United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas, NV 89193-3478
Research and Development
EPA/620/SR-94/014 June 1994
Project Summary
Environmental Monitoring and
Assessment Program:
Agroecosystem Pilot Field
Program Report- 1992
C. Lee Campbell, Jeff M. Bay, Anne S. Hellkamp, George R. Hess, Michael J.
Munster, Karen E. Nauman, Deborah A. Neher, Gail L. Olsen, Steven L. Peck,
Brian A. Schumacher, Kurex Sidik, Mark B. Tooley, and David W. Turner
The Agroecosystem Resource Group
(ARG) of the Environmental Monitoring
and Assessment Program (EMAP) has
developed a five-year strategy for the
development, evaluation, and imple-
mentation of a suite of indicators for
monitoring the status and trends of
agroecosystem condition on a regional
and national basis. The five-year pe-
riod includes time to test concepts re-
lating to design, indicators, quality as-
surance, logistics, information manage-
ment, data analysis, assessment, and
reporting at the pilot and demonstra-
tion program stages. A primary em-
phasis is on the development of close
working relations between personnel
from the U.S. Environmental Protection
Agency (EPA), the U.S. Department of
Agriculture's (USDA) Agricultural Re-
search Service (ARS) and National Ag-
ricultural Statistics Service (NASS) and
the ARG. The 1992 Pilot Field Program
in North Carolina evaluated all aspects
of the monitoring program for a se-
lected suite of indicators. The Pilot was
conducted over an area large enough
to provide reliable answers to ques-
tions concerning the operation of the
monitoring program but small enough
to be physically and fiscally manage-
able. Results will be used to plan for a
regional demonstration project and to
address specific concerns of applying
the program indicators in a different
geographic area of the country. In ad-
dition, results will assist the ARG in
establishing an acceptable sampling
design, set of core indicators, logis-
tics, quality assurance and information
management protocols, and an assess-
ment framework for use in monitoring
the status, trends, and condition of the
nation's agroecological resources.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Las Vegas, NV, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
ordering information at back).
ti
Introduction
In 1992 a Pilot Field Program was con-
ducted in North Carolina by members of
the Environmental Monitoring and Assess-
ment Program's (EMAP) Agroecosystem
Resource Group (ARG). EMAP originated
within the Office of Research and Devel-
opment (ORD) of the U.S. Environmental
Protection Agency (EPA) and is now an
interagency, interdisciplinary initiative to
monitor the condition of the nation's eco-
logical resources. The U.S. Department of
Agriculture's (USDA) Agricultural Research
Service (ARS) provides technical leader-
ship for the Agroecosystem component,
one of eight resource categories within
EMAP. The ARG cooperated with the
USDA's National Agricultural Statistics
Service (NASS) in the development and
data collection aspects of the 1992 Pilot.
The three principal agencies cooperated
Printed on Recycled Paper
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in the Pilot as the first developmental step
toward the implementation of a plan for
monitoring the ecological condition of
agroocosystems in the United States.
The mission of the ARG is to develop and
implement a program that will, in the long
term, monitor and assess the condition and
extent of the nation's agroecosystems from
an ecological perspective through an inter-
agency process. The specific objectives of
the ARG parallel the overall EMAP objec-
tives. When fully implemented the pro-
gram will
Estimate the status, trends, and
changes in selected indicators of the
condition of the nation's agroecological
resources on a regional basis with
known confidence.
Estimate the geographic coverage and
extent of the nation's agroecological
resources with known confidence.
Seek associations between selected
Indicators of natural and anthropo-
genic stresses and indicators of the
condition of agroecological resources.
Provide annual statistical summaries
and periodic assessment of the
nation's agroecological resources.
An agroecosystem is a dynamic asso-
ciation of crops, pasture, livestock, other
plants and animals, atmosphere, soils, and
water. The agroecosystem includes not
only the field or pasture but also the asso-
ciated border areas such as windbreaks,
fence rows, drtchbanks, and farm ponds.
