Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 6, 2003
Publication Date: N/A
Technical Abstract: Management practices can have major impacts on soil organic carbon levels, gains, and losses. There is wide acceptance that cultivating native land causes loss of soil organic matter. Among the multiple pathways of C loss from agricultural fields is C lost with sediment. To see whether some management practices would more effective in reducing C loss with sediment, different practices (e.g. no-till, chisel-plow, paraplow, and disk) were compared. Carbon concentrations on sediment lost from small watersheds with these practices varied little with time. Tillage practices and weather had major impacts on soil loss from field scale watersheds; however, they had much less impact on sediment C concentration. Management systems that control sediment loss have greater impact on reducing C loss via erosion than those that might change sediment C concentration. Annual concentrations of total organic carbon (TOC) in lysimeter percolate from a corn/soybean-rye rotation and in springflow from pastured watersheds ranged between 0.5 and 3.2 ppm. These concentrations are low in the range of published TOC concentrations in stream flow. No major trends in TOC concentrations were observed during the 10-yr period for either management treatment. Annual average losses of TOC were similar for both management practices, ranging from 1.1 to 4.4 lbs/ac. TOC leaching losses are small compared with other pathways. Thus, in selecting management practices to reduce carbon loss, practices should be selected to reduce sediment loss instead of trying to reduce C carbon concentrations on sediment. This information is important to producers, NRCS and Extension personnel who are involved with developing and using comprehensive management plans.