Influences of Bioenergy Crops on Soil C Dynamics in the Lower Mississippi Alluvial Valley.

The Lower Mississippi Alluvial Valley is a robust agricultural region capable of growing a wide array of crops.  Public and private investments in bioenergy are concerned not only with efficiently converting crops into fuels but also the carbon footprint of bioenergy crop production.  Soil carbon is the largest terrestrial pool of carbon and a vital component of the carbon footprint of bioenergy crop production.  Soil carbon dynamics associated with bioenergy crop production can be influenced by several management factors, including the conversion of land uses into bioenergy crop production, the bioenergy crop selected, harvest practices, organic matter retention, and fertilization practices.  A series of ongoing trials in the Lower Mississippi Alluvial Valley on sweet sorghum, switchgrass, and cottonwood include these management factors.  In each trial, key pools of soil C (total C, labile C, microbial biomass C, carbon dioxide emissions from soil respiration, soil organic matter C) are being observed.  This presentation will provide a synthesis of changes in these soil C parameters in each of these energy crops.