The agroecosystem boundary depends on,
and varies with, the process being consid-
ered. Agroecosystems interact with larger
landscapes, which include uncultivated
land, drainage networks, human commu-
nities, and wildlife. The landscape is the
area that directly affects the ecology of
the agroecosystems and is directly affected
by agroecosystem processes. The land-
scape boundary also depends on, and
varies with, the process being considered.
The sustainability of agroecosystems is
of primary importance to the people of the
United States and the world. Although
there are several aspects of sustainability,
the ARG is interested in the ecological
sustainability of agroecosystems. An
agroecosystem is ecologically sustainable
ii it maintains or enhances its own long-
term productivity and biodiversity, the
biodiversity of surrounding ecosystems,
and the quality of air, water, and soil.
The EMAP-Agroecosystems monitoring
effort is based upon assessment ques-
tions related to three societal values. The
three societal values for agroecosystems
are the components of ecological
sustainability: quality of air, water, and
soil; productivity; and biodiversity.
The ARG developed a multiyear pro-
gram to establish the regional and na-
tional implementation of a suite of indica-
tors for monitoring the condition of
agroecosystems. The first stage of the
program (1990) encompassed the initial
evaluation of (1) statistical designs; (2)
existing monitoring programs (i. e., NASS,
Soil Conservation Service, and Economic
Research Service); (3) assessment ques-
tions and associated indicators (for their
availability, validity, variability, and cost);
(4) data management and analysis tech-
niques; and (5) methods of reporting on
indicators. During 1990, a national moni-
toring strategy was developed on the ba-
sis of these evaluations. In the second
stage of the program (1991) in-depth ex-
aminations were conducted of several ar-
eas critical to the planning and implemen-
tation of the Pilot Field Programs: (1) sta-
tistical design options; (2) measurements
associated with specific indicators and as-
sessment questions; (3) sampling proto-
cols; (4) cooperation with NASS; (5) logis-
tics; (6) quality assurance; and (7) infor-
mation management. The 1992 Pilot in
North Carolina, conducted in cooperation
with USDA NASS, tested aspects of the
monitoring program with a limited suite of
indicators. Results of the 1992 Pilot will
be used to develop (based upon availabil-
ity of funds) additional pilots and regional
demonstrations that eventually will lead to
national implementation.
Purpose and Objectives
The 1992 Pilot was designed to evalu-
ate aspects of the EMAP Agroecosystem
monitoring program critical to the imple-
mentation of a regional and national pro-
gram. It was designed to address these
program aspects over an area large
enough to provide reliable answers to
questions concerning the operation of the
monitoring program but small enough to
be physically and fiscally manageable.
There were three major objectives of
the 1992 Pilot:
1. Compare the relative efficiency, in
terms of cost and precision, of two sam-
pling frames.
2. Evaluate an initial suite of indicators
to
Assess the ability of each indica-
tor to address the assessment
questions of interest;
Establish an initial range of values
for each indicator across the di-
verse physiographic regions of
North Carolina;
Assess spatial variability of indi-
cator values within and among
sample units;
Identify the usefulness and sensi-
tivity of each indicator in deter-
mining ecological condition; and
Determine cost-effectiveness for
each indicator.
3. Develop and refine plans for
Sampling
Logistics
Quality assurance
Data analysis, summarization, and
reporting
Information management
Ecological health indices and their
interpretation
The 1992 Pilot was also conducted to
establish a cooperative, working relation-
ship with NASS at both the state and
national level. NASS has a well estab-
lished nationwide network of enumerators
experienced in conducting national sur-
veys. Also, growers throughout the United
States are familiar with NASS personnel
and have confidence in NASS because of
the NASS data confidentiality require-
ments.
North Carolina was selected for the 1992
Pilot because
1. The physiographic diversity of the
state is representative of the
ecoregions of the southeastern re-
gion of the United States.
2. NASS is organized by state. Limit-
ing the Pilot to one state simplified
problem resolution.
