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A Framework for Regional Agroecosystems Characterization Using the National Resources Inventory

USDA-ARS, 232 National Soil Tilth Lab, 2150 Pammel Dr., Ames, IA 50011;

S. L. Oberle

USDA-ES, 214 National Soil Tilth Lab, 2150 Pammel Dr., Ames, IA 50011;

M. J. Hewitt

USEPA, Environmental Monitoring Systems Lab, P.O. Box 93478, Las Vegas, NV 89193;

J. Pickus

Lockheed Environmental Systems and Technologies Co., 980 Kelly Johnson Dr., Las Vegas, NV 89119.

^* Corresponding author (mburkart{at}iastate.edu).

ABSTRACT

An agroecological framework is used to examine the relations among natural resources and agriculture. Spatial representation of selected agroecosystems characteristics was accomplished using the National Resources Inventory (NRI). Natural resource and anthropogenic variables from the NRI were spatially aggregated to produce maps showing the regional variability in area-weighted values of agroecosystem components. Maps of natural vegetation, agricultural land use, crop diversity, artificial drainage, irrigation, net soil loss, and conservation practices show the extent to which resources have been modified to support agriculture in the Midwest. The frequency of land used for crops and pasture exceeds 70% in much of the region. Natural vegetation occupies less than 10% of the land in many areas. Subsurface and surface drainage, more than 35% of some areas, has contributed to loss of wetlands having a direct effect on water quality. Irrigation has diverted water from natural ecosystems and increased the potential for leaching of agrichemicals. Excess erosion may threaten long-term productivity in parts of the region even though conservation practices have been implemented. Examination of these and other elements in an agroecosystem framework may be useful in the search for systems to sustain agriculture and natural resources in the region. Such a framework can also be used to locate areas where mitigation of degraded resources is most needed; identify areas where research into causes of degradation can yield the most information; and where policies to improve off-site damage may be most effectively implemented.