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- ------- 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. ------- 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 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 Official Business Penalty for Private Use $300 EPA/620/SR-95/004 ------- |