3. Most of the ARG staff is located in
Raleigh, NC, which facilitated lo-
gistic activities.
Design and Statistical
Considerations
The ARG considered two sampling plans
in the 1992 Pilot, each of which used the
NASS Area Frame segments as the basic
sampling units. The two plans differ in the
way the segments to be used for indicator
sampling are selected. The Pilot study
evaluated the results of a sampling strat-
egy based on using the EMAP Hexagon
Design to select the NASS segment to
the Rotational Panel Plan that uses a sub-
set of segments from the NASS June Enu-
rnerative Survey (JES). Fifty-one segments
distributed over 49 counties were used
from the EMAP Hexagon Design and 65
segments distributed over 55 counties
were used from the Rotational Panel Plan.
Only fields planted with annually harvested
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herbaceous crops were eligible for selec-
tion as a sample unit. For each design,
crops in each field in each segment were
identified during the NASS JES. An aver-
age of three fields were selected at ran-
dom from each of the 65 segments for
195 sample units for the Rotational Panel
Plan and from each of the 51 segments
for 153 sample units for the Hexagon De-
sign. Ten sample units from the Rota-
tional Panel and 17 from the Hexagon
Design were not sampled due to farmer
.refusal, inaccessibility of the field, the field
not being in the designated resource class,
or enumerator error.
Ponds and wells for sampling were iden-
tified from lists developed by NASS from
the North Carolina JES. Initially, 51 ponds
and 81 wells were identified from the Ro-
tational Panel Design only. Because of
refusals and other factors identified previ-
ously, 40 ponds and 61 wells were actu-
ally sampled.
Data were assembled from three
sources: the JES, the EMAP Fall Survey
questionnaire, and samples of soil and
water collected by NASS enumerators. All
questionnaire data were compiled by
NASS and transmitted to the ARG. Soil
samples were submitted to one commer-
cial laboratory for analysis of physical and
chemical parameters and to another com-
mercial laboratory for nematode identifi-
cation and enumeration. All water samples
were analyzed by personnel and contrac-
tors from EPA's Environmental Research
Laboratory in Athens, GA.
The primary statistical tool used to sum-
marize indicator data from the 1992 Pilot
is the cumulative distribution function
(CDF). Ninety percent confidence bands
were added to each CDF in order to indi-
cate the precision of the estimated CDF.
The population reported is typically the
area of land in North Carolina, the Pied-
mont region of North Carolina, or the
Coastal Plain region of North Carolina cul-
tivated with annually harvested herbaceous
crops.
Results
Results are presented for the indicator
categories land use, crop productivity, soil
quality (physical and chemical), soil biotic
diversity, water quality, and agricultural
chemical use. In the full report, results for
each indicator are presented in a question
and answer format similar to what might
be used in the future for annual statistical
summaries. In a few cases, boundaries
for acceptable (nominal), marginal, and
unacceptable, (subnominal) conditions are
presented. In most cases, however, con-
dition boundaries are not proposed and
will be developed for future reports. The
following summarizes the results.
Extent and Geographic
Distribution of Annually
Harvested Herbaceous Crops
Annually harvested herbaceous crops
are planted on about 1.68 million hectares
and cover some 13% of the total land
area in North Carolina. Crops included in
the Pilot were barley, corn, cotton, hay,
oats, peanuts, potatoes, rye, soybeans,
sweet potatoes, sorghum, sunflowers, to-
bacco, vegetables (all), and winter wheat.
Information on extent and distribution of
these crops was obtained by analyzing
data from the complete NASS JES. Ques-
tions answered include (1) how much land
is cropped?; (2) how diverse are the state's
croplands?; (3) do these cropped areas
tend to be dominated by a single crop?;
(4) how large are the crop fields?; and (5)
how do different size fields contribute to
the total area of annually harvested her-
baceous cropland? For example, North
Carolina fields tend to be small, with a
median field size of just over two hectares
regardless of the type of landscape. Addi-
tionally, half of the total area of annually
harvested herbaceous cropland occurs in
fields smaller than 6.09 hectares.
