter =
0.067
Leached
Taken up by Plant.
0.0 0.006
Taken up by Planta
0.0 decay rate
(lI~ay)
0.006
<It
...
plant uptake parameter =
0.11
Leached
Taken up by Planta
0.0 0.nn6
60
Table VIl-2
Minimal Data Req\iliements for W ALRAS
Regional EvaluatioD of
Pesticide Movement and Fate
aOOT ZONE
UNSATURATED ZONB
Water budget-related data
Water Movement
Soil eharactemtic.
Soil characteristics
Texture
Moiature content at field
capacity
Moi,ture content at wilting
point
. Time to dzain from
.saturation to field
capacity
Moisture content at Cield
capacity
Depths to impermeable
laye" and water table
Chemical behavior
,Vegetation characteristics
SoU characteristics
Cover extent and density,
over time
Root %ODe depth, over time
Runoff-production
parameters (also
related to soil)
TextW'e (especially day
content)
Chemical and microbiological
characteristics
Precipitation amounts and
timing
Air temperatures
Potential evapotranspiration
Potential snowmelt rate
pH
Degradation rate
AdaoJ'pticm parameters
Dispenion puameten
Climate data
Crop and soil managemen t
practices
SA TURA TED ZONE
Irrigation amount, and
timing
Water Movement
Cbemical Budgets
Geologic data
Soil cbaracteriatics
Texture (especially clay
content)
Organic matter' content
Permeability
SatW'ated bydraulic
conductivity
Depth to impermeable layer
Storage coefficient
Chemical and microbiological
parameters
Chemical Behavior
pH
Degradation rate
Disaolution rate
Adsorption parameter' (related to
organic matter)
Plant uptake parameter,
Geologic data
Texture (especially clay
content)
Chemical and microbiological
data
Management practices
Dates and amounts applied
Depth of incorporation
pH
Degradation rate
Adsorption parameters
Dispemon parameters
Impt-o,,~ Budget Estimates DuriDg Field
"'ark
The range of uncertainty included in
the early sensitivity analysis will narrow
considerably, if the field work has been
designed and conducted well. As field
results become available, the range can
.be reevaluated.
At this point, the pesticide's
potential environmental impact can be
compared with some environmental
guideline such as the drinking water
guideline. If initial field experiments
show a clear-cut acceptable or
61
unacceptable impact regardless of the
degree of uncertainty, then an early
decision can be made. If the range of
estimated impact still includes both
possibilities, further field experi-
mentation would be necessary to reduce
the uncertainty until a clear-cut case one
way or the other is achieved.
Figure VD-4 illustrates these
examples, showing when a particular
pesticide can be accepted or rejected for
widespread use and when further analysis
is needed. Such a "multi-track" scheme
would save time and avoid unnecessary
expenses by focusing detailed analyses
, , --_. REJECT
" ~
A 5! _______i~a:~__ impact WITHOUT FURTHER
:l!~ limit FIELD WORK
acceptable
impact
T~
..
0 ACCEPT
" ~
B a fo-- ------ ---- WITHOUT FURTHER
~ .~
~
:Il~ FIELD WORK t} ranqe
of
Time estimated
impact
,
..
0 .+-------
" . ACCEPT
H
C ~.... AFTER SUBSEQUENT
~
"..
Z 0 FIELD WORK
TilllO
.. +Jm-
0
" . REJECT
a
D ~.... AFTER SUBSEQUENT
.
:l!~ FIELD WORK
Time
FIGURE VIl-4.
RELATIONSHIPS AMONG IMPACT LIMITS, UNCERTAINTIES,
AND DECISIONS ABOUT PESTICIDES FOR POTENTIAL USE
IN SOUTHOLD, N.Y.
primarily on those chemicals for which
the environmental impacts are most
unclear. The pesticide registration
process could be ,conducted more rapidly,
and ground-water quality could be more
effectively safeguarded because field,
laboratory, and computer analyses could
be directed toward those pesticides for
which the leaching potential is most
uncertain.
i
L
n'.""""''''''',,'''';''''''''''-''
.--~.,'t.
rDGMlea, _4
r.....y data
requir_ents
"".",,,.,-~.,,,
,'~,....,""'~ "_.""'0::'-'--'
8,2
Figure VlI-5 outlines this proposed review
procedure for pesticides, showing how a
mathematical model based on existing
field and laboratory data can be used to
determine when a chemical can be
accepted or rejected, or when further
lmalysis is needed.
,,,,,.,,, '1',,"_:F'.;.::'-"'-
:~..t ....tli.1l uui t....~l uait.s',
.... ~a.-u. eoope.riJDea-trti d...
.,~-"
"";"",:",,,,,,;'i-',,",,~...,_.^..'L"-'
__!i~ wait.6r 8.-.__..... or erib6r ia
"ll'o'*,W""'-"~ '''''''''~'
~. tcDltoa,l %!~lJ. \Mit:fK tl!lCiler
~ Gll.i....t:. :fi'(it.r eaeh witt af
.... aM. t1:me
-~:;;:'M;t~;:;.",,-.,<,.~';
1;'--
.,
.,
.
I
I
.
!i
~. ~ ad.1ewaetl.e pu-tie,ide
lied.. 41...d;..ueat wd. tm Gtri tee!. oz-
... -:--,....
FIGURE VII-5.
PROPOSED REVIEW PROCEDURE FOR PESTICIDES, ASSUMING
THE Nlll.L H'/PllTHESIS THAT THE PESTICIDE WILL NOT
V10LA:rE GROUND-WATER CR'ITERIA OR STANllARIlS.
"",,,,,',",
83
Chapter vm
CONCLUSIONS AND RECOMMENDATIONS
Ground-water Contamination ill SoIlthold
Ground water in Southold is an
essential resource in need of protection
and reclamation from contamination by
nitrates, pesticides, and organic
chemicals from residential, agricultural,
and other sources. Nitrate and aldicarb
contamination are widespread on the
North Fork, and other pesticides and
organic compounds have also been
detected in some of the Town's wells.
Restoration of the aquifer depends on
protection of the quality of ground-water
recharge since this recharge water will
gradually "flush out" and replace the
water that is in the aquifer now. Long
term protection of Southold's aquifer will
require controlling a large range of
contaminants including nitrate,
pesticides, and the many organic
compounds used by industry, commerce,
and residential households.
Nitrates
Nitrate contamination of ground
water comes from two major sources: (1)
residential development, including septic
systems and lawn fertilizers, and (2)
fertilization of agricultural crops. In the
case of residential development, nitrate
control involves minimizing the use of
lawn fertilizers and keeping housing
densities low enough to spread out the
impacts of lawns and septic systems. As
shown in Figure m-3, simulated average
nitrate recharge. concentrations for
Southold vary from less than two to 10
mg/l as housing densities range from one-
half to four houses per acre and as lawn
fertilization rates range from zero to 3 lb
N/1000 sq. ft.
Consideration is being given in
Southold to clustering of residential
developments in order to preserve open
space and valuable agricultural land. If
housing is allowed to be clustered, then
the resulting open space should be
reserved for unfertilized vegetation or
other uses which would provide the
highest quality recharge water. Housing
and agriculture are both intensive uses
contributing nitrate and other
contaminants to Southold's ground water.
Lower density housing would be a more
compatible use with most forms of
agriculture than would high-density
clustered developments.
When housing is clustered, the
remainder of the acreage within the
development site should be reserved for
unfertilized woodland in order to minimize
its contribution of contaminants to the
ground water. Lands that previously have
been cleared for agriculture or other
purposes can be revegetated using plants
suitable to the local climateological and
environmental conditions. In clustered
developments, this revegetation should be
the responsibility of the developer.
Cooperative Extension, the Soil
Conservation Service, and the Nonpoint
Source Handbook in preparation by the
Long Island Regional Planning Board
(URPB, 1983) can provide guidelines for
revegetation of cleared areas using low
maintenance varieties suitable for the
climate and soils in Southold.
Farm land in Southold is a valuable
resource which forms a basis for the
.Town's economy and rural character. In
order to make farming more compatible
with ground-water quality, efforts have
focused in . recent years on devising
fertilization schemes which will maintain
optimum crop yields while reducing
leaching losses to ground water.
Research in the 1970's on Long Island
'potato farming showed that fertilization
rates at that time were generally higher
than needed, resulting in excessive losses
to ground water. Farmers subsequently
have cut down on their fertilizer use, so
leaching losses also have been reduced.
Field studies and the computer
simulations presented in this report show
150 lb Nt A to be a good average rate for
potatoes, with needs differing slightly
between varieties. Splitting the
application so that some of the fertilizer
is applied six to eight weeks after
planting generally results in lower
leaching losses and higher uptake by the
potato plants than if all is applied at the
time of planting. Other crops have not
been researched as thoroughly but will
need to be as they become more
widespread in Southold.
Pesticides
Pesticides in the past have not been
adequately regulated for protection of
ground water on Long Island. Now that
aldicarb, carbofuran, and several other
pes,ticides have been deteded in mlUlY
Long Island wells, much more careful
attention is being devoted to assessment
of the leaching potential of proposed
chemicals. The pesticide review and
registration process has become so
cumbersome and expensive, however, that
chemical companies are reluctant to
develop new products unless they will
have a very large market. Development
,of chemicals specific to the Colorado
potato beetle and useful in Long Island's
Integrated Pest Management (!PM)
programs therefore would probably not be
given a high priority because of the high
expense for a relatively limited' market.
