ABSTRACT:
The PC-based model for predicting tillage and crop rotation effects on organic carbon decomposition and storage in the soil as organic matter (OM) uses crop residue and root biomass production, tillage type and timing, and average temperature from existing c-factor files, created with the Revised Universal Soil Loss Equation (RUSLE). Residue nitrogen content and soil Layering information-including layer thickness, organic matter content, and bulk density-complete the input requirements for the model. Short-term trends of surface and remaining buried residue and Long-term trends in soil organic matter content, are computed for individual fields and cropping practices. The model was calibrated with soil organic carbon observations (converted to equivalent OM values) from plots with over 60 years of recorded management history including wheat/fallow with manure additions and wheat/fallow with stubble removal. Computations have a 95% confidence interval of +/-3.3 g OM kg−1 soil (0.33% OM). Comparison of OM calculations from the calibrated model with observed values from Lancaster, Wisconsin, and Lexington, Kentucky, produced mean residual errors ranging from -3.O to + 0.2 g OM kg−1 soil (-0.3 to + 0.02% OM.
Footnotes
Ron W. Rickman and Clyde L. Dough, Jr. are soil scientists and Steve L. Albrecht is a soil microbiologist with the U.S. Department of Agriculture, Agricultural Research Service in Pendleton, Oregan. Larry G. Bundy is a soil scientist with the Department of Soil Science at the University of Wisconsin in Madison, Wisconsin. Jeri L. Berc is special assistant to the deputy chief of Soil Survey and Resource Assessment for the U.S. Department of Agriculture, Natural Resources Conservation Service in Washington, D.C.
- Copyright 2001 by the Soil and Water Conservation Society
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