Estimating the Soil Carbon Response to Cropping Intensity, Crop Rotation and Residue Harvest.

Agricultural residues are a sizeable potential source of cellulosic feedstock for biofuel production capable of feasibly providing near-term feedstock without requiring land conversion or displacing food production. However, residue harvesting has been shown to reduce soil carbon levels, negatively affecting soil health and limiting the ability of residue-derived biofuels to meet the Energy Independence and Security Act (EISA) emissions standards for cellulosic biofuels. Research has demonstrated the capacity to increase soil carbon stocks through increased cropping intensity and complexity. Thus consideration of traditional cropping rotations as well as inclusion of cover crops or double crops in crop rotations could appreciably affect the greenhouse gas (GHG) intensity and soil health impacts of residue-derived biofuels. Here we conducted a literature search to identify experiments measuring soil carbon levels under various crop rotations, cropping intensities and residue management practices. The dataset was used to evaluate the Environmental Policy Integrated Climate (EPIC) model, which was then applied to estimate the impacts of crop rotation, cropping intensity and residue harvest on soil carbon levels and the GHG intensity of residue-derived biofuels.