There is expanding interest in harvesting of crop biomass for energy. Crop biomass such as corn stover, wheat straw, soybean straw or other crop straws can be used as feedstock to support several bioenergy platforms (cellulosic ethanol, gasification or pyrolysis). There are potential benefits to using recently the fixed-C found in biomass for renewable energy compared to using fossil fuels. Biomass for bioenergy may be C-neutral, reduce greenhouse gas load and reduced dependency on foreign oil imports. However, there are environmental risks that must be addressed as the biomass industry develops. The primary roles of crop biomass are to protect the soil from erosion, and provide carbon inputs to support the below ground ecosystem and thus build and maintain soil organic matter (SOM)/soil organic carbon (SOC). Therefore, soil and water conservation benefits must be included in any biomass assessment to prevent long-term environmental damage as the nation addresses short-term energy problems. The big question is how much biomass must stay on the field to provide these ecosystem services. The literature provides initial estimates of the biomass inputs needed to maintain SOC, which can be considerably more than the amount needed to minimize erosion. Grain yield and harvest index can be used to estimate if sufficient biomass is available for protecting the soil resource, then by difference what may be available for other uses. Current research establishing biomass harvest guidelines and/or other management strategies that preserve the capacity of our soil to produce food, feed, fiber, and fuel will be discussed.
Jane Johnson - Jane Johnson is a research soil scientist with the USDA-Agricultural Research Service at the North Central Soil Conservation Research Laboratory, in Morris MN, serving since 2000. She was previously Assistant Professor at the University of Wisconsin-Stevens Point, Biology Department, teaching plant physiology and non-major introductory biology. Her education is: PhD in Plant Biology, MS in Soil Science at the University of Minnesota, BA in biology/chemistry from the University of Minnesota, Morris. Jane's research is in several inter-related areas concerning carbon sequestration, trace gas emissions, carbon and nitrogen cycling, role of biomass for energy and impacts on soil quality and productivity. She is involved in two USDA-ARS multi-location projects: Renewable Energy Assessment Program (REAP) and Greenhouse Gas Reduction through Agricultural Carbon Enhancement Network (GRACEnet). A goal of REAP is to establish biomass harvest guidelines that protect the soil natural resource. The goal of GRACEnet is to enhance the understanding of how agricultural management can reduce its contribution to greenhouse gas emission and sequester carbon in the soil.