The success of soil conservation tillage systems to control water erosion is related to the amount of crop residue and percentage of soil surface coverage. Residue persistence after harvesting is important to maintain soil coverage, which affects soil physical-hydric properties and runoff. The study was conducted in Santa Catarina State, Brazil, with the purpose of evaluating oat and corn residue persistence on soil surface under no-tillage system. The trial was carried out from October of 1995 to December, 1996, using two no-tillage experiments located in Lages, on alic Humic Cambisol (Inceptisol), and in Lebon Regis, on structured Brown Earth (Kandihudult). Oat and corn residue samples were collected during a period of 180 and 225 day, respectively, in a 0.24 m² area within each experiment, at a regular 45 day interval. Samples were dried and then weighed for evaluation of mass. After the 180 day evaluation period, the oat residue presented an 80% decrease in dry weight and a 60% decrease in soil surface coverage at both study sites. Corn residue was reduced by 64% and 80% in Lages and Lebon Regis, respectively, and soil surface coverage diminished by 40% at both sites, after the 225 day evaluation period. The decomposition rates of oat and corn residue were 100 and 90% greater, respectively, in the first 45 days than in the remaining experimental period, as an average of the two study sites.
conservation tillage; crop mass; crop persistence; crop decomposition