Carbon concentrations on sediment lost from watersheds with different tillage practices (e.g., no till, chisel-plow, paraplow, and disk) 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 TOC in lysimeter percolate from a corn/soybean-rye rotation and in springflow from pastured watersheds ranged between 0.5 and 3.2 mg/L. 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 years for either management treatment. Annual average losses of TOC were similar for both management practices, ranging from 1.2 to 14.9 kg/ha. TOC leaching losses are small compared with other pathways.
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