Soil Amendments Improve the Carbon Footprint and Global Warming Potential of Corn Stover Removal.

Carbon cycling and the global warming potential (GWP) of bioenergy cropping systems with complete biomass removal is of agronomic and environmental concern.  Corn (Zea mays L.) growers who plan to remove corn stover as a feedstock for the emerging cellulosic ethanol industry will benefit from carbon amendments such as manure and compost, to replace carbon removed with the corn stover.  The objective of this research was  to determine the effect of beef cattle feedlot manure and composted dairy manure on short-term carbon sequestration rates and net global warming potential (GWP) in a corn soybean [Glycine max (L.) Merr.] rotation with complete corn stover removal.  Field experiments consisting of a corn-soybean rotation with whole-plant corn harvest, were conducted near East Lansing, MI over a three year period beginning in 2002.   Compost and manure amendments raised soil carbon (C) at a level sufficient to overcome the C debt associated with manure production, collection and storage, land application, and post-application field emissions.  Net GWP for the manure and compost amended cropping systems was -998 and -1672 g CO₂ m^-2 y^-1, respectively, compared to 47 g CO₂ m^-2 y^-1 for the non-manure amended synthetic fertilizer check.  This work further substantiates the environmental benefits associated with renewable fuels and demonstrates that with proper management, the integration of livestock manures in biofuel cropping systems can enhance greenhouse gas (GHG) remediation.