SOIL SURFACE ROUGHNESS UNDER DIFERENT MANAGEMENT SYSTEMS AND ARTIFICIAL RAINFALL

Soil roughness is influenced by soil management, particularly by soil tillage and mainly reduced by rainfall action. This study aimed to evaluate the influence of different systems of sod management and artificial rainfall application on soil surface roughness. The treatments were a result of the combination of three systems: no-tillage, conventional tillage and minimum tillage, with three levels of dry soybean (Glycine max L. Merrill): residue: 0; 2; and 4 Mg ha(-1). Experimental units received artificial rain (seven rains), at an intensity of 60 mm h(-1) and during 60 milt each, amounting to 420 mm rain. Roughness was evaluated immediately before and after tilling and immediately after the rainfalls. Roughness values between 1.88 and 5.41 mm were found under no-tillage 7.88 and 8.30 mm under conventional tillage, and 3.31 and 17.45 mm, under minimum tillage. It was concluded that sod tillage operations generally increased surface roughness. Values of random roughness were highest under minimum. tillage; rain did not deteriorate the soil microrelief in the no-tillage treatments with sod cover.