What is needed is an effective technique
for screening potential pesticides so that
those with very low potential for Ij!aching
'to ground water can proceed more quickly
through the registration process, and
'those for which the environmental effects
are less clear would receive more detailed
study and review.
84
Research and education are being
carried out on ways of reducing the
dependency of both farmers and
homeowners on chemical pesticides. This
is an important goal everywhere, but
particularly on Long Island, where these
chemicals can easily become serious
ground-water contaminants. Increased
emphasis needs to be given to developing
means such as biological controls and
cultural practices which can reduce pest
pressures without impairing environ-
mental quality.
cnpmc Chemicals
Synthetic organic compounds have a
large and ever-growing list of uses in
industrial, commercial, and household
products. Some of these compounds are
highly toxic, and the long-term effects of
ingesting low levels are unknown.
Discovery of these chemicals in ground
water is of particular concern because
their sources are so diverse and
widespread ,that detection and control are
difficult problems. The Suffolk County
ban on organic septic tank and cesspool
cleaners is a step' in the right direction
for controlling these products. More
study is needed on the amounts and types
of compounds used in residential,
commercial, and industrial operations and
on their potential for leaching to ground
water. Disposal of hazardous chemicals,
including empty containers, also is a
diverse and difficult problem, but one of
pressing urgency for ground-water
protection.
A study of existing data on ground-
water contamination by organic chemicals
on Long Island showed the percentage of
wells affected to be proportional to
housing density in four residential
communities (Figure m-9). Maintaining
low housing densities is one step the Town
of Southold could take to limit the
potential for organic chemical
contamination from household products
and from the associated commercial
services that would accompany increases
in housing and population.
RecommendatioDs for Action
Ground-water protection in Southold
will require responsible land use planning
as well as reduced dependency of farmers
and homeowners on fertilizers, pesticides,
and various other organic chemical
products. Large scale educational efforts
are needed to inform the public of the
link between chemical use and
contamination of the underlying aquifer
and to present alternative methods for
fertilization and for pest and disease
control. The following specific actions
would help to minimize future
contamination of Southold's ground water.
A. LaDd Use pl..-g
1. All1'icultural Land Preservation.
One of the major issues facing the Town
is how to preserve the valuable
agricultural lands that form a basis for
the area's economy and scenic rural
character. One important step is to
establish a program for preservation of
prime agricultural lands. Another is to
continue striving for agricultural
practices that produce high quality
ground-water recharge, as discussed in
the All1'icultural Mana~ement and
Research sections below.
Z. Housin~ Development. Another
major land use issue in Southold is housing
development: where it should be located
and in what densities. One potential
ground-water problem caused by housing
is nitrate contamination of recharge from
septic systems and lawn fertilizers. In
order, to plan residential ,development
compatible with ground-water quality, the
Town should choose a planning standard
for nitrate based on the New York State
drinking water standard of 10 mg/l. For
example, if the Town decides that
individual water samples should comply
with the 10 mg/l standard 90 percent of
the time, then a 6 mg/l guideline would be
chosen for planning purposes.
85
One or fewer houses per acre would
meet this guideline at lawn fertilization
rates up to 3 lb N/I000 sq. ft. At lower
lawn fertilization rates, other densities
would also be acceptable, as shown in
Table m-4. If the Town decided to plan
for compliance with the 10 mg/l standard
99 rather than 90 percent of the time,
then I-acre zoning would be acceptable
only if homeowners refrained from using
any lawn fertilizers. Otherwise, lower
density housing would be necessary (Table
m-4). * Lot sizes in clustered
developments should be required to
conform to these same criteria.
Land use planning based on nitrogen
loadings will not necessarily provide
adequate protection from contamination
of the ground water by organic chemicals.
Use of these chemicals is so diverse and
widespread that sufficient data are not
available for devising loading rates
associated with different housing
densi ties similar to those for nitrogen. In
general, however, limiting residential
development to the lowest feasible
density would minimize the number of
potential sources of organic contaminants
from houses and their support services.
3. Ground-Water Man~ement
Plan. Southold Town should develop a
ground-water management plan that
would deal with two basic problems: (1)
the control of pollution sources in order
to prevent the discharge of contaminants
into groundwater; and (Z) the management
of ground-water which is already
contaminated. The plan should locate
critical recharge areas, identify major
point and nonpoint sources of pollution,
and locate areas with sufficient high
quality water to meet existing and
projected future needs.
Southold should adopt land use
ordinances aimed at protection of
* These conclusions are based on the lawn sizes listed in Table IT-Z and on
the assumption that 50% of the grass clippings are removed from the
lawns and used in ways not contributing to nitrate leaching.
designated watershed areas. These
ordinances might include any or all of the
following provisions:
- provide for miuntaining
open space
- restrict clearing of
natural vegetation
- restrict amount of turf
(and other ornamental
vegetation requiring
fertilization) associated
with residential,
commercial and
industrial development
- regulate fertilizer and
pesticide use
- restrict density of
residential development
- prohibit stockpiling of
any farm animal waste
- regulate
h..",U,i"g,
huardous
(including
industrial
certain
products, etc.)
the storage,
and use of
materials
pesticides,
solvents,
household
- prohibit operation or
location of any refuse
disposal area.
B. AlZ1'icultural Management
1. Fertilization. The fertilization
of potatoes should be limited to 150 to
175 Ib N/A/yr depending on variety. This
total rate of application should be split so
that a portion is applied at planting and
the remainder is applied approximately at
the two to eight inch stage of growth,
when the plants are growing rapidly and
have a better chance of taking up the
nitrogen before it is leached. Vegetable
fertilization practices also should be
designed to maximize plant use efficiency
and minimize loss of nitrate to ground
water.
66
Z. Alternative Croppinll: Systems.
Southold farmers should give
consideration to crop diversification and
crop rotations. These practices will
reduce the need for pesticides by reducing
insect populations and by slowing the
insects' development of resistance to
pesticides (Wright et al., 1983). With the
propel' choice of alternate crops, farm
income levels can be maintained (Lazarus
and White, 198Z).
3. Education. Cooperative
Extension should continue and expand
their efforts to inform the agricultural
community of new and improved
management and cultural practices.
Specifically, educational materials and
programs should stress the following:
a. Recommend fertiliza-
tion of potatoes at 150 to 175
Ib NI A/yr, depending on
variety, with specific rates
given for each variety
whenever possible. Promote
vegetable fertilization
practices which will minimize
leaching of nitrate to ground
water.
b. Encourage potato
farmers to split the fertilizer
application, as specified above
(see Fertilization).
c. Emphasize the
benefits of crop diversification
and crop rotation as means of
reducing pest pressure,
lowering pesticide use (and
assocaited costs), and
rejuvenating soils.
d. Demonstrate cultural
and biological methods of pest
and disease control, and
encourage their widespread use
wherever feasible.
As new guidelines are developed for
all crops (see Research below),
educational materials should be made
available and plots established to
demonstrate the new techniques.
C. Residential and Commercial
Land Manllj;!ement
1. Lawn Fertilization. Low
maintenance turf varieties should be used
for residential and commercial lawns,
thus reducing the need for fertilization.
For existing lawns which are not of a low
maintenance variety, fertilization rates
should not exceed Z lb/N/lOOO sq. ft./yr.
Grass clippings should generally not be
removed, but should remain on the lawns
to serve as a slow-release source of
nitrogen fertilizer. If grass clippings are
removed, they should be utilized as mulch
or compost and reapplied to lawn or
garden areas in order to reduce the need
for commercial fertilizers.
Z. Chemical Use and Disposal.
The use of chemical pesticides and
herbicides should be minimized, with
emphasis given to altemative (non-
chemical) means of combating common
pests and diseases. Disposal of
potentially hazardous materials such as
paint thinners, used motor oil, cleaning
solvents, etc., should be accomplished in
such a way that they do not present a
threat to ground water. Disposal of such
materials into cesspool systems or
directly onto the ground are not
acceptable methods, since they will result
in ground-water contamination.
3. Education. The public
awareness of the link between chemical
use and ground-water contamination must
be heightened. Various public agencies,
including Suffolk County Cooperative
Extension (S.C.C.E.), Suffolk County
Department of Health Services
(S.C.D.H.S.), New York State Department
of Environmental Conservation (N.Y.S.
D.E.C.), and the Town of Southold should
prepare and distribute educational
materials which indicate the threat to
ground water (and ultimately to drinking
water) presented by fertilizers, pesticide!!
and other organic chemicals, 'and which
encourage minimal use of all such
67
substances. Specifically, Cooperative
Extension should recommend keeping lawn
fertilization rates below Z lb N/lOOO sq.
ft./yr., leaving grass clippings on the
lawns, and using low maintenance turf
varieties on all new lawn areas. Public
education also should address proper
means of disposing of chemicals
commonly used in residences and
commercial establishments.
It is imperative that the public be
made aware of the serious threat to
ground-water quality posed by many
common household chemicals. A
substantial educational effort will be
necessary to reduce public reliance on
chemicals and should be stressed in all
pertinent publications, news releases,
workshops, etc., produced by S.C.C.E.,
S.C.D.H.S., N.Y.S.D.E.C. and the Town of
Southold.
