Submitted to: USDA Greenhouse Gas Symposium
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 2006
Publication Date: February 6, 2007
Citation: Sainju, U.M., Caesar, T., Lenssen, A.W., Evans, R.G., Kolberg, R.L. 2007. Long-term tillage and cropping system effects on dryland soil carbon sequestration and fractions. Positioning Agriculture and Forestry to Meet the Challenges of Climate Change. In Fourth USDA Greenhouse Gas Conference. February 6-8, 2007. Baltimore, MD. p.38. Technical Abstract: Management practices are needed to increase dryland soil C sequestration for C trading to reduce greenhouse gas emission and C fractions to improve soil quality. We evaluated the 21-yr effect of a combination of tillage frequency and cropping intensity [No-till continuous spring wheat (NTCW), spring till continuous spring wheat (STCW), fall and spring till continuous spring wheat (FSTCW), fall and spring till wheat-pea/barley (FSTW-P/B), and spring-till spring wheat-fallow (STW-F)] on soil surface residue C and soil C fractions in 2004 in eastern Montana. Mean annualized straw C returned to the soil from 1984 to 2004 was lower in STW-F than in other treatments. As a result, surface residue C was also lower in STWF than in NTCW and FSTCW. Soil inorganic (SIC) and organic (SOC) C, particulate organic C (POC), and potential C mineralization (PCM) at the 0 to 5 cm depth were higher in NTCW, STCW, and FSTCW than in STW-F. At 5 to 20 cm, SOC and POC were higher in NTCW and STCW than in STW-F, and PCM was higher in STCW and FSTW-P/B than in STW-F. No-tillage increased annualized straw C, SIC, SOC, and PCM at 0 to 5 cm, and POC at 0 to 5 and 5 to 20 cm compared with tillage. Similarly, continuous cropping increased annualized straw C, residue C, SIC at 0 to 5 cm, and SOC, POC, and PCM at 0 to 5 and 5 to 20 cm compared with crop-fallow. Reduced tillage and increased cropping intensity increased dryland C input, C storage in soil and residue, and C fractions that help to increase C sequestration and soil quality.