%0 Journal Article %A T.C. Strickland %A C.C. Truman %A B. Frauenfeld %T Variable rainfall intensity effects on carbon characteristics of eroded sediments from two coastal plain ultisols in Georgia %D 2005 %J Journal of Soil and Water Conservation %P 142-147 %V 60 %N 3 %X Carbon loss and the associated potential for facilitated transport of chemicals could be better quantified if effects of storm intensity variation could be characterized during key phases of the production year. We evaluated the effects of constant and variable rainfall intensities on the transport characteristics and amount of sediment organic carbon lost from two highly weathered Coastal Plain soils in Georgia—a Tifton loamy sand (Plinthic Kandiudult) and a Greenville sandy clay loam (Rhodic Kandiudult). Soils were air-dried, sieved (19 mm) and placed in 1.5 m2 stainless steel erosion pans set to match typical field slopes for each soil (Tifton = 4 percent; Greenville = 7 percent). Simulated rainfall was applied for 70-min as a constant (57 mm h−1) or variable (typical spring storm) event pattern. Runoff, sediment, sediment carbon, sediment nitrogen, and dissolved carbon were measured at five-minute intervals. Regardless of simulation intensity evaluated, sediment exported from the Tifton soil was enriched (enrichment ratio 1.17 to 1.80) and the Greeneville soil depleted (0.83 to 0.93) in carbon relative to the top 2 cm of undisturbed soil. Only minor (not significant) differences were observed in the potential for total sediment carbon loss estimated by the two simulation intensities (Tifton, 5.65 – 6.67 kg ha−1 and Greenville, 13.44 – 14.40 kg ha−1). However, significant differences in the effect of simulation intensities on timing and amount of carbon lost via sediment transport (more during first versus second half of simulation for variable versus constant intensity patterns respectively) were observed during the simulations. Results suggest that detachment and transport thresholds differ for total sediment versus sediment carbon losses during a given event and that variable rate rainfall simulations may be an effective means to characterize threshold differences for individual soil and management combinations. It is suggested that the systematic determination of such thresholds may improve predictions of sediment transported organic contaminants. %U https://www.jswconline.org/content/jswc/60/3/142.full.pdf