D. Research
1. ARJ'icultural Practices. The
Long Island Horticultural Research
Laboratory (L.LH.R.L.) should expand and
emphasize its research into and
demonstrations of techniques for reducing
agricultural pesticide and fertilizer use.
a. The Integrated Pest
Management Program and
associated development of
biological and cultural
practices for pest control
should receive top priority in
work by the L.I.H.R.L.
b. Nitrogen fertilization
rates specific for Long Island
conditions should be developed
for all crops to maximize
nitrogen use efficiency in order
to minimize nitrate leaching to
ground water.
c. Monitoring of ground
water for currently used
pesticides and experimental
compounds should be continued
and expanded.
d. Techniques should be
developed to increase the
feasibility of crop rotations and
alternative crops. Research
should include economic
evaluations of labor and
equipment needs as well as
marketing potential.
z. Orll:anic Contaminants. In an
area with septic systems and highly
permeable soils, leaching of household
products containing toxic organic
compounds is a concern. Surveys on the
types and amounts of these products in
industrial, commercial, and household use
would provide a start in determining their
loading rates to ground water. Monitoring
for these chemicals by the Suffolk County
Department of Health Services should be
continued and expanded to provide an
early warning of contamination problems.
3. Aldicarb Simulation. Another
area where more research is needed is in
predicting the timing of aldicarb
contamination at individual wells in
Southold. Cornell's computer model in its
present form can trace the timing and
aerial extent of aldicarb movement
through the aquifer but is not designed to
accurately predict when individual wells
will be affected. This refinement of the
model would be useful in designing
monitoring and water treatment programs
because it would identify the areas where
contamination would be expected to be
most severe at any particular point in
time.
4. Pesticide Screenmll:. A
mathematical model based on existing
field and laboratory data should be
developed for utilization by regulatory
agencies (USEPA and NYSDEC) in
screening pesticides. Such a screening
would indicate where additional field and
laboratory r\,search are required, prior to
'the registration of pesticides for use on
Long Island.
66
E. Rell:ulation and Enforcement
1. Turf Control. The Town of
Southold should consider the adoption of a
turf control ordinance, to limit the
amount of t~f associated with future
residential and commercial development.
Limitations could take the form of
maximum turf area per home or maximum
percentage of each lot, and
encouragement of low maintenance
practices.
z. Pesticide Screening. The U.S.
Environmental Protection Agency, N. Y .S.
Department of Environmental
Conservation, and Suffolk County
Department of Health Services should
carefully screen any proposed agricultural
chemicals to identify their potential for
leaching to ground water under conditions
typical of Long Island. Continued
research and field monitoring could then
focus primarily on those chemicals
identified to be potential ground-water
problems, and other chemicals with a
lower risk could be moved more quickly
through the registration process.
3. CODSUlDer Product Bans. The
Suffolk County ban on septic system
cleaners should be strictly enforced
because these products add organic
pollutants to the ground-water. If other
industrial or household products are
identified as ground-water contaminants,
prohibition of their use should also be
considered at the County level.
4. Interagency Coordination. The
effectiveness of existing surveillance and
enforcement personnel should be
enhanced through improved information
exchange. The NYSDEC and SCDHS
should jointly prepare information
handbooks or pamphlets explaining the
proper storage, handling, and disposal of
hazardous materials. This informational
material should be distributed to the town
building department, town fire inspectors, ,
local fire departments, and other agencies,
whose routine inspections or approval
activities might uncover or prevent
improper use or disposal of hazardous
materials. Similar information on the
household use of hazardous m.aterials
89
should be prepared and disseminated to
the general public.
70
Chapter IX
. ~j
71
POSTSCRIPT
In many parts of the cOWltry, ground
water is taken for granted and assumed to
be invulnerable from contamination by
human activities. On Long Island, in
contrast, discovery of pesticides, synthetic
organic compounds, nitrate, and other
pollutants in the aquifers supplying the
area's sole source of drinking water has
raised ground-water quality to an issue of
urgent concern. As a result, much
attention has focused on means of
providing potable water to meet existing
and future needs. A more difficult, but
equally urgent problem is how to protect
the quality of water recharging the
aquifers since it is this recharge water
which will replenish and restore the
contaminated supplies.
The work presented in this report
was designed to provide information useful
in making land use and management
decisions consistent with protection of
recharge quality in Southold.
Recommendations were made concerning
land use planning, residential development,
agricultural management, public
education, research, and regulations that
would help to restore and protect the
area's ground-water quality. For Southold
this is an important time for water quality
pl"nn;T1g; the Town currently is revising
its land use master plan, and the County
recently has completed an assessment of
water supply options to meet existing and
future needs. The opportunity is ripe for
developing a Town ground-water
management plan to incorporate recharge
quality as an integral consideration when
land use or management decisions are
made.
The ground-water evaluations and
recommendations presented in this report
are intended both to assist Southold in
managing its grOWld-water resources and
to provide an example to other
communities of how grOWld-water
considerations can be integrated into land
use planning and management processes.
72
REFERENCES
:Baier, J.H., and S.F. Robbins. 198Z.
Report on the OccurreIlce and
Movement of Allricultura1
Chemicals in Groundwater: North
Fork of Suffolk County. Suffolk
County Department of Health
Services, Bureau of Water
Resources.
Baier, J.H., and K.A. Rykbost. 1976. The
Contribution of Fertilizer to ti}e
Groundwater on Lon,. Island. Paper
presented at the Third National
Groundwater Quality Symposium,
September 15-17, 1976.
Bond, M.C. 1947.
Agriculture and
Department of
Economics, A.E. 634.
State College of
Cornell University,
York.
Suffolk County
Land Use.
Agricultural
New York
Agriculture,
Ithaca, New
Chapman, R.A., and C.M. Ceile. 198Z.
Observations on the Influence of
Water and Soil pH on the Persistence
of Insecticides. J. Environ. Sci.
Health B17(5):487-504.
Chu, e.c., and G.W. Selleck. 1977. A
Survey of Commercial Potato
Fertilization Practices on L.I.,
1975-1977. Suffolk County
Agricultural News, Vol. LXI,
October 1977.
Cooperative Extension Association of
Suffolk County. 1981. Home
Horticultural Facts: Lawn
Fertilization. Riverhead, New
York.
Hansen, J.L. and M.H. Spiegel. 1983.
Lon,. Term Hydrolvsis Studies of
Aldicarb Sulfoxide and Aldicarb
Sulfone. Union Carbide Corp.,
Unpublished Report.
Hansen, J.L., R.R Romine and M.H.
Spiegel. 198Z. Hydrolysis studies of
aldicarb, aldicarb sulfoxide and
aldicarb sulfone. Environmental
Toxicology and Chemistry Z:147-
153.
Intera Environmental Consultants, Inc.
1980. Mathematical Simulation of
Aldlcarb Behavior on Lon,. Island:
Unsaturated Flow and Ground-Water
Transport. Houston, Texas.
Kain, D.P. and T.S. Steenhuis. 1983.
Adsorption Partition Coefficients
a9lid Deli!;l'adation Rate Constants and
Half-Lifes of Selected Pesticides
Compiled from the Literature.
Unpublished Manuscript. Cornell
University, Ithaca, New York.
Kossack, R.S., and G.W. Selleck. 1979.
Potato Yields, Fertilizer Use and
Water Pollution on L.L Suffolk
County Agricultural News, Vol.
Lxm, March 1979.
Lazarus, S.S., and G.B. White. 1983. The
Economic Potential of c-;OP
Rotations in Lon,. Island Potato
Production. Department of
Agricultural Economics, Cornell
University, Ithaca, New York.
Lemley, A.T. 1983. Unpublished Results.
Department of Design and
Environmental Analysis, Cornell
University, Ithaca, N.Y.
Long Island Regional Planning Board.
1983. 208 Areawide Implementation
Plan - Nonpoint Source Handbook.
In press, Hauppauge, N.Y.
Meisinger, J.J. 1976. Nitro2en
Application Rate Consistent With
Environmental Constraints for
Potatoes on Lon2 Island. Search
Agriculture, VoL 6, No.7. Cornell
University Agricultural Experiment
Station, Ithaca, New York.
National Research Council.
Drinkinll: Water and
National Academy of
Washington, D.C.
1977.
Health.
Sciences.
Pacenka, S. and K.S. Porter. 1981.
Preliminary Re2ional Assessment of
the Environmental Fate of the
Potato Pesticide, Aldicarb, Eastern
Lon2 Island, New York. Center for
Environmental Research, Cornell
University, Ithaca, New York.
Pike, J., S. Goldfarb, and K.S. Porter.
1980. 1980 Survey of Turf
Man~ement Practices in Nassau
and Suffolk Counties, L.L Center
for I!l:nvironmental Research,
Cornell University, Ithaca, New
York.
Porter, K.S. 1982. Groundwater
Information: Allocation and Data
Needs. Center for Environmental
Research, Cornell University,
Ithaca, New York.
Porter, K.S. and N. Beyer. 1977. Report
on Aldicarb. Suffolk County
Cooperative Extension Association,
Riverhead, New York.
Rykbost, K.A., P.A. Schippers, C. Chu,
G.W. Selleck, D.R. Bouldin, J.L.
Ozbun, G. Rathbun, and R.S.
Kossack. 1979. Fertilization of
Potatoes as a Source of Ground
Water Contamination. Appendix 1,
197_ Annual Report of the Long
Island Horticultural Research
Laboratory, Riverhead, New York.
73
Rykbost, K.A., P.A. Schippers, R.S.
Kossack, G.W. Selleck, C.C. Chu,
and D. Bouldin. 1979. Studies in
Fertility and Nitrate Pollution in
Potatoes and Turf on Lon2 Island.
Long Island Horticultural Research
Laboratory, Riverhead, New York.
