ABSTRACT

Soil organic matter is an important component of the ecosystem, influencing both physical and chemical soil properties. The soil organic matter pools in the century model are conceptual, kinetically defined pools which do not correspond exactly with chemical or physical soil organic matter fractions. A new agroecosystem version of the century model has been designed for the simulation of complex agricultural management systems including crop rotations, tillage practices, fertilizer, and irrigation. The prediction of the effects of different agricultural management strategies on soil organic matter levels is one of the main uses of the century model. This chapter compares century model predictions with data from a set of long-term wheat-fallow tillage experiments at Sidney, Nebraska. In 1969 and 1970 experiments were initiated at two locations on the High Plains Agricultural Laboratory research area near Sidney, Nebraska to compare the effects of fallow tillage methods on crop production, soil moisture and nutrient cycling in the wheat-fallow cropping system.