ABSTRACT
Soil loss through erosion has been associated with losses in soil organic carbon (SOC). Studies on watersheds have shown that SOC is easily lost because it is usually sediment bound. The close association of organic matter with plant nutrients in the soil makes erosion of soil organic matter a strong indicator of the overall plant nutrient loss resulting from erosion. Runoff losses have been determined using different methods, but in spite of these there is no widely accepted procedure. Runoff experiments have often used the whole watershed, or use simulated rainfall on microplots. Improved fallow systems increase soil organic matter and improve soil physical and chemical properties. Most work done to date on improved fallows has concentrated on effect of nutrient mineralization and cycling. Reduced steady state infiltration rates then resulted in increased runoff and soil losses. High rates of soil loss have been attributed to tillage, as conventional tillage using an ox drawn plow destroyed soil structure.