Selleck, G.W., R.S. Kossack, C.C. Chu,
and K.A. Rykbost. 1980. Studies on
Fertility and Nitrate Pollution in
Turf on LOn2 Island. Long Island
Horticultural Research Laboratory,
Riverhead, N.Y.
Snow, J.T. 1976. The Influence of
Nitrate Rate and Application
Frequency and CliPpin2 Removal on
Nitro2en Accumulation in a
Kentucky B1uel!1'ass Turf. M.S.
Thesis, Cornell University, Ithaca,
New York.
Snyder, D.P. 1982. Cost of Production:
Update for 1981. A.E. Res. 82-20.
Department of Agricultural
Economics, Cornell University,
Ithaca, New York.
Snyder, D.P. 1977. Cost of Production:
Update for 1976. A.E. Res. 77-11.
Department of Agricultural
Economics, Cornell University,
Ithaca, New York.
Tingey, W. 1982. Report presented to
the Colle2e of Life Sciences and
AlZriculture. November 1982.
Cornell University, Ithaca, New
York.
Underwood, F.L. 1933. Costs and
Returns in Producin2 Potatoes in
New York in 1929. Bulletin of the
Cornell University Agricultural
Experiment Station.
U.S. Department of Agriculture. 1954.
Potato Production in the
Northeastern and North Central
States. Farmers' Bulletin No. 1958.
Wilkinson, C.F., J.G. Babish, A. T. Lemley,
and D.M. Soderland. 1983. A
Toxicoloaical Evaluation of Aldicarb
and its Metabolites in Relation to
the Potential Human Health Impact
of Aldicarb Residues in Lonll: Island
Ground Water. Institute for
Comparative and Environmental
Toxicology, Cornell University,
Ithaca, New York.
74
Wright, R.J., R. Loria, J.B. Sieczka, and
D.O. Moyer. 1983. Final Report of
the 198Z LOnll: Island Potato
Intell:rated Pest Manal!:ement Plot
Proll:ram. V.C. Mimeo Z87.
Department of Vegetable Crops.
L.L Horticultural Research
Laboratory, Riverhead, New York.
A-1
AppeDdix A
Potato Pest Management aD Lcmg T,I,"""
. Potatoes have been a major crop on
Long Island for the past 100 years, and the
monoculture nature of the potato farming
has led to problems both for pest control
and for ground-water quality. Pest
populations have built up, requiring large
doses of pesticides, which in turn have led
to loss of effectiven~ss of various
chemicals because of development of
resistant . populations. When aldicarb
(brand name Temil<) was used from 1975 to
1979 on Long Island, it proved to be highly
effective in contr:llling the Colorado
potato beetle and nematode populations.
It had to be banned, however, because it
readily leached through the sandy, acidic
soils and was found in ground water in
concentrations far exceeding the 7 ppb
New York State drinking water guideUne.
Since aldicarb became unavailable, Long
Island growers have increased both the
number of pesticide applica,tions and the
total amounts applied, resulting in higher
costs but not necessarily comparable crop
protection.
There is now a critical need to
develop effective techniques to control
pests if potato farmers are to sustain
adequate production and remain in
business. At the same time, I further
serious contamination of ground water
used for drinking water by new application
of pesticides is unacceptable to all
residents of the North Fork. Given this
double constraint, the need to control
pests, and the need to, protect ground
water quality, Cornell University and its
Long Island Horticultural Research
Laboratory have instituted a vigorous
program of research to discover new
methods of pest controls for Long Island
potato farmers. This section briefly
highlights some of this work. For more
detail, the reader is referred to reports
I
prepared by staff of the Long Island
Horticultural Research Laboratory.
Two overall types of methods for
managing potato pests can be
distinguished:
A. Direct pest control
techniques for use in potato
production.
B. Alternate
systems.
cropping
The work now being pursued is
evaluating both conventional and
innovative approaches to combating the
pests in both types of methods.
A. Direct Pest Control Techniques
Marketable yields of potatoes on
Long Island can be severely limited by the
following pests:
. Colorado potato beetle
. Golden and meadow
nematodes
. Potato scab
. Weeds
Other pests, such as aphids, can also
cause serious damage if uncontrolled, but
there are effective control practices
available to farmers.
1. Colorado Potato Beetle
The Colorado potato beetle on Long
, Island has developed into a voracious pest
capable of rapidly becoming resistant to
pesticides used against it. Since the
development of resistance may be in part
directly related to the degree of exposure
the beetle has to a pesticide, one way of
delaying resistance would be to reduce the
frequency and amount of use of particular
pesticides. Staff at the Long Island
Horticultural Research Laboratory are
formulating action thresholds for the
beetle below which damage caused by the
insect may be tolerated and spraying is
thereby unnecessary. Initial work with
farmers has been encouraging and suggests
that a reduction in the use of pesticides is
a practical option in some circumstances
(Wright et aL, 1983).
Cultural practices which do not
depend on pesticides for reducing the
population of the Colorado potato beetle
are also being evaluated. For example,
earlier applications of chemicals intended
to kill the potato vines prior to harvest
could beneficially reduce the food
available to the beetles.
Biological controls of the beetle are
also being studied although these options
are unlikely to become available in the
near future. One promising natural
control is that achieved by a fungus called
Beauveria bassiana. The fungus is
completely safe in environmental and
ecological respects and may be eUective
in at least suppressing the numbers of
beetles that may develop each season.
Another promising but long term biological
option is to develop potato plants which
are resistant to the beetle. Some wild
species of potatoes, which are known to be
resistant, are now being interbred with
domestic varieties. One type of resistance
is provided by the presence of substances
called glycoalkaloids in the potato plant.
Unfortunately, the substances lack
discrimination in which parts of the potato
plant they are found, and hence occur in
the tubers as well as the leaves.
Another defensive mechanism found
in some potato species are adhesive or
sticky hairs. When touched by an insect,
these hairs exude a viscous gum which
sticks to the insect and rapidly hardens
(Tingey, 1982). The insect is eventually
immobilized and dies. Affected insects
,
A-2
sometimes assume a "Charlie Chaplin"
appearance with large gum boots on each
leg (Figure A-1). The sticky hairs are
effective against aphids as well as the
Colorado potato beetle.
1"1...._ Pot8to lHf
FIGURE A-I. AN APHID ON THE LEAF OF A HYBRID
POTATO PLANT THAT PRODUCES A
STICKY BLACK GUM, TRAPPING INSECTS
AND CAUSING THEM TO STARVE TO DEATH.
2. Nematodes
The pesticides now available for
nematode control (nematicides) are of
limited and variable effectiveness. A
more immediately promising option is to
introduce potato varieties which are
resistant to the nematode. However, the
existing resistant varieties may lack the
qualities or characteristics which would
lead to their adoption by Long Island
farmers. Short-term options to control
the golden nematode are therefore
seriously limited.
3. Potato Scab
Potato Scab (Figure A-2) is
especially significant for farmers on Long
Island because the most effective method
of control is for the farmers to maintain a
low pH on their potato fields.
Unfortunately, crops which might
. otherwise be used in a rotation with the
potatoes become impractical possibilities
because they would be, to some degree,
incompatible with the high acidity in the
soil. Dealing with potato scab on Long
FIGURE A-2. A POTATO SHOWING THE EFFECTS OF THE
POTATO SCAB DISEASE.
Island has, therefore, fostered the
monocultural practices which in tum make
it more difficult to deal with potato pests
such as the Colorado potato beetle and
the golden nematode. Currently, work at
the Long Island Horticultural Research
Laboratory is investigating the biology and
ecology of scab. Scab resistant potato
varieties are available, but these are not
considered to be lUI commercially
attractive as potatoes now com,monly
grown on Long Island.
4. Weeds
Weeds which invade potato fields
compete with the crop for space, nutrients
and water. The weeds may also harbor
pests as well as hindering the efficiency
with which the potato tubers can be
harvested. Weed control is therefore a
serious economic issue for the potato
farmer. Two primary weeds are barnyard
grass and nutsedge (Figures A-3 and A-4).
Bindweed (Figure A-5) has shown an
increasing tendency to mitrate from its
traditional home, the roadside, and is
impacting potato production in some
areas. There currently are no' practical
controls for these weed species, and an
overall control strategy needs to be
developed incorporating information on
their biology and ecology as well as
whatever chemical and cultural practices
are available.
Jr-3
~,,",,
'\\
FIGURE A-3. BARNYARD GRASS (ECHINOCHLOA CRUS-
GALLI) A COI1I1ON WEED IN POTATO
FIELDS IN SOUTHOLD. N.Y.
FIGURE A-q. NIJTSEDGE (CVPERUS ROTUDUS). A
. COMMON WEED 'IN POTATO FIELDS IN
SOUTHOLD, N. Y I
\
FIGURE A-5. BINDWEED (CONVOLVULUS ARVENSIS).
A WEED COMMONLY FOUND ALONG ROAD-
SIDES WHICH ALSO INVADES POTATO
FIELDS IN SOUTHOLD. N.Y.
B. Cl'<>P Rotations and Altemative
C1'OPS
Crop rotation can break the life
cycles of some pests, thereby decreasing
the need for pesticides and slowing the
development of insect resistance to each
chemical. Rotation also helps to maintain
soil vitality because each crop depletes or
restores soil nutrients in differing ways.
For many years, potato farmers
have followed a seasonal rotation by
sowing rye after the potatoes have been-
harvested. The rye is plowed under prior
to planting the potato seeds in the
following spring and adds to the soil
organic matter. To the extent the rye
increases soil biological activity in the
soil, it may assist in the retention and
biodegradation of pesticides. The rye
cover also decreases wind erosion during
the winter months.
