United States
                   Environmental Protection
                   Agency	
National Exposure
Research Laboratory
Las Vegas NV 89193-3478
                   Research and Development
EPA/620/SR-95/004  July 1995
4>EPA       Project Summary

                   Environmental  Monitoring and
                   Assessment  Program
                   Agricultural  Lands  Pilot  Field
                   Program  Report—1993
                     This document provides a compre-
                   hensive report on the EMAP Agricul-
                   tural Lands 1993 Pilot Field Program,
                   which was conducted in Nebraska. Re-
                   sults of the pilot monitoring effort are
                   presented on land use and cover, crop
                   productivity, and soil quality (physical,
                   chemical, and biological). Other aspects
                   of the  pilot study are also addressed
                   including design and sampling, indica-
                   tor evaluations, logistics, quality as-
                   surance and information management.
                     This Project Summary was developed
                   by EPA's National Exposure Research
                   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 Project Report
                   ordering information at back).

                   Introduction
                     The Environmental  Monitoring and As-
                   sessment Program (EMAP) is being de-
                   signed  to help policy makers decide how
                   to allocate limited resources among envi-
                   ronmental problems. Many monitoring ef-
                   forts are site- or problem-specific and do
                   not allow assessment of condition over
                   large regions with statistical confidence.
                   EMAP will track the condition of our envi-
                   ronment on a regional basis.
                     The  mission  of EMAP's Agricultural
                   Lands  Resource Group (ARC) is  to de-
                   velop and implement a program that will,
                   in the long term, monitor and assess the
                   condition and extent of the nation's agri-
                   cultural lands. The specific objectives are
                   to
                        Estimate status and trends in con-
                        dition.
     Estimate geographic coverage and
     extent.
     Seek stressor-condition associa-
     tions.
     Provide summaries and assess-
     ments.
  The ARG conducted its second Pilot
Field Program in Nebraska in 1993. There
were three  major objectives:  (1)  test a
suite of indicators in these categories: land
use and cover, crop productivity, and soil
quality; (2) compare the relative efficiency
of two sampling designs;  (3) develop and
refine  plans for key  components  of the
monitoring program.
  Nebraska was selected primarily be-
cause of the  presence  of both  typical
midwestern intensively cropped lands and
western sparsely cropped lands. Address-
ing ecological condition in widely varying
settings is crucial for developing a suite of
indicators that can be used nationally.
  EMAP uses probability sampling frames
to choose sample sites, allowing statisti-
cally valid statements to be made for a
region. Two different frames were used;
288 sites in Nebraska were  chosen, all
planted to annually harvested herbaceous
crops (AHHCs). After the 1993 fall har-
vest, data were collected on crop  yields,
soil  characteristics, and management. In
addition, data on land use and cover were
provided from the National Agricultural Sta-
tistics Service's June Agricultural Survey.

Land Use and Cover
  AHHCs are planted  on over 7.4 million
ha in Nebraska, covering 37% of the state.
Most are found in the extensively culti-
vated lands in eastern and southern Ne-

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braska; western Nebraska is predominantly
rangeland that is sparsely  cropped. Corn
is the most common crop  (45% of crop-
land); soybeans are the second most com-
mon crop (14%).
  Crop  diversity was measured as  the
number of different crops in a given area
and their relative  abundance. In the  ex-
tensively cropped  lands, one third of the
sample  areas (260 ha  each)  contained
four crops; in  half the areas, a single crop
(usually corn) accounted  for more than
55% of the total cropped  acreage. How
diversity changes  with time will  be  of in-
terest:  decreasing  diversity would signal
increasing vulnerability to  pests and  dis-
eases.
  Approximately  75%  of all fields in
Nebraska's extensively cropped lands are
16  ha or smaller; this  differs from  the
usual impression of Nebraska as a state
covered by large fields. Approximately 35%
of the extensively  cropped  lands are cov-
ered by fields in this size range.
  There are nearly 75,000 farm ponds in
Nebraska,  covering  almost 58,000  ha.
More  than  half are less than  0.3  ha in
area. Water for livestock is  the single larg-
est  use of farm ponds, followed by ero-
sion and flood control.