Crop Productivity
Two indices of crop productivity are pre-
sented: nitrogen use efficiency and stan-
dardized (observed/expected) yield. Ques-
tions answered are (1) how efficiently is
nitrogen being used to produce annually
harvested herbaceous crop? and (2) is
crop productivity meeting expectations
based on soil and climate?
Nitrogen use efficiency is the ratio of
the amount of nitrogen applied to a field
to the harvested yield from that field. Thus,
the smaller the number the greater the
nitrogen use efficiency. Information for cal-
culating this index was obtained from the
EMAP Fall Survey questionnaire. Fifty per-
cent of the land area in North Carolina
cropped to corn, wheat, soybean, and cot-
ton had nitrogen use efficiencies of 0.029,
0.035, 0.011, and 0.120 or less, respec-
tively. For all seed crops combined, 50%
of the land area planted to these crops in
North Carolina had nitrogen use efficien-
cies of 0.022 or less.
Standardized yield was calculated in re-
lation to an 11 -year reference period in an
initial attempt to answer the question: how
can data from different crops be brought
together in a single productivity index?
The eventual goal is to answer the ques-
tion: is crop productivity meeting expecta-
tions based on soil and climate? If ob-
served and expected yields are the same,
standardized yield has a value of 1.0; if
observed yields are greater than expected,
the index has a value greater than 1.0;
and if observed yields are less than ex-
pected, the index has a value less than
1.0. The median value for all the observed/
expected indices presented is greater than
1.0. This index presented for a single year
has little meaning; however, over the long
term this type of index should reflect
changes or trends in overall crop produc-
tivity.
Soil Quality - Physical and
Chemical
Physical and chemical properties of soils
largely determine and reflect the produc-
tive potential of land. For the 1992 Pilot,
we analyzed composite samples from the
AP horizon for particle size, organic mat-
ter, cation exchange capacity, selected
micro- and macronutrients, and some con-
taminants related to sludge application.
Questions posed include (1) do soils have
acceptable amounts of clay to sustain crop
production?; (2) do the soils have accept-
able levels of organic matter in order to
provide aeration to the roots and retain
nutrients?; (3) do soils have pH levels that
facilitate the availability of essential plant
nutrients?; (4) do the soils have cation
exchange capacities that enable nutrient
storage and supply?; (5) do the soils have
adequate plant available phosphorus to
sustain plant growth?; and (6) do the soils
have lead or cadmium levels that pose
health risks to the ecosystem?
As an example, ranges of 18-35% clay
content and organic matter content of
greater than 1 % are proposed as accept-
able levels to promote growth of crop
plants. Based upon these criteria, the pro-
portion of land cropped with annually har-
vested herbaceous crops that have soils
with acceptable levels of clay and organic
matter for growth of crop plants is 0.36 in
the Piedmont, 0.10 in the Coastal Plain,
and 0.30 for the state as a whole.
Soil Biotic Diversity
Biotic communities in soil are respon-
sible for the decomposition of organic mat-
ter, are involved in many aspects of nutri-
ent cycling, provide mechanisms for the
development of pore spaces within soil,
and interact with plant roots. The status of
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the soil biota is vital to the overall charac-
terization of soil condition or health.
Nematodes may serve as a good indi-
cator of soil condition because they are
diverse in their feeding habits and occur
as central members of the soil food web.
A highly stable or mature community of
nematodes would indicate minimal distur-
bance or contamination of the soil biota.
Questions answered in the Pilot included
(1) what is the degree of stability or matu-
rity in nematode communities in soil? and
(2) what is the degree of diversity of nema-
todo communities in soil?
For land cultivated in annually harvested
herbaceous crops in the Piedmont and
Coastal Plain regions of North Carolina,
only a small proportion of communities of
soil nematodes had a relatively high de-
gree of stability or maturity. The propor-
tion of land area cultivated with annually
harvested herbaceous crops having val-
ues for the maturity index for free-living
nematodes of less than 3.2 on a 1-5 scale
(where 5 is the most mature or stable
community) was estimated to be 0.95. A
higher proportion of larger values (>3.0)
was found for soils in the Piedmont than
in the Coastal Plain region for both free-
living and plant-parasitic nematodes.
