Variation of Runoff Characteristics Under Conservation Tillage Systems

Abstract

ABSTRACT Tillage systems of cotton were studied for three years to determine differences between their effects on four parameters of runoff characteristics: runoff volume, runoff as percent of rainfall, peak flow rate, and SCS runoff curve number. The tillage systems included: reduced tillage without a cover crop (RT), reduced tillage with a winter wheat cover crop (RTC) and conventional tillage (CT). Three paired tests of the tillage systems (RT vs. RTC, CT vs. RT, and CT vs. RTC) were used to evaluate differences between effects. Statistical comparisons were conducted for three data sets separately; all storm events, storm events during the growing period (planting to the last harvesting), and storm events during the non-growing period. The runoff parameters were affected by the three tillage systems and these effects varied by the periods. Effects of the storm events on the runoff parameters were higher during the growing period than during the non-growing period. The RTC system was the most effective in reducing runoff volume and peak flow rate. All runoff parameters of the CT system other than the runoff as percent of rainfall were not different from those of the RT system. The SCS runoff curve number from RT and CT were higher than RTC for all storm events. No difference was found for this parameter between CT and RT.