|Tillman, Patricia - Glynn|
Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2006
Publication Date: 11/12/2006
Citation: Sainju, U.M., Schomberg, H.H., Singh, B.P., Whitehead, W.F., Tillman, P.G., Lachnicht Weyers, S.L. 2006. Cover crops and sampling date effect on on-farm soil carbon pools under conservation tillage cotton. American Society of Agronomy Meetings. Paper No. 54-4. Page 51. Interpretive Summary:
Technical Abstract: Cover crops may influence soil C sequestration and microbial activities by providing additional residue C to soil. We examined the influence of legume (crimson clover), nonlegume (rye), blend (a mixture of legumes containing balansa clover, hairy vetch, and crimson clover], and rye + blend mixture cover crops on active and slow pools of soil C the 0- to 15-cm depth from 2001 to 2003 under dryland and irrigated conservation tillage cotton. Active pools of soil C included potential C mineralization (PCM) and microbial biomass C (MBC) and slow pool as soil organic C (SOC). On-farm experiments were conducted in Dothan sandy loam and Tifton loamy sand in Bartow and Tifton, GA. Total aboveground cover crop and cotton C returned to the soil was 9 to 32% greater in rye + blend than in other cover crops in 2001 but was 24 to 59% greater in rye than in blend and rye + blend in 2002. In Bartow, PCM was greater in June 2001 and 2002 than in Jan 2003 but MBC had opposite trend. In Tifton, SOC was greater with rye + blend than with rye and crimson clover and greater in March than in December in 2002. The PCM was greater with blend and crimson clover than with rye and rye + blend in April 2001 and March 2002 but MBC at 0 to 5 cm was greater in rye, blend, and rye+ blend than with crimson clover in April 2001 and March 2002. Greater C input likely increased soil C storage and microbial biomass with a mixture of legume and nonlegume cover crops but lower C:N ratio increased C mineralization with legumes in the spring under irrigated cotton. Decreased soil temperature and/or substrate availability probably reduced microbial activities in the winter than in the spring.