Trophic diversity values had a greater
range in the Piedmont than in the Coastal
Plain with higher index values occurring in
the Piedmont.
Water Quality
Water is essential to any agroecosystem,
and it carries materials from the
agroecosystem into the larger landscape.
Ponds and wells were sampled during the
fall sample of the Pilot, and water samples
were analyzed for two types of contami-
nants: nitrates and pesticides. Questions
addressed include (1) what is the distribu-
tion of nitrate concentrations in wells on
farms in North Carolina?; (2) what is the
distribution of nitrate concentrations in farm
ponds in North Carolina?; and (3) how
extensive is pesticide contamination of
farm ponds and wells in North Carolina?
For wells, the EPA maximum contami-
nant level for water is 10 ppm nitrate-N.
From the Pilot data, an estimated 3.5% of
wells had greater than 10 ppm nitrate-N,
and the median concentration was ap-
proximately 1 ppm. The maximum con-
centration detected was 19 ppm nitrate-N.
In farm ponds, concentrations of nitrate-N
were generally less than those found in
wells with a median concentration of 0.2
ppm, A spectrum of 12 insecticides/
nematicides and herbicides was not de-
tected above the one part per billion thresh-
old in any sample fronvwells or ponds.
Agrichemical Use
Fertilizers and pesticides are integral
components in the production of crops in
agroecosystems. Applications of materi-
als in both of these agrichemical catego-
ries can result in both positive and nega-
tive effects on the biological components
of agricultural systems. A preliminary ques-
tion addressed in the Pilot was how much
stress is put on the ecosystems of North
Carolina by applying chemical fertilizers
and pesticides?
Extent of use of agrichemicals may be
one indication of potential stress placed
on agricultural systems. As an example,
extent of use of four materials was con-
sidered: the herbicide atrazine; the bio-
logical control agent Bt or Bacillus
thuringiensis (used against insect pests);
the insecticide/nematicide carbofuran; and
the commercial fertilizer nitrogen. Atrazine,
Bt, carbofuran, and fertilizer nitrogen were
applied at least once to 17.8, 0.8, 2.1, and
75.5% of the land area of annually har-
vested herbaceous crops in North Caro-
lina. Atrazine was applied an average of
1.06 times and fertilizer nitrogen an aver-
age of 1.72 times per year.
Evaluation of Designs,
Indicators, and Activities
Design comparisons were performed
primarily for fall questionnaire and soil
sample data. Only statewide estimates
were used and the comparison was done
both accounting for and ignoring stratifica-
tion by intensity of agricultural use, which
was provided by NASS. The efficiency of
one design relative to another was de-
fined as the ratio of the variances for the
statistic of interest, adjusted for different
sample sizes when necessary. A relative
efficiency greater than one indicates that
the Hexagon Design is more efficient,
whereas a relative efficiency less than one
indicates that the Rotational Panel Design
is more efficient. For eight measures of
soil quality (physical and chemical) and
two measures of crop productivity, ac-
counting for stratification, the Rotational
Panel Design was more efficient in eight
cases and the Hexagon design was more
efficient in two cases. When relative effi-
ciency was calculated with cost included
as a factor, the Rotational Panel Design
was always the more efficient design.
Successes and challenges in indicator
development and evaluation were specific
to the indicator considered. In general,
indicators performed well; however, the
suite of indicators is not yet sufficiently
well developed to fully assess the ecologi-
cal condition of agricultural systems. For
assessing crop productivity, one challenge
is how to successfully bring together dif-
ferent crops into a single, interpretable
productivity index. For assessing soil qual-
ity, the challenge is to develop a single,
interpretable index that incorporates the
key physical, chemical, and biological fac-
tors of soil health. For assessing the ex-
tent and geographic distribution of annu-
ally harvested herbaceous crops, one chal-
lenge is to provide a clear interpretation of
crop diversity or land use diversity indices
that can be calculated. For agrichemical
use, a challenge is how to integrate EMAP-
Agroecosystems data with information al-
ready collected by other federal agencies.
