ABSTRACT
Soil organic matter content is the result of a steady-state equilibrium of formation and degradation, which can be affected by soil management practices. This chapter describes the long-term effects of Nitrogen (N) fertilization and legume-cereal crop rotations on soil productivity and carbon (C) and N dynamics in two Wisconsin soils typical of the northern US Corn Belt. The field study is located on the University of Wisconsin Arlington Agricultural Research Station in south central Wisconsin, approximately 25 km north of Madison. The alfalfa-bromegrass meadow grown at the Lancaster site for many years prior to establishment of the experiment may have had a major role in the relative losses of C observed during the subsequent continuous corn culture. In 1984, the long-term N treatments were discontinued and each of the original plots was subdivided to determine the residual effects of the long-term N fertilizer treatments on corn response to N fertilization.
