Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2007
Publication Date: 3/10/2008
Citation: Roberson, T., Reddy, K.C., Reddy, S.S., Nyakatawa, E.Z., Raper, R.L., Reeves, D.W. 2008. Carbon Dioxide Efflux from Soil with Poultry Litter Applications in Conventional and Conservation Tillage Systems in Northern Alabama. Journal of Environmental Quality. 37:535-541. Interpretive Summary: The Kyoto Protocol, a document which advises developed nations to reduce greenhouse gas, allows developed nations to meet their reduction limits by soil C sequestration. Soil conservation practices which increase soil organic C levels include conservation tillage, applying manures such as poultry litter, and planting cover crops such as winter rye [Secale cereale (L.)]. Our study showed that application of poultry litter in no-tillage systems increased soil organic carbon by 11 % in comparison to total carbon in conventional tillage in just two years. For the 230,000 acres of cotton in the Tennessee Valley, poultry litter applications made to no-tillage systems with a winter cover crop is an effective way to increase soil carbon and mitigate CO2 emissions to the atmosphere.
Technical Abstract: Increased carbon dioxide release from soils resulting from agricultural practices such as tillage and application of poultry litter in cotton production systems has generated concerns about contributions to global warming which negatively impacts natural ecosystems, weather patterns, and food production. We conducted a study in north Alabama in 2003 and 2004 to measure carbon dioxide efflux and carbon storage in long-term tilled and non-tilled cotton plots receiving poultry litter and ammonium nitrate as nitrogen sources. Treatments were established in 1996 on a Decatur silt loam and consisted of conventional-tillage, mulch-tillage, and no-tillage systems with winter rye cover cropping and ammonium nitrate and poultry litter sources of nitrogen. In 2003, carbon dioxide efflux in conventional tillage plots averaged from May through October 16% and 63% significantly higher than in mulch tillage and no-tillage, respectively. Also, in 2004, carbon dioxide efflux in mulch-tillage averaged 14% and 33% greater than conventional tillage and no-tillage, respectively. At the conclusion of this study, soil carbon content was 10% and 7% higher in no-tillage than in conventional tillage and mulch-tillage plots, respectively. On average, no-tillage can reduce soil carbon dioxide emissions by when compared to conventional tillage systems during the cotton growing season of about 165 days. Our study suggests that no-tillage conservation tillage systems along with application of poultry litter at the rate of 100 or 200 kg N ha-1 promotes carbon storage in soil and thus reduces atmospheric carbon dioxide increases.