1. Annual Crop Rotations
However, for reasons
discussed, annual rotations
already
are not
A-4
followed to an extent which could break
the pattem of monocultural production.
Recent work carried out at Comell and at
the Long Island Horticultural Research
Laboratory suggests that crop rotation
might nevertheless be beneficial. For
example, Wright et a1. (1983) report that
on three farms out of four, potatoes grown
on fields previously used for another crop
had lower populations of the Colorado
potato beetle than did fields on which no
rotation took place. On the fourth farm,
the overall number of the Colorado potato
beetle were so low that differences
between the rotated and non-rotated fields
were immaterial. A preliminary
economic evaluation carried out by
Lazarus and White (1983) showed that
rotation of some potato fields with
cauliflower would result in decreased
pesticide use ,and greater income than if
all fields were in continuous potato
production. Most other rotations
decreased net returns to some extent, so
crops would need to be carefully chosen to
maintain farm income levels. The
adaptability of potato farmers is, however,
restrained by the high degree of
specialization they have achieved. The
investment in equipment and facilities
such as storage sheds represent a major
commitment of capital that has limited
transferability to other crops.
Z. HousinlZ As An Altemative
An obviously profitable altemative
"crop" for many former potato farmers on
Long Island has been housing. From an
environmental, viewpoint, the replacement
of farms with houses, highways and other
land uses may be substantially more
threatening than the farms they replace.
Unfortunately, other crops have been less
successful than residential developments
in supplanting the potato. Clearly this is a
'consequence of the economic forces
involved. However, no economic analysis
has been undertaken recently which
systematically evaluates the costs and
benefits of these major options now
confronting farmers. Over the past few
years there have been some encoUl'aging
economic tendencies: The farmland
preservation program has provided
economic incentives to continue farming,
increasing numbers of roadside farm
stands have given farmers a direct and
very profitable means of marketing a wide
variety of produce, and new crops such as
grapes few wine production are proving to
A-5
be economically viable.
It therefore appears timely to
undertake a macro-economic analysis of
the cunent patterns of farm production
and options. Through such an analysis it
might be possible to fUl'ther develop and
support viable cropping alternatives in the
fu tUl'e.
B-1
Table B~ 1
Summary of Assumptions Relating to Each Land Use Type
Land Use CatQ()ry Assumption Value Information Source
RI. Residential .. Population density Z.5 penana/acre Population demity
(o-Z dwel1lngol_,,") b. Percentage of land estimates "ere hued on the
UV&clUlt 50% 1980 Ceuua, _bieb reported
c. Percentage of land Z.54 penou/bouH for the
as turf Z5% Town of SoutbolcL
.. Percentage of land aa
impenious surface Z5%
All land caver pvcentaglll
caIculatioftli were bued on
meUU1'emltDu from local low-
altitude air photos.
RZ. Residential .. Population density 7.4 persons! acre
(Z-4 dwelling.t/acre) b. Percentage of land
.. vasant 17%
c. Percentage of land
.. tUl'f 45%
.. Percentage of land at
impervious surface 38%
Auumptiou applying .. Pel' capita sewqe Porter and others, 1978
to aU reaidential nitrogeD generated 10lbol_yr
b. Pel' capita ..wage NYS Deputment of Health
flow lenuated by 40 gaUonolpenoa/ 1969; Porter and others,
pel'MlUl ""ed by day 1978
oD-lite system..
AI. Apiwlturet PotatDell .. Depth of root 1I01le Z4 inches Suffolk County Cooperative
(eropluulln potato b. MuimWD plant Ditrogren ExteuiOD
productioa.) cont_t if all growth 180 lb N/A
cODdlttGDI are optimal
c. Percerttqe of bUYested
plant btom.... Ilitrogea 30%
removed from field.
.. Percentage of buyested
plant btomau altrogen 70%
removed from field
e. Amount of inorganic
Ilitrogn fertilizer 1751b/Atyr
applied
r. Irrigation water amount 3 iDcbes/yr.
AZ. AgricultW'e: Mixed .. Depth of root zone Z4 inches (Suffolk County Cooperative
Vegetables (Land b. Maximum plant nitrogen 134 Ib N/A Extenaion and Jim Pike,
de'VOted to truck crops conteDt if all growth South Fork mixed vegetable
such as tomatoes, condttioDllue optimal fumer.
peppers, cucumbera,ettc. c. Percentage of harvested
A winter grain cover plant biomua nitrogen 66%
crop is auumed.) retUl'Jled to soil
.. Percentage of harvested
plant biomaa nitrogen 34%
removed from field
e. Amount of iDorganic
nitrogen fertilizer 118 Ib NI A/yr
applied
r. Irrigation water amount
,'.
B-2
Table B-1 (CONTINUED)
Summary of Assumptions Relating to Each Land Use Type
Land UN Cateao" Auumption Value Information Source
A3. AIrlcu1t....' VlDey""'" .. Depth of root 'IOone 47 incbes Suffolk County Cooperative
(LaDd In table or b. Maximum plant nitrogen ~teusion
wine grape produc:tion) if aU growth conditions
are optimal Z11b N/A
c. Percent... of bane.ted
plant blom... lIitrogen
returned to solI 80%
"- Percent... of harvested
plant biomass aitrogen
removed from field ZO%
e. lDorganic aitrogen
fertili'lOer applied 30 IbN/A
f. Irrigation water amount o iDcbet/yr.
A4. Agriculture: OreharU .. Depth of root 'IOone 47 incbes Suffolk County Cooperative
(Land in tree fruit b. Maximum plant uitrogea
productioa) coatent if all growth
COftditions are optimal 536 Ib NIA
c. Percentage of banested
plut biomaa nitrogen
returned. to soU 10%
"- Percent... of bane.ted.
plut biom... nitrogen
removed froID field 90%
e. lDorganic nitrogen
fertUber ~pUed 100 1b NI A/yr
f. Irrigation water amount Z.O lncbn/yr
A5. Aaricu1tunc Nuneri.. .. Depth of root zone 1.4 inch.. Suffolk County Cooperative
(LaIId dPoted. to pro- b. Madmum plant nitrogen Exteaaion
ductiOll of ornamental content, if all growth
trees and llluuba) conditions are optimal 455 lb/aere
Co Percent.. of harv..ted
plant btomua nitrogen
returned to soU lm
d. Percentage of harvested
plant biomass nitrogen
removed from field 100%
e. Number of harvests per
ye.. Z
f. Percentage of total plant
biom... nitrogen banested
at each b......e.t ZO%
g. Total nitrogen fertilizer
applied Z50 Ib N/A/yr
b. Irrigation water amount 3 incbea/yr
A6. Agriculture: 1st Year .. Depth of root sone 8inchea Suffolk COWlty Cooperative
Sod (Land UHd for b. Maximum plant uptake Extenaion
commercial sod fanning, mtrogen if all growth
with crop planted in conditions are optimal Z13lb NIA Dr. Arthur Bing, Long
September) c. Total nitrogen fertilt'lOer blaDd Horticultural ReNllI'Ch
applied 186 Ib NI A/yr Laboratory
A1. Agriculture: Zad Year .. Depth of root :zone 8 inch.. Suffolk County Cooperati'9'e
Sod (Land ued for b. Maximum plant uptake Extension
commercial sod farming, nitrogen If all growtb
with crop hargested in conditions are optimal 1.73 lb N/A 01'. Arthur Bing, Long
October of the 1.nd year) Co Percentage of har....ted bland Horticultural Reaearcb
plant biom... nitrogen Laboratory
returned to soil 0%
"- Percentage of harvested
plant biomau nitrogen
removed from field 100%
e. Total nitrogen fertilizer
applied 2.89 lb NI A/yr
B-3
Tabl. B-1 (CONTINUED)
Summary of Assumptions Relating to Each Land Use Type
Land U.., CateRPrv Auumption Value IDformation Source
A8. . Agriculture: Grain a. Depth of root zone 2.4 inches Estimated from data from
(fle14a being vested b. Mutmum plant uptake eutem Lona Island
for a year following nitrogen if all growth experiments (Meiaina:er, 1976).
potato or other conditions are optimal 179 Ib NIA
vegetable production) Co Percentage of harvested. Suffolk COUIlty Cooperative
(980) plant biom... ExteuiOD
nit~n retum to soU 10",,"
d. Percentage of huvelted
plant blom... nitrogen
remo...ed from field 0%
e. Inorpnic nitrogen
f~rtUizeJ' applied ....
A9. Agriculture: Cole Crops a. Depth of root zone OZ4 inchea Suffolk County Cooperative
(land devoted. to crops 1>. Mwmum plant biom... EzteDaion
such aa cauliflower, nitrogen if all growth
cabbap, ud. bnauel coDditiona are optimal 1341b NIA
sprout&. A winter CGver c. Pel'(!eDtage of harvested
C1'Op of grain i. plant blom... nitrogen
....mod. returned to soU 66%
d. Pel'ClhItagel of harvested.
plant blom... nitrogen
.eat to muk.et 34%
.. Ino:ft~c' nttl'Ogea
fert Uaer 138 Ib NI AI."
01. Other. Golf Courses Percentage of Land as Turf: 85% Dr. A. Mutin Petro"ic.
FaIrways 60% Cornell Uni"ersity Dept.
