This session presents a comparative biogeochemical analysis of proposed biomass production systems with emphasis on cellulosic feedstocks that are expected to become increasingly important in the future. The session will begin with an overview of the key biogeochemical considerations that bear on the sustainability of proposed biomass production systems. This will be followed by talks on specific aspects including carbon and nutrient balances, water quantity and quality, and nitrogen pollution of waterways. The session will end with presentations on ecological and biogeochemical consequences of land-use change and modeling efforts of scaling-up bioenergy feedstock production from field and small watershed biogeochemistry data. Agricultural row crops, polycultures including native prairies, and short-rotation woody plantations will all be considered, and compared with grain-based biofuels currently produced mainly from corn and soybeans.