Conservation Tillage Systems and Fertilizer Management Practices for Reducing Soil Carbon Dioxide Emissions.

Land application of poultry litter (PL) as a fertilizer in no-till (NT) conservation tillage provides an option for animal waste disposal in the southeastern U.S. However, soil and fertilizer management strategies for reducing emissions of carbon dioxide (CO₂) in NT systems are required to ensure an environmentally sustainable production system. This paper discusses CO₂ emissions in a soil receiving PL and ammonium nitrate (AN) fertilizers for corn (Zea mays L.) production in no-till (NT) and conventional tillage (CT) systems, using surface (SA), soil incorporation (SI), and subsurface band application (BA) methods, on a Decatur silt loam soil in north Alabama. Soil gas samples were collected using custom built static chambers and analyzed for CO₂ gas concentrations for calculating soil gas fluxes. The highest Net soil CO₂ flux of 22.8 mg m^-2 min^-1 was observed in CT plots with soil incorporation of PL (CT-PL-SI), followed by fluxes in NT with surface application of AN (NT-AN-SA), conventional till with surface application of PL (CT-PL-SA), and no-till with surface application of PL (NT-PL-SA), which had a mean net flux of 8.7 mg m^-2 min^-1 from April 2008 to March 2009. Net CO₂ fluxes in the other treatments, which averaged 5.4 mg m^-2 min^-1 were similar to that from a control undisturbed grass plot. Our study shows that subsurface band application of PL in NT conservation tillage system can reduce soil CO₂ emissions by up to 50% compared to surface application in both CT and NT systems, and by up to 300% compared to soil incorporation of PL in CT system.