Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 7/28/1999
Publication Date: N/A
Interpretive Summary: No-till practices and cotton acreage are increasing in the southeast. Researchers and producers do not fully understand the water quality implications of this changing agricultural practice. Tillage influences soil properties which in turn influence how water and nutrients move into and through the soil. To gain understanding of how water quality is subsequently impacted, we must understand the runoff and drainage patterns of soils. We studied drainage and runoff patterns of a Southern Piedmont Cecil sandy loam, near Watkinsville, GA, managed under a no-till and conventional-till cotton/rye cropping system, in 1997 and 1998. Twelve nearly level (0-2% slope),instrumented and tile-drained plots, each 10 m by 30 m, were used in the study. Cotton was grown in summer followed by a rye cover crop in winter. No-till plots had more drainage, often 2 to 3 times, than conventional-till plots. From June 1997 to February 1998, 34% of the rainfall drained off from no-till compared to 18% from conventional-till plots. Runoff was more from conventional than no-till plots. In one typical storm in December 24, 1997, 67% of the rainfall was lost as runoff from conventional compared to 38% from no-till plots. These findings are important and should be taken into account in management decisions aimed at reducing adverse water quality impacts from no-till agriculture.
Technical Abstract: No-till practices are being adopted by producers nationwide. But the environmental significance of no-till, especially on water quality, is not fully understood in many regions, including the southeast. Surface and subsurface hydrology processes need to be better understood to make no-till systems sustainable with respect to water quality issues. Drainage and runoff were continuously monitored in 1997 and 1998 near Watkinsville, GA, from a Cecil sandy loam (clayey, kaolinitic, thermic, Typic Kanhapludults) on twelve, 10 m by 30 m and instrumented plots, with subsurface drains from 0.75 to 1 m depth. The plots were managed in a cotton/rye cropping system under conventional-till (CT)and no-till (NT) treatments. Generally, there was more drainage from NT than CT plots-often between 2 and 3 times. About 34% of the rainfall between June 1997 and February 1998 was partitioned to drainage from NT plots compared to 18% from CT plots. In contrast, CT plots sproduced more runoff. In one event in December 24, 1997, 67% of the rainfall was lost as runoff from CT plots compared to 38% from NT plots. Understanding these relationships is crucial in developing agricultural management options in no-till systems aimed at reducing adverse water quality impacts.