This chapter presents an agroecological approach for assessing crop and soil management effects on the sustainability of the soil resource. Crop yield, soil profile N concentrations, denitrification, earthworm populations, infiltration, soil aggregation, and microbial biomass were indicators measured to evaluate the agroecosystem response to alternative management practices used on the Thompson farm in central Iowa. Corn and soybean are the only crops grown on the conventionally managed Baker farm, so only limited yield comparisons are possible. Corn has been grown continuously since 1964 on three of the four U.S. Department of Agriculture‐ARS Deep Loess watersheds and on the fourth watershed since 1972. Crop and soil management practices that preserve or increase surface crop residues and soil organic matter seem to be desirable for long‐term sustainability of the soil resource, even in the traditionally highly productive agroecosystems such as the U.S. Corn and Soybean Belt.