In conservation tillage systems, the residue cover and surface soil roughness decrease runoff and allow increased terrace distance, as compared to conventional tillage systems, in spite of the increase of surface consolidation which occurs especially in no-tillage systems. The distance between terraces should not allow runoff between them since this would cause residue removal and increased erosion as well as a runoff volume or rate higher than the terraces'-channel capacity. The distance between terraces was determined at the Agronomic Experimental Station at the UFRGS, in Eldorado do Sul (RS), Brazil, from 1992 to 1994. Simulated rainfall and extra inflow on no-tillage and chiseling systems were used with corn, wheat and corn + wheat residues, in a Paleodult soil with 0.066 m m-1 slope steepness. Based on the criterion of water storage capacity at the terrace channel, the smallest distance between terraces (27 to 43 m) was determined for chiseling with the corn residue, and the largest distance (44 to 60 m) for no-tillage with corn residue. Based on the criterion of residue failure, the smallest distance between terraces (106 to 130 m) was for no-tillage with wheat residue and the largest distance (328 to 483 m) for no-tillage with corn residue.
soil no-tillage system; soil chiseling system