Tillage system effects on runoff and sediment yield in hillslope agriculture

Runoff and soil erosion are major factors of land and lake degradation in t he Patzcuaro Watershed located in Michoacan, Mexico. This non-point source pollution results from corn cultivation on steep cropland sites. In the loc al farming system, the soil is bare for much of the year and subject to fre quent plowing and cultivation. Conservation tillage and the use of crop res idues for soil protection have only recently been introduced in this region , Runoff plots (25m x 4m) were used to collect runoff (Q) and sediment yiel d (Sy) data to identify a tillage system that allows soil restoration. The groundwater loading effects of agricultural management systems (GLEAMS) mod el was calibrated using runoff and sediment information from four tillage t reatments that evaluated soil erosion and estimate the long-term sustainabi lity of current and alternative fanning systems. Four runoff plots planted with rainfed corn were used for these treatments: (1) conventional tillage (CT), (2) no-tillage without residue cover (NT-0), (3) no-tillage with 33% residue cover (NT-33), and (4) no-tillage with 100% residue cover (NT-100). The results indicated that CT and NT-0 treatments produced higher Q and Sy than those having residue cover. Simulated Sy of NT treatments was much be tter than simulated Sy of CTI based on their agreement with observed Sy, Th ese results are relevant to recommend no-till agriculture as Best Managemen t Practice for agricultural land requiring restoration activities. (C) 2001 Elsevier Science B.V. All rights reserved.