Roughs ZO% of Floriculture and
Greens 3% Ornamental Horticulture
T... Z%
Percent of land as V.CUlt 10%
Percent of land as impervious 5%
Fertilizer Nitrogen appUed
Fairways 98 Ib NIA
Roughs & groun~ 55 Ib N/A
Greens ZOO Ib NIA
T... ZOO lb N/A
0.... Other: Horse Puture. a. Depth of root zone 8 incbe. Suffolk County Cooperative
(LaDd used for .ruing b. Maximum plant uptake ExtensioD
of ho...... with a nitrogen if aU growth Z73 Ib N/A
deDaityof 1 hone/acre conditions are optimal
p'uins 8 montlu/yeu Co Percentage of harvested
plant biom... nitrogen
returned to lIOil 0"-
d. Percentage of !:lanested
plant biom... nitrogen
removed from field 100%
.. Inorganic nitrogen
fertilizer applied ....
I. MUlure nitrogen applied 400 lb NI A/yr
",-...,,,;.
8-4
Covel' Type
1. Turf
2.. ImpemOlU
SUI'face
Table B-Z SUmmarv of A8sumvtlolll Relatinll to Residential Land Cover Tvves*
Auum'Ptions
(a) half of the initial content of animal wute is lost in the
atmosphere.
(h) all pet .ute auumed. to be deposited on turf. Pet
population hued. OIl hume population' and doss ad. eab per
penon for Loq 1llaDd. Pet ...te procluction is about
5.3 pams N pel' day per dog and. 4 grams N per day per cat
(c) Turfp'usleaf deuity is ummed to.,.ary during the year,
peaking in late ~ring aad summer and. being leat in winter.
(d) Depth of root zone is ZO em
(e) Turf mowings U'e UlIUmed to bi-weekly during the summer
and to each remove 10 percent of the biomass
(f) 50 percent of hanested. plant biom... nitrogen is returned
to soU and. 50 percent is remo.,.ed.
(g) Bued on a lawn fetUizer use auney of Long Island, 1076
lawraa in Southolci recei.,.e about 54 kg of total nitrogen
per hectare per year (I.llb N/IOOO ftZ). Half the
total is uaumed to be in ala. releue compounds, and
the other half in fat rele.. compounds
(h) Lawn miaation is esUmated to be about 8 em (3.1
inches) annually
(a) There is auumed to be no root zone
(h) All water is -..umed to run off onto adjacent pervious
......
. A.uumpticma relatiq to agricultural and other CQ't'er types are co.,..red in Table A-I.
~
Porter (1975) and Lauer and. otbers
(1976)
Rates bued on clata from Loehr
(19704) and Porter and. others
(1978)
Surny of Lona IslaDd turf manage-
ment, summer 1978 (Porter and
others, 1980)
Porter and others (1978)
Table 8-3
Rates and Timings of morganlc Fertilizer (Kg N/hal
Southold Demonstration Site
lot lnd Golf Courses
Beginning Year Year HorR Mixed Rough.
Dayol Time n,,( Potatoes Grain Cole Crops Orcbards Vineyards Sod Sod Nurseries Pastures Vegetables Fairways G......s. Greens Tees
Time Step ~ .!!!al!!!! ("",ha) !YI!!!! !YI!!!! .!W!!!l .!W!!!l .!W!!!l jWJ!!! .!W!!!l l!!Bl!!!! (ko/hol .!W!!!l J!!siJ!!l. .!W!!!l ~
Jan. 1 1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Jan. 13 l 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.., 0.0
Jan. l5 3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Feb. 6 . 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Feb. 18 5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mar. l 6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mar. 14 7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mar. l6 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Apr. 7 9 0.0 19l.5 0.0 0.0 0.0 0.0 0.0 0.0 61.7 0.0 0.0 0.0 0.0 0.0 0.0
Apr. 19 10 0.0 0.0 0.0 0.0 110.0 33.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
May 1 11 19.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 M.' 0.0 0.0 0.0
May 13 Il 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 99.0 0.0 0.0 48.8 48.8 III
,
May l5 13 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Ul
June 6 1. 0.0 0.0 0.0 110.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 36.6 36.6
June 18 15 0.0 0.0 0.0 0.0 0.0 0.0 0.0 64.9 0.0 0.0 33.0 0.0 0.0 0.0 0.0
June 30 16 0.0 0.0 0.0 44.0 0.0 0.0 0.0 0.0 61.7 0.0 0.0 0.0 0.0 0.0 0.0
July Il 17 0.0 0.0 0.0 0.0 0.0 0.0 0.0 . 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
July l4 18 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Aug. 5 19 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Aug. 17 lO 0.0 0.0 0.0 0.0 0.0 0.0 58.1 73.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Aug. 19 II Z9.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Sept. 10 ZZ 0.0 0.0 0.0 0.0 0.0 0.0 64.9 64.9 0.0 0.0 0.0 48.8 61.0 48.8 48.8
Sept. Zl Z3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Oct. 4 M 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Oct. 16 Z5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 101.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Oct. l8 Z6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Nov. 9 'Z7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 61.7 0.0 0.0 0.0 0.0 0.0 0.0
Nov. II Z8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Dec. 3 Z9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Dec. 15 30 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
1~360 SUM 58.6 19l.5 0.0 IS4.0 110.0 33.0 Ill.O l30.8 185.1 0.0 13l.0 73.l 61.0 134.l. 134.l
Table B-4
Rates and Timings of Organic or Slow-Release Fertilizers (Kg N/ha)
Southold Demonstration Site
lot '.d Horse Gal( Courses
Beginning Ye.. Ye.. (Manure) Mixed Rough.
Day of Time nul Potatoes Grain Cole Crops Orchards Vineyards Sod Sod Nurseries Pastures Vegetables Fairways G""""" Greens Tees
Time Step lliP. .!!!Bl!!!l J!!8l!!!l (kolha) J!!8l!!!l J!!8l!!!l J!!8l!!!l J!!8l!!!l J!!8l!!!l (kolhal J!!8l!!!l J!!8l!!!l J!!8l!!!l J!!8l!!!l J!!8l!!!l (kolh~
Jae. I I 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Jae. n . 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Jae. Z5 3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Feb. 6 . 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Feb. 18 5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mar. Z 6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
M... I' 7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Mar. 2.6 8 0,.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Apr. 7 9 0.0 14.0. 0.0 0.0 0.0 0.0 0.0 0.0 30.0 ZZ.O 0.0 0.0 0.0 0.0 0.0
Apr. 19 10 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
May I 11 2.9.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
May. 13 1Z 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 5... 0.0 0.0 0.0 0.0
May 2.5 n 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
June 6 I' 0.0 0.0 0.0 9.1. 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 U.. 0.0 0.0 0.0 ID
JUDe 18 IS 0.0 0.0 0.0 0.0 0.0 0.0 0.0 43.3 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0 d.
JUDe 30 16 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 30.0 2.2..0 0.0 0.0 0.0 0.0 0.0
July 12. J7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 ZZ.O 0.0 0.0 0.0 36.6 36.6
July 24 18 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 22..0 0.0 0.0 0.0 0.0 0.0
Aug. 5 19 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 22..0 0.0 0.0 0.0 0.0 0.0
Aug. 17 ZO 0.0 0.0 0.0 0.0 0.0 0.0 38.7 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Aug. 2.9 ZI 29.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Sept. 10 ZZ 0.0 0.0 0.0 0.0 0.0 0.0 43.3 43.3 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Sept. 2.2. Z3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Oct. 4 U 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2.0 0.0 0.0 0.0 0.0 0.0
Oct. 16 Z5 0.0' 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Oct. Z8 Z6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Nov. 9 Z7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 30.0 2.2..0 0.0 0.0 0.0 0.0 0.0
Nov. ZI Z8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 4.8.8 48.8
Dec. 3 Z9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Dec. 15 30 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
1~360 SUM 58.6 14..0 0.0 9.1 0.0 0.0 82..0 86.6 90.0 44.0.0 5.1 2.4..4 0.0 85.4 85.4
.These numbers refer to the winter grain cover crop wbicb is plowed. under.
Table 8-5
Irrigation Amounts llDd Timings
Southold Demonstration Site
I.t Znd Golf Counes
Beginning Year Year Mixed Rough &:
Day of TIme Turf Potatoes Grain Cole Crops Orehuda YineylUda .... .... Nuneries PastUl'eS Yegetables Fairways G....... Greens Tees
Time Step ~ (em) (em) (em) (em) (em) JEmL JEmL JEmL (em) (em) (em) (em) (em) (em) (em)
Jan. I I ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Jan. I] Z ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Jan. Z5 3 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Feb. 6 . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Feb. 18 S ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Mar. Z 6 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Mar. 14 7 ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
Mar. z6 8 ... ... ... ... ... ... ... ... ... ... ... ... ... 0.0 0.0
Apr. 7 9 ..0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Apr. 19 I. ... ..0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.. 0.0 0.0 0.0 0.0 ...
lllay 1 11 ..0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.. ..0 0.0 0.0 ..0 0..
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C-1
App-ili... C
Turf Nitrogen Simulations
One of the major concerns on Long
Island is the contamination of ground
water due to nitrates and the contribution
that nitrogen fertilizers used on turf adds
to this contamination. The assessment of
nitrogen leaching from turf described in
this report is based on a detailed
simulation of water and nitrogen
movement in the turf root zone using the
W ALRAS root zone nitrogen simulation
model. The model computes the amount
of nitrogen that leaches out of the root
zone and gets into ground water, taking
into account all of the significant
environmental and management factors
such as soil properties, climate,
fertilization timing and rate, pet waste
deposited on turf and irrigation. The
details of the W ALRAS simulation models
can be found in manuals written by the
Center for Environmental Research.
