From exec summary: "....The basis of the direct and indirect emission calculations is a detailed empirical model that is discussed in the companion report to this work (hereafter referred to as the modified Bouwman model-MBM). The MBM incorporates various factors including quantity of fertilizer used, type of fertilizer, soil texture and drainage, pH and soil carbon concentration to predict nitrous oxide emissions. The companion report shows that the approach of the MBM is not sufficient at the project level, however, for a broad national analysis the approach is ideal....Our analysis resulted in an estimate of total annual N2O emission of 61 million tons of carbon dioxide equivalent for the three crops across the 31 states. Seventy percent of these emissions were from corn fields, 25% from wheat fields and 5% from cotton.