Another challenge for all indicators is to
quantify the frequency and magnitude of
measurement errors.
Activities in all areas of the Pilot were
generally successful. The interactions with
NASS personnel were very successful with
NASS personnel involved in four areas of
the Pilot: (1) collecting data during their
regular JES; (2) drawing the sample of
fields to be visited in the fall; (3) designing
and conducting the fall questionnaire; and
simultaneously (4) collecting fall soil and
water samples. The Pilot was generally a
logistical success. Questionnaire perfor-
mance and survey administration, soil sam-
pling, water sampling, shipping and sample
tracking, laboratory relations, and report-
ing back to respondents generally occurred
in a satisfactory manner. The quality as-
surance (QA) aspects of the Pilot pro-
ceeded in two components as planned.
NASS has a well-established QA program
and EPA personnel performed successful
field audits during data collection and labo-
ratory audits during sample analysis. With
regard to information management, the
primary goalto develop a cooperative,
working relationship with NASSwas
achieved. Extensive discussions within the
ARG and with personnel in partner agen-
cies have been held to review Pilot activi-
ties, and lessons learned will contribute to
the success of future efforts.
Conclusions
The 1992 Pilot in North Carolina pro-
vided an initial test of the concepts relat-
ing to design, sampling, indicator devel-
opment, data analysis, quality assurance,
logistics, and information management. A
preliminary comparison of the efficiency
of two sampling frames or designs was
made. An initial suite of indicators for the
extent and distribution of cropland, crop
productivity, soil quality, water quality, and
agrichemical use was evaluated with re-
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spect to the ability of indicators to address
assessment questions; the spatial vari-
ability of indicator values within and among
sample units; the usefulness of each indi-
cator in determining condition; and the
cost-effectiveness of each indicator. Plans
for sampling; logistics; quality assurance;
data analysis, summarization, and report-
ing; and information management were
made, carried out, and evaluated. The
information obtained from the Pilot will
allow the ARG to continue to evaluate
and develop the program components es-
sential for the eventual implementation of
regional and national monitoring programs
to assess the condition of the Nation's
agricultural systems.
- This research was funded primarily by
the U.S. Environmental Protection Agency
(EPA) through its Office of Research and
Development under Interaqency Agree-
ment Nos. DW12934170 with the U.S. De-
partment of Agriculture, Agricultural Re-
search Service, and DW1293747 with the
USDA National Agricultural Statistics Ser-
vice. It was conducted by our research
partners under the management of the En-
vironmental Monitoring Systems Laboratory,
Las Vegas, in support of the Environmental
Monitoring and Assessment Program.
&U.S. GOVERNMENT PRINTING OFFICE: 1994 - 55O-M7/80270
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C. Lea CampbalUs with the USDA Agricultural Research Service, Raleigh, NC
27606; Jeff M. Bay, Karen £ Nauman, Kurex Sidik, David W. Turner, Anne S.
Hellkamp, George R. Hess, MichaselJ. Munster, Deborah A. Neher, Steven L.
Peck, and Mark B. Tooley are with North Carolina State University, Raleigh,
NC 27695; GailL Olsen is with EG&G Idaho, Inc., Idaho Falls, ID 83415; and
the EPA author, Brian A. Schumacher, is with the Environmental Monitoring
Systems Laboratory, Las Vegas, NV 89193-3478.
Susan E. Franson is the EPA Project Officer (see below).
The complete report, entitled "Environmental Monitoring and Assessment Program:
Agroecosystem Piht Field Program Report - 1992," (Order No. PB94-179 819
Cost: $27.00, subject to change) will be available only from:
National Technical Information Service
528S Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Off her can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Las Vegas, NV 89193-3478
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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