This appendix describes:
(1)
how the model was
calibrated to be
consistent with field
experiments on turf
uptake of nitrogen,
(Z)
a comparison of
simulated nitrogen
leached with observed
nitrogen in ground
water, and
(3) an assessment of the
uncertainty of the
simulation results.
Ca1ilmition
The two most significant fates of
nitrogen in the turf root zone are uptake
by the plants and leaching (gaseous loss
and runoff also remove nitrogen from the
root zone.) Plant uptake by turf has been
extensively measured in field experiments
in a way which allows a direct comparison
with simulated plant uptake. Therefore
we were able to calibrate the plant
uptake simulation using these field results
which were conducted by the Long Island
Horticultural Research Laboratory,
L.LH.R.L. (Selleck et al., 1980).
Between 1974 and 1976' the eight
fertilization treatments described in
Table C-l were tested on experimental
turf plots at the Long Island Horticulutral
Research Laboratory. At the end of the
experimental period the nitrogen content
of the plants was measured. The amount
of nitrogen fertilizer taken up by plants
was determined by subtracting the
nitrogen content of unfertilized turf on
control plots from the nitrogen content of
fertilized turf.
These experimental conditions were
simulated using the W ALRAS model and
the field results and the simulation results
. were compared. Minor adjustments were
made to the parameters which control the
plant uptake simulation to make the
model consistent with this experiment and
with nitrogen uptake results measured on
sod farms as part of the same L.LH.R.L.
study.
Figure C-l shows a comparison of
the simulatea and observed nitrogen
uptake by turf. Line A represents the
amount of nitrogen which would be in the
Plants if their uptake of fertilizer
nitrogen was 100% efficient. Line B
represents the actual amount of fertilizer
nitrogen retained in, the plants. The
simulation results compare well with the
observed results.
C-2
Table C-1. Rates and dates of fertilizer N aplied to turf
(Selleck and others, 1980)
Fertilization
Rate per
Application Total N Total N
Treatment (lb N/1000 sq ft) Dates of Application /3Z mos. /yr
1 0 0 0
2 .260 1974: 5/26,6/24,9/2
9/24,10/9,11/5 .
1975 and 1976: 4/1,4/21
5/7,6/1,9/1,9/21,10/7,
11/1 5.64 1.89
3 1.03 1974: 5/26,9/2
1976 and 1977: 4/1,9/1 6.15 2.05
4 .51 as in 2 (above) 11.28 3.75
5 1.03 1974: 5/26,6/24,9/2
10/9
1975 and 1976: 4/1,9/1 12.3 4.10
6 2.05 1974: 5/26,9/2
1975 and 1976: 4/1,9/1 12.3 4.10
7 1.03 as in 2 (above) 22.55 7.50
8 2.05 as in 5 (above) 24.60 8.2
Comparison with Well Data
In order to test the accuracy of the
simulations for predicting ground
water quality underneath turf, simulation
results were compared with water quality
data from shallow observation wells in
the Twelve Pines subdivision in Medford,
N.Y. (Figure C-2).
The subdivision was constructed on
previously-wooded lands starting in 1970.
Fourteen shallow observations wells were
installed by U.S.G.S. and Suffolk County
in the Spring of 1972. The water table at
that time was about forty feet below the
land surface.
FIGURE C-l. COMPARISON OF FIELD DATA
WITH HAWS SIMULATIONS
OF NITRGGEN UPTAKE BY
TURF.
c
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EXIT 115
C-3
25
0- SIMULATION RESULTS
e- FIELD RESULTS
A
20
B
15
1Ci1
5
o
o
5
10
15
20
25
,... of N!itrog,.n
(I~./_ ft.2/32 /ltOA1the)
.'"
I I $MIGY AR'EA
"..1
e WELL L0CATIIilN>S
..
.
fi\1iIII
~
o
RECH'ARGE B'ASIN,S
lteSI'DENIJ"I AL AR EA>S
WElIilDED loR EAS
VACANT AREAS
..,
Tw.... Pin..
FIGURE C-2. TWELVE PINES STUDY AREA.
C-4
During the 1972 to 1978 period, data
were collected to estimate the amount of
nitrogen added to the soil. Since the area
serviced by collective sewers which
export sewage from the start, sewage was
not a significant source. This allowed for
closer analysis of the nitrogen sources
associated with turf management,
rainfall, and pets. Table C-2 summarizes
the data used in the W AI..RAS simulations.
Turf simulations were combined with
water and nitrogen simulations of
forested land and impervious surface to
calculate the overall nitrogen content of
recharge water. The simulation results
are summarized on Table C-3.
Table C"'Z
Buic Data for the Twelve Pines Subdivision
Value(sl
Remarks""
Parameter
Fraction of area occupied
by turf.
0.50
<1mated by meuure-
ments of low-altitude
aerial photos and at
site.
Fraction of uea
covered by impervious
.....face.
0.16
As abo..e.
Nitrogen concentration
in predpitation.
1 mg/l
Bued on aample. by
Suffolk COUDty Dept. of
En.,.. ControL
Nitrogen concentration
in water supply ..ter
(mea).
2..1 mg/l
Bued on Ample. of tap
water.
Lawn fertilizer
rate.
Z.2. Ibll/lOOO at ft/p
From Porter and othen
(1918). 1916 data.
Pat ...te aitrogen
application rate.
16 'q/ba!yr
Fraction of lawn
cUppiDg. removed.
0.75
1916 hom80WIle1' auney.
Table C.3
Simulated Nitrogen in Recharge-
Twelve Pines Study Area
Nitrogen
Water Nitrogen Concentration
Y!!!: RechU'lled {in} Recbarnd Ub/.ere) (malU
19n 45.7 17.9 1.1
1973 Z8.1 13.3 l.1
1974 18.Z 10.9 l.7
1975 Z8.4 16.5 l.6
1976 15.6 1.l l.O
. Simulations include 'Vacant land and impervious IlUl'face wbich contribute
small amounts of nitrogen as well .. tW'f which i. the main source of nitrogen
in recharge. AU ruJlofr water is usumed to b4I recharged through recharge
basins.
Four of the observation wells were
located in areas which received some
recharge from outside of the study area,
c-s
so data from these wells were not used.
Data from the ten remaining wells
(1,4,5,6,8,9,10,11,13,14) are summarized
in Table C-4 for each year.
Table C-4
Summary of Twelve Pines Well Data
Total Nitro2en Wells 1,4,5,6,8,9,10,11,13,14
~ Number of Samples Mean (ml/:/I) Standard Deviation (m2/1)
197Z 40 1.58 1.14
1973* 8 1.05 0.64
1974 36 1.47 1.34
1975 40 2.17 1.49
1976 30 2.15 1.20
1977 20 2.19 1.36
1978 41 2.55 1.03
* Samples not representative of the year. Data for Mayor June, 1 sample per
well, only.
The time it takes for recharge
water to travel the 40 feet from the
surface to the water table is
approximately 2 years (assuming general
sand and gravel subsurface conditions).
The simulated recharge nitrogen
concentrations should thus be compared
with nitrogen concentrations measured in
wells two years later. Because flow in
the unsaturated zone is variable,
subsurface water mixes and the nitrogen
concentrations observed in wells will
actually represent a mixture of recharge
water from several years. The simulation
results are compared with the field
measurements in Table C-5. The
simulated concentrations correspond
closely to the observed concentrations.
A8Besment of Uncertainty
A sensitivity analysis was conducted
on the turf simulations to determine the
margin of error in the results, caused by
the uncertainty of the accuracy of the
way turf is represented by the model.
The model was constructed by using the
best estimated value for each parameter
in order to accurately represent the
system. For the sensitivity analysis the
parameters were changed to represent the
range of possible impacts that the system
might have on nitrogen concentrations in
recharge. The parameters were varied
systematically to represent the maximum
possible impact that the turf system
would have on ground water nitrate levels
and the minimum possible impact. Table
C-6shows the ranges of parameters that
were used and the simulation results.
.C-6
Table C-5
Comparison of Observed and Simulated Nitrogen Concentrations
in Ground Water, Twelve Pines Subdivision
Year Wells
Sampled
Average Nitrogen
Concentration in
Wells (mlt!l)
1.47
Z.17
Z.15
Z.19
Z.55
(1974)
(1975)
(1976)
(1977)
(1978)
average:
Z.l1
Z.ZZ
The maximum impact simulation
resulted in a nitrogen concentration 10%
greater than the medium impact; the
nitrogen concentration of the minimum
impact simulation was 46% less than the
medium impact. The comparison of
simulated nitrogen concentrations with
Simulated Average
Nitrogen in Recharge
(mg/l)
1.7
Z.1
Z.7
Z.6
Z.O
Year Root Zone
Simulated
(197Z)
(1973)
(1974)
(1975)
(1976)
observed concentrations on Table C-5
showed that in that case the amount that
the simulated concentrations differed
from the observed concentrations was
well within this range. These ranges were
used in computing confidence intervals
for land uses involving turf.
I"su C-6.
Summary of Senutivity An.alysis of the W ALRAS
Root ZODe Water and Nitrogen Simulattona for Turf
For Conditions Representing Southampton, N.Y.
