Carbon Movement in Runoff and Erosion Under Simulated Rainfall Conditions
- Richard Lowrance and
- Randall G. Williams
Organic C loss in erosion contributes to depletion of soil organic matter in continuously cultivated soils. Runoff, erosion, and C movement were measured from eight 39.6 m2 plots under simulated rainfall in order to assess C movement from a coastal plain soil. Plots were located at the Univ. of Georgia Coastal Plain Exp. Stn. near Tifton, GA, on a Tifton loamy sand (fine-loamy, siliceous, thermic Plinthic Paleudults). Four soil cover conditions were duplicated on the eight plots: two-row peanuts (Arachis hypogea L.), four-row peanuts, continuous fallow, and bare-bedded. Samples were taken during rainfall simulator events in March, July, and September 1985 and April 1986. Continuous fallow plots had significantly higher C concentrations in runoff and higher sediment concentrations. Sediment from the four-row peanut plots had the highest C content, 5.83%. Total loads of C and sediment and total runoff were about twice as high from the bare-bedded plots. Approximately 1.0% of the total soil C could be moved annually from the continuous fallow plots with a lower percentage from the other treatments. Runoff as well as sediment and C loads were lowest for simulated rainfall during September when peanuts had been inverted and were on the soil surface. Events in March and April produced lower runoff and lower sediment and C loads than events in July. Apparently the residue cover in the spring was more effective at preventing runoff and erosion than the partial crop canopy in July.
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