Crop Productivity
  Is cropland producing the yields we ex-
pect? We calculated the ratio of the yield
reported for each sample field to the county
average yield for that crop over the period
1980-1989  (irrigated  fields compared to
the average for irrigated fields; nonirrigated
compared to   nonirrigated). For the  five
predominant crops, 1993 was slightly bet-
ter than average; soybeans did better than
corn or sorghum.
  Is  cropland  requiring increasing subsi-
dies  of nonrenewable inputs? We exam-
ined nitrogen  use efficiency by calculating
the  quantity of nitrogen applied for each
unit of harvested  material.  Not only soy-
beans (a legume) but also wheat shows
more efficient use of applied nitrogen than
the  predominant crop, corn.
  Are  crops   being  managed for  plant
health? We examined crop rotation in three
ways.
  (1) Rotation plans. We estimate that
nearly half of the AHHC land in Nebraska
is not covered by any planned rotation; of
the land in rotation, half the plans are two
years in  length.  (2)  How long since the
1993 crop was grown in that field? Over
half the AHHC land had the same crop in
1993 as  in  1992, and 72% of the  corn
acreage had been planted to corn in 1992.
This is a substantial  lack of rotation for a
crop that occupies half of the AHHC acres
in  Nebraska. (3) How many  crops were
grown in the past three years? Forty-two
percent of the AHHC land  had the same
crop every  year  out  of three; corn  again
predominated.

Soil Quality
  Surface soil samples were  analyzed for
a set of physical, chemical, and biological
indicators. Median values for clay, organic
carbon, and cation exchange capacity are
lowest in  northwestern and highest in east-
ern Nebraska; median pH values follow
an opposite trend, with the highest in the
northwest.  An  integrated  rating  showed
better quality surface soils  in eastern and
southern  Nebraska than in  the northwest.
This pattern corresponds to  the  trend in
land use, with most cultivated land in the
eastern part of the state.
  A maturity index  for free-living nema-
todes, which reflects  the degree of stabil-
ity of soil biota, showed that  the relative
health  of the eastern and southern re-
gions of Nebraska was similar, as did the
Shannon index of trophic diversity. A ma-
turity index for plant-parasitic nematodes
showed healthier soils in the east, although
its interpretation is controversial.
  Soil pits were dug  at 26  sites to exam-
ine subsurface  indicators.  Two methods
for  assessing soil quality, the Soil Rating
for  Plant Growth (SRPG) and the Soil
Quality Report Card, underwent prelimi-
nary development  using these data. Al-
though different in their approaches, both
provide ways of determining whether soils
are meeting their potential.  The SRPG will
be  best  used  for  regional   monitoring,
whereas  the Report Card will  be more
suitable for monitoring specific sites.
Future Directions
  The ARG will continue to develop indi-
cators  for  use  in  a national monitoring
program. This includes further  work on
the indicators explored here, development
of new indicators (we are testing  an insect
indicator in 1994),  and consideration  of
pasture-livestock systems, windbreaks,
and other components  of the agricultural
landscape.  In addition,  we will address
cross-resource  issues  by working  with
other EMAP Resource Groups in the mid-
Atlantic region in 1994-1997.  We are also
expanding our partnerships with other fed-
eral agencies, primarily USDA's National
Agricultural Statistics Service and Natural
Resources  Conservation Service.
  EMAP continues  to play an  important
role in the national effort to base environ-
mental policy decisions  on sound scien-
tific  information.  The  monitoring  and
assessment techniques  being developed
by EMAP are intended to form the basis
for any regional or national monitoring ef-
fort where  determining the  nature and
scope of environmental problems is of in-
terest.
  This research  has been funded by the
United States Environmental Protection
Agency (EPA) through its Office  of Re-
search  and  Development  under  Inter-
agency  Agreements #DW12934170 with
U.S. Department of Agriculture  (USDA),
Agricultural  Research  Service (ARS),
#DW12934747 with  the USDA  National
Agricultural  Statistics  Service,  and
#DW12936168  with the USDA Natural
Resources  Conservation Service, and by
the USDA ARS. It was conducted with our
research partners under the management
of the Characterization Research Division
of the National Exposure Research Labo-
ratory in support  of the EMAP  Program.
Neither  U.S.  EPA  nor  USDA ARS en-
dorses or recommends any trade name or
commercial product mentioned in the full
document to the exclusion of others. They
are mentioned solely for the  purpose  of
description  or clarification.

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  Susan E. Franson is the EPA Project Officer (see below).
  The complete report, entitled "Environmental Monitoring and Assessment Program,
   Agricultural Lands Pilot Field Program Report—1993, "(Order No. PB95-243069;
   Cost: $19.50, subject to change) will be available only from
         National Technical Information Service
         5285 Port Royal Road
         Springfield, VA 22161
         Telephone: 703-487-4650
  The EPA Project Officer can be contacted at
         National Exposure Research Laboratory
         U. S. Environmental Protection Agency
         Las Vegas, NV 89193-3478
United States
Environmental Protection Agency
National Risk Management
Research Laboratory (G-72)
Cincinnati, OH 45268
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