Tillage effects on rainfall partitioning, sediment yield, and facilitated agrichemical transport potential

摘要

Coastal Plain soils located in the southeastern U.S. have been intensively cropped and traditionally managed under conventional tillage practices. They are susceptible to erosion, resulting in transport of pollutants to off-site water supplies through colloidal facilitated transport of agrichemicals. The objective of this study was to quantify rainfall partitioning, sediment delivery and characterization, and enrichment of clays between sediments and in situ soils from a Typic Hapludult loamy sandmanaged under conventional-till (CT), no-till (NT), and para-till systems. Plots (1 m~2) established on each tillage system treatment were exposed to simulated rainfall for 2 h with an intensity of 50 mm h~(-1). Runoff and sediment-delivery were continuously measured from flat, level-sloping field plots (slope=1 percent). More runoff (45 percent vs. 72 percent) and sediment losses (3 fold) occurred from CT plots compared to NT plots. Removing residue from NT and CT plots increased runoff (38-48 percent)and sediment (2-5 fold) losses compared to corresponding plots with residue. Para-tilling decreased runoff (by up to 50 percent) and sediment (2 fold) losses compared to non-para-tilled plots. Amount of water dispersible clay (WDC) was correlated with percent OC (R~2=0.76), which was a function of tillage treatment. Sediments were enriched in quartz and depleted with respect to kaolinite as compared to in situ soils.