The Agronomic and Environmental Costs of Removing Corn Stover.

The harvesting of crop residues for ethanol production, bedding supplies, or feed  have been proposed as a technique to reduce costs and increase profitability.   However,  crop residue harvesting can also reduce soil organic carbon levels and productivity, while increasing erosion.  The objective of this study was to determine the soil organic carbon maintenance requirements in field studies conducted across the US corn belt.      Maintenance requirements, and SOC mineralization rates (K_SOC), non-harvested carbon conversion rates to SOC (K_NHC) were determined.  Results showed that a simple model can be used to compare data from different sites and that the calculated maintenance requirement and associated rate constants (K_SOC and K_NHC) are sensitive to the initial SOC content and the amount of non-harvested carbon returned to the soil.    Once the rate constants are known, the potential impact of different management scenarios on SOC can be assess by solving the equations, δSOC/δt = K_NHC(NHC_t) – K_SOC (SOC_t) and K_SOC · SOC_e = K_NHC · NHC_m.