Maximum Impact Medium Impact Minimum Impact
Peameter* aD Gl'OUIld Water on Gl'OWld Water.. on Ground Water
o Depth of root :lODe: 10 em 1.0 em 30 em
(MID) IMID) 111.8 inl
o MuimuID allowable pllLat
nitrogeD content: 15 kg/ha 300 kg/ha 300 kg/ha
(68.2. Ib/acre) (Z 72.. 7 Ibl acre) (2.12.71b/acre)
o Puameter allowing
increued N uptake via
diffusiou:... 0 0 0.5
o Denitrification rate: 0.0003 l/day 0.0005 l/day 0.001 l/da,.
o Fraction of inorganic
fertillzer which is
loet u .. g..: 0.02.5 0.05 0.1
Simulated Nitrogen
Concentration in Recharge
Water: 10.3 mg/l 9.4 mill 5.1 mg/l
. The pU'ameten are described in detail in the WALRAS manual&.
.. The me<Uum impact parameters are the best estimates of these parameters
determined bom literature and the calibration.
... The la:rger this parameter the faatet' the plants will take ,up nitrogen in the
simulations.
0-1
AppendiT D
Potato Nitrogen Simulations
Leaching of agricultural fertilizers
is a major concem on Long Island, and one
of the objectives of this project has been
to evaluate how various management
practices can help to reduce these
fertilizer losses. Since potatoes are the
primary crop in this region, much of the
research at the Long Island Horticultural
Research Laboratory (L.LH.R.L.) has
centered around potato production.
Wherever possible, we have used the
results of such research in setting up and
verifying our W ALRAS potato
simulations.
. Cah"bration of the Potato Model
Between 197Z and 1975, research
was carried out at the L.LH.R.L. on the
effect of rate and timing of fertilizer
nitrogen on yield and nitrogen recovery in
Katahdin potatoes.
Plots received 80 or 160 lb N/Ac
either at planting or in split applications
(Table D-1).
Table D-1
Fertilization Rates and Timings for L.LH.R.L.
Experiments on Katahdin Potatoes,
197Z-1975
Fertilization during plant stage
(lb N/A)
Treatment
Fertilization
at planting
(lb NI A)
4-6"
high
Total
quantity
of nitrogen
(lb NI A)
emergence
early
bloom
1 80 0 0 0
2 40 20 20 0
3 40 0 20 20
4 160 0 0 0
5 80 40 40 0
6 0 0 40 40
80
80
80
160
160
160
Results from these field
experiments were used for calibration of
the W ALRAS root zone model for
nitrogen uptake by potato plants. Most
fertilizer nitrogen is either taken up by
plants or leached to ground water, with
much lower losses to runoff and
volatilization. Detailed field data are not
. available on nitrate leaching below potato
fields, so data on plant uptake of nitrogen
were used instead for the model
calibration. Adjustments were made to
the model parameters controlling uptake
of nitrogen by the potato plants in order
to make the model fit as closely as
possible to the field data.
140
~
..
...
..
~
.=
o
..
"
..
&. 60
-
o
..
c
!40
c
o
(.)
Z
20
o
1
2
3
4
Treatment Number
D-2
Table D-Z compares the tuber
nitrogen contents from these field
experiments with those from our
W ALRAS simulations over the period
from 1972 to 1975, and Figure 0-1 shows
a comparison of the results for t'hese four
years averaged together. On average
over the four years, the W ALRAS results
for tuber nitrogen were slightly low for
the three treatments with 80 pounds of
fertilizer nitrogen and slightly high for
those with 160 pounds of fertilizer
nitrogen (Figure 0-1). In all cases,
however, the average simulated results
were well within the range' of field results
for the four years measured.
KEY
X := WAlRAS rnults,
weraged 1872-1975
O. Fiekl ,..ull..
averaged 1972-1975
I. R_of..........
fl.1d ,.autt.. 1972-
1875
5
6
FIGURE D-l.' COMPARISON OF WALRAS SIMULATION RESULTS WITH FIELD
MEASUREMENTS OF THE NITROGEN CONTENT OF POTATO TUBERS,
THE FIELD EXPERIMENTS WERE CARRIED OUT BY THE LONG
ISLAND HORTICULTURAL RESEARCH LABORATDRY.
Assessment of Uncertainty
The W ALRAS potato model includes
many parameters in its simulation of'
plant uptake of nitrogen, and values for
these parameters have been estimated
from field data wherever possible. In
,order to determine how variability or
uncertainty in these values affects the
simulation results, we conducted a
sensitivity analysis by systematically
varying plant uptake parameters in the
25
D~3
potato model. The results are shown in
Figure D-Z. The error bars around each
point in this figure show how the range of
uncertainty in the plant uptake equations
affects the predictions of nitrate
concentrations in recharge water. The
shaded points represent the conditions
which best fit field observations, as
previously discussed, and these values
were used for the potato simulations in
this report.
20
-
~ Carver and ptymouth Sands
~ ,.
&
;
'5
.!
oS
i 10
I
i
5 RI.,...,,_ and Haven Sot..
150
150
Nltr~.n Fertilizer AppUed (Ib/ae,.)
170
150
180
200
F!GURE D-2. SfNSITIVITY ANALYSIS FOR THE WALRAS POTATO SIMULATIONS.
THE ERROR BARS AROUND EACH POINT SHOW THE VARIATIONS
IN SIMULATION RESULTS CAUSED BY VARYING PLANT UPTAKE
P~RAMETERS IN TIlE MODEL.
D-4
Table D-Z
ComparilOlI of Field and Simulation (W ALRASI Results for Nitrogen
Content of Harvested Potatoes
Treatments are as Defined in Table 0-1
Tuber N Content (lb HI A)
191Z 1973 197. 1975
TreatlDeIlt Field W ALRAS Field. WALRAS Field W ALRAS Field W ALRAS
. .!!!!!!!!. .B!!!!!!. l!!!!!!!!. ~ ~ a_to ~ ~
52 64 73 70 107 81 91 71
Z 57 73 81 77 125 83 77 76
3 59 7. 83 77 115 84 8. 78
4 52 92 90 104 133 In 113 105
5 66 107 9' 116 137 US 107 115
6 74 111 88 118 145 i26 119 118
AHl'age 197Z-1975
Field W ALRAS
.!!!!!!!. .B!!!!!!.
81 n
85 77
85 78
97 105
101 116
106 118
E-l
Glossary and Abbreviatious
Appendix D
Glouary
Aquilino. A geological layer which is
saturated and can yield significant
quantities of water to wells and
springs.
Clustered Development. Grouping of
houses into a higher than otherwise
permissable density, leaving the
remainder of the site in open space.
Concentration. The weight of a substance
that is dissolved in a given volume
of water; milligrams per liter (mg/l
for short) is the unit used here,
which refers to milligrams of the
substance per liter of water.
ContamiDaDt. A substance which makes
water less fit or unfit for human use
or consumption and which is not
present naturally.
EvapotraDspiration. Processes which
convert liquid water in the soil and
on the surface into vapor; includes
direct evaporation and transpiration
by plants.
Flow Path. The path along which ground
water flows, usually under steady-
state conditions.
Ground water.
geologic
surface;
table.
Water saturating a
stratum beneath land
all water below the water
Integrated Pest M;magement ttPM). The
use of chemical, cultural, genetic,
and biological pest control methods,
in ways designed to have minimal
effect on nontarget organisms and
the environment.
r.ee..1m,g. The process by which moving
water removes a substance from a
zone of soil; chemicals may be
leached from the soil and carried
downward by recharge water.
Nitrate. A chemical compound containing
one nitrogen atom and three oxygen
atoms; nitrate in the diet reduces
the ability of the blood to carry
oxygen, especially in very young
infants.
Permeability. The property or capacity
of a porous rock, sediment, or soil
for transmitting a fluid; a measure
of the relative ease of fluid flow.
Rec:harge. The process by which water is
added to ground-water storage,
usually from the surface.
Recharge area. The location at which
water can enter an aquifer directly
or indirectly; generally an area
consisting of a permeable soil zone
and underlying rock material "that
allows precipitation or surface water
to reach the water table.
Root zone. The upper portion of the
unsaturated zone, inside which plants
and atmospheric processes influence
water flow strongly and in which
biological processes that decompose
contaminants into basic chemicals
(such as water and carbon dioxide)
are the greatest.
Saturated zone. The zone below the
water table; all pore spaces are
filled with water.
Simulation. Estimation of movement of
water and dissolved chemicals to the
ground water, based on site-specific
calculations of processes including
precipitation, evaporation, plant
uptake, runoff, and leaching.
Synthetic organic chemicals. Chemical
compounds not normally found in
nature that are synthesized by
humans; include many plastics,
herbicides, pesticides, and solvents;
this group includes most of the worst
toxic and hazardous materials to
which people are exposed.
Uusaturated zone. Zone between the land
surface and the water table, inside
which some of the pore spaces are
filled with air rather than water.
WALRAS. The Water and Land Resource
Analysis System, a system developed
at Comell University for simulation
of movement of water and dissolved
chemicals to and through the ground
water.
E-2
Water budget. An accounting of all of the
inflows, outflows, and changes in
storage of water within specific
boundaries and over a specific time
interval, such as a year.
Water table. Top of the saturated zone.
Abbreviations
lb Nt Alyr. Pounds of nitrogen per acre
per year.
mg/l. Milligrams per liter, referring to
the number of milligrams of a
substance per liter of water. A
milligram is one. thousandth of. a
gram.
ugfJ.. Micrograms per liter. A microgram
is one-thousandth of a milligram.