9419854, PI-PAUSTIAN: Knowledge of soil organic matter (SOM) dynamics is fundamental to understanding the functioning of agricultural ecosystems. The ability to predict nutrient dynamics (including plant growth and nutrient losses) and to assess the long-term sustainability of managed ecosystems rests largely on understanding organic matter turnover and storage in soils. Accumulated evidence from long-term field experiments, tracer studies, and soil process studies indicate that as much as half the SOM turns over on time scales of 10-50 years or less, is the primary determinant of native soil fertility, and is sensitive to management practices. SOM also is key to soil structure and linked to soil aggregates. This intermediate-aged organic matter is thought to be a critical component of fertility of agricultural soils and is the focus of this research project. This research is important for the analysis of management effects on soil quality and the prediction of organic matter and nutrient dynamics in low-chemical input and conventional cropping systems. The research also assists in understanding land management effects on soil carbon where land-use changes are occurring.
