Rainfall and runoff together are the active agents of water erosion, furthermore influenced by soil cover and roughness, crop and soil tillage. Compared to conventional tillage, water erosion is reduced in soil conservation tillage because this method is less intensive, preserves the cover longer, and sometimes increases soil roughness. Erosion losses (soil and water) of a clayey Hapludox with a slope of 0.09 m m-1 were evaluated in Chapecó, Santa Catarina State, Brazil, from November 1994 to October 1999 under natural rainfall. The treatments, in two replications, consisted of the following downslope soil tillage systems: no-tillage, conventional tillage, minimum tillage, and tillage rotation, with some summer and winter crop rotation combinations, and conventional tillage without crop (standard unit of the Universal Soil Loss Equation-USLE) as control. In no-tillage with crop rotation there was a soil loss reduction of 45 % in relation to summer conventional tillage and to winter no-tillage crop rotation systems, and of 99 % in relation to bare soil. Conservation tillage reduced the mean soil loss by 80 % in relation to conventional tillage. Mean soil losses were twice as high during the spring/summer as in the fall/winter period in no-tillage treatments, while in the other treatments average losses of the crop years were 3.3 higher in fall/winter. Water losses were small, with a behavior similar to that of the soil losses, in spite of the quantity difference.
water erosion; conservation tillage; tillage rotation; crop rotation; no-tillage
