Use of Manure, Compost, and Cover Crops to Supplant Crop Residue Carbon in Corn Stover Removed Cropping Systems

The emerging cellulosic‐based ethanol industry will likely use corn ( Zea mays L.) stover as a feedstock source. Growers wishing to maintain, or increase soil C levels for agronomic and environmental benefit will need to use C amendments such as manure, compost, or cover crops, to replace C removed with the corn stover. The objective of this research was to determine the effect of cover crops, manure, and compost on short‐term C 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–corn rotation with whole‐plant corn harvest, were conducted near East Lansing, MI over a 3‐yr period beginning in the fall of 2001. Carbon amendments were: compost, manure, and a winter cereal rye ( Secale cereale L.) cover crop. Compost and manure amendments raised soil C levels in the 0 to 5 and 0 to 25 cm soil profile but not in the 5 to 25 cm soil profile over the relatively short‐term duration of the study. Total soil organic C (SOC) (kg ha −1 ) in the 0 to 25 cm profile increased by 41 and 25% for the compost and manure treatments, respectively, and decreased by 3% for the untreated check. Compost and manure soil amendments resulted in a net GWP of −1811 and −1060 g CO 2 m −2 yr −1 , respectively, compared to 12 g CO 2 m −2 yr −1 for untreated.