SUMMARY: We still need an answer to the critical question: ?How much crop biomass is needed to protect and maintain the soil resource, and correspondingly, how much can be harvested as renewable fuel? Through photosynthesis and the processes of growth and translocation, plants use solar energy to transform carbon dioxide and water into grain and biomass.The latter is useful for nurturing the soil biology, maintaining soil properties important in soil quality, and also as a bioenergy feedstock. A practical compromise is needed for crop biomass to function effectively in the competing roles of soil conservation and renewable energy production. Economics and government policy will drive development of biomass for biofuel industries. However, we cannot afford to overlook the potential costs associated with wide-scale removal of crop residues from the land.These costs may not be readily apparent in the short term and economic impacts are not easily quantified. Thus far, farmers are not compensated based on the ecosystem services provided by agricultural watersheds. We suggest a cautious approach to harvesting crop biomass for energy until science-based research provides answers and guidance to the critical questions of how much,when, and where to harvest crop biomass. Research is needed to provide land managers, the biomass industry, and action agencies with sound, scientifically based, field-tested guidelines for sustainable production and harvest of crop residues. This need is especially critical in light of the current economic pressures to find alternative energy sources and the short time-frame set by DOE for domestic renewable fuels to become a significant contributor to the nation's energy and product supply. As the biomass energy industry develops, we strongly encourage soil and energy conservation to achieve sustainable energy security.
