Tuesday, November 3, 2009
Convention Center, Exhibit Hall BC, Second Floor
Tillage has long been associated with the decline of soil organic carbon (SOC) in soil. It has been proposed that the potential to recapture some of this carbon lost from the soil may be accomplished through a reduction in tillage. Few comparison studies on SOC stocks using neighboring conventional tillage (CT) and no-till NT fields examine cumulative sampling depths, and include information on soil morphology. This study was conducted to determine if the conversion to NT from CT sequesters carbon examining sampling depth and soil morphology between sampling sites. The effects of tillage upon SOC and its relationships between soil texture, and quantitative soil color measurements were also examined. Two 16 and one 8 year NT fields were compared with neighboring CT field of similar management, landscape, and geology in Ogle County, Illinois. Significantly greater stocks in NT were seen at for all cumulative depths sampled below 40 cm at Site 1, 0 to 10 cm and 0 to 50 cm at Site 2, and for all cumulative depths sampled at Site 3. SOC stocks were significantly greater in CT from 0 to 30 cm at Site 1. Significant logarithmic relationships were observed between SOC and percent reflectance (r2 = 0.85 wet, r2 = 0.85 dry), Munsell value (r2 = 0.85 wet, r2 = 0.84 dry), Munsell chroma (r2 = 0.90 wet, r2 = 0.87 dry). Significant linear relationships were observed between SOC and clay (r2 = 0.14), and geometric mean particle diameter (r2 = 0.25). Similar soil morphologies found at Site 3 allow for the assumption that the SOC stocks measured are a result of the change in tillage assuming similar management practices. Site 1 and 2 show differing soil morphologies making the assumption that SOC stocks measured are a result of changing tillage practices difficult. In addition when examining cumulative SOC stocks depths reported can vary the significance of the result.