Surface Runoff and Sediment Yield from Various Tillage Systems of Cotton

ABSTRACT THREE tillage systems of cotton were studied to determine their effects on surface runoff and sediment yield during growing period of 1985 and 1986 in the Tennessee Valley region of northern Alabama. They include; reduced tillage without a cover crop (RT), reduced tillage with a winter wheat cover crop (RTC) and conventional tillage (CT). Sediment yield was in the order of CT > RT > RTC in 1985. Runoff was the lowest from the RTC system followed by the CT and RT systems. In 1986, runoff from the CT was the lowest, followed by the RTC and RT, while sediment yield was in the order of CT > RTC > RT. The growth stage of cotton and the cultivations of the CT system influenced the patterns of runoff and sediment yield. More than 85% of the measured sediment yield and 50 to 70% of the runoff occurred during the first 2 months after planting. Seed cotton yields for all tillage systems were above average in 1985, but the highest yield occurred with the RT system. However, a drought during the critical stage of growth in 1986 caused reduced yield with all systems and the lowest yield occurred with the RT system.