The increasing societal need for renewable energy from the agricultural sector offers new opportunities and challenges as we redefine ecosystem goods and services in view of sustainable land use and management under changing climates. Corn stover is the combination of all aboveground components of the corn plant, except for the corn seeds. In other words, stover is the residue that consists of stalk, leaves, husks, and cobs of corn remaining in the field following the harvest of corn seeds. Corn stover is a common agricultural product in areas that have large amounts of corn production. There is a great potential for using corn stover as a feedstock for biofuel production in the United States, but harvesting excessive amounts of corn stover could have long-term negative impacts on soil quality, soil carbon stock, and nutrient balances. The challenge is to develop cropping systems that can balance the demand for increased biofuel feedstock production with the maintenance of other critical ecosystem services.
This project was designed to evaluate the extent to which the corn stover can be sustainably harvested as cellulosic feedstock for biofuel production and its impacts on soil organic carbon (SOC) and nutrient budgets in the conterminous United States at present and in the future.
The magnitude of the current harvestable stover amount is limited (31 x 1012 g y-1, dry matter) due to the high minimum stover requirement for maintaining the current SOC content at a high level. An alternative definition of minimum stover requirement for soils with a moderate level of SOC content could significantly increase the annual harvestable stover amount to 68 x 1012 g y-1 with no substantial influence on soil organic carbon and soil nitrogen, phosphorus, and potassium contents. In the future, a greater potential for stover feedstock could come from an increase in stover yield, areal harvest index, and manure application.
County-based harvestable stover yields at present (2013) and in 2050.