CQESTR - Predicting carbon sequestration in agricultural cropland and grassland soils

Implementation of a national program for increasing organic carbon levels in agricultural soils will ultimately require specific management plans for individual fields throughout the nation. A tool to help create those plans must provide estimates of change in soil carbon as controlled by crop rotation, tillage practices, local climate, and soil. A program named CQESTR (sequester) has been developed by USDA ARS at Pendleton, OR, to fulfill this need. The program uses a budget of carbon-based residue additions and microbial decomposition losses to estimate rate of gain or loss of soil organic matter (OM). Rotation production and tillage practices are obtained from existing data files created and utilized by the revised universal soil loss equation (RUSLE). Residue nitrogen content and soil layer information including depth, bulk density, and starting organic matter content must be obtained independently from the RUSLE data files. The rate of gain or loss of soil carbon was calibrated to long-term management plots from Pendleton. Comparisons with reported soil carbon changes in long-term plots throughout North America have begun.