Resumen de Soil surface roughness under tillage practices and its consequences for water and sediment losses

Paulo Roberto da Rocha Junior, Rabin Bhattarai, Raphael Bragança Alves Fernandes, Prasanta Kumar Kalita, Felipe Vaz Andrade

• The present study aims to determine the effects of soil management practices on soil surface roughness and the consequences of these phenomena on water and sediment losses. Laboratory experiment was conducted on a Chernozems clayey soil subjected to a sequence of two 30 min simulated rainfall of 50.8 mm h-1 and 114.3 mm h-1and four soil management practices: contourtillage (CT), downhill tillage (DT), no-tillage simulated (NTs) and bare soil (BS). Soil surface roughness was evaluated using a laser distance meter. Results showed that the soil tillage in downhill or contour increased soil roughness by 2.90 and 2.76, respectively, reducing the water losses under low rain intensity by 12.8% and 6.4%. Soil surface roughness quickly changed after the onset of rain, and higher values of changes in soil roughness were observed for contour (22.73%) and downhill tillage (21.05%) managements. Soil coverage factor and the direction of tillage were the most important characteristics in contrast with soil surface roughness to reduce the sediment losses. No-tillage simulated (0.59 tha-1) and contourtillage (1.30 t ha-1) were the soil management practices with lower sediment losses compared to other managements studied. The principal theoretical implication of this study is that land use planning with agriculture, livestock must be designed to prevent the soil from being exposed, or if exposed, tillage in contour should be adopted. The input of litter on soil surface had an important role in reducing the sediment and water losses.