Soil surface roughness with different doses of corn residue submitted to simulated rainfall

The objective of this work was to determine the surface roughness and the tortuosity of the soil tilled with different doses of corn residues, and to relate them to simulated rainfall volume. In an Inceptisol, in La Coruna, Spain, in August of 2005, the surface roughness and tortuosity were evaluated in the minimum soil tillage system under simulated rain, with the doses 0, 2, 4, 6, and 8 t ha(-1) of corn residues semi-incorporated to the soil for manual tillage. Eight tests of simulated rain were applied, with 65 mm h(-1) and 60 min each one. The surface roughness and tortuosity were determined before the application of the residue, immediately after the soil tillage and immediately after the 1(st), 2(nd), 4(th), 6(th) and 8(th) tests of the rain. The reduction of the roughness and of the tortuosity, due to rain, decreased with the increase of corn residues doses. The superficial roughness was more strongly influenced, when the effect of land steepness was eliminated, simultaneously, the effects of steepness and of tillage marks for this calculate.