Biogeochemical Implications of Growing Biomass for Biofuels Feedstock.

Biogeochemical implications of growing biomass for biofuels feedstock A.K. Bhardwaj, K. Kahmark, P. Jasrotia, I. Gelfand, S.K. Hamilton and G.P. Robertson Great Lakes Bioenergy Research Center (GLBRC), W.K. Kellogg Biological Station (KBS), 3700 E. Gull Lake Drive, Hickory Corners, MI 49060 Abstract: Global energy use projections predict that biomass will be an important component of primary energy sources and a main source of renewable energy in the coming decades. To evaluate the sustainability of a biofuel production system, in addition to demonstrating a net positive energy yield, it is important to know the carbon, nitrogen and water balances of the system and their implications for the environment. In this direction, intensive experiments were started at Kellogg Biological Station on potential biofuel crop production systems, through the Great Lakes Bioenergy Research Center (GLBRC). The studies are being conducted on a 22 ha site that has been subdivided into ten treatments representing eight different production systems and three common agricultural practices, each replicated in five blocks. These production systems are studied for productivity, carbon and water balance, and biodiversity effects. A major goal of the initiative is to test and develop biofuel crops that are most environmentally sustainable. A fully automated soil chamber system provides continuous flux measurements of the main greenhouse gases (GHGs: CO2, CH4, N2O). From the measurements of the net productivity of each cropping system, and GHG fluxes associated with agronomic practices and soil activity, the GHG balances will be estimated. Soil water profiles and nutrient fluxes to groundwater in the treatments are being monitored continuously with automated Time Domain Reflectometry (TDR) systems and lysimeter samplers, respectively. Growing-season samples are being taken for nutrient availability, above- and below-ground productivity, and soil properties. The net energy yield of biofuel production will be estimated from the energy costs of the field maintenance and biofuel production. Our overarching objective is to generate a comprehensive portrait of the production potential as well as environmental implications of the various candidate cropping systems for cellulosic ethanol production.