Escoamento superficial de água no solo em razão de diferentes quantidades de palhada em sistema de plantio direto

Abstract

Surface water runoff in soil, at higher levels, undergoes water erosion, one of the main causes of agricultural soil degradation. These factors are associated with a decrease in the soil's water retention capacity, soil degradation, and displacement of nutrients and organic matter from the surface layer to lower regions of the cultivation area, roads or bodies of water, resulting in siltation processes. Therefore, the objective of this work was to evaluate the effects of different amounts of straw on the soil, on the amount of water that flows and infiltrates the soil. The experimental design used was completely randomized with five treatments and four repetitions, totaling 20 experimental units. The treatments correspond to: without cover - T1; 2 Mg ha⁻¹ of straw DM - T2; 4 Mg ha⁻¹ of straw DM - T3; 8 Mg ha⁻¹ of straw DM - T4; 10 Mg ha⁻¹ of straw DM - T5. Soil samples were collected with preserved structure, using stainless steel rings to evaluate physical properties such as soil density, total porosity, macroporosity, microporosity, and soil samples for granulometric analysis. The soil was classified as Oxisol, with clay contents of 51%, silt 29%, and sand 20% in the 0 to 20 cm layer. The data obtained were submitted to analysis of variance, and the means were compared by Tukey's test, at a 5% probability of error. Straw is efficient in reducing surface runoff and water flow in the soil. There is no significant difference in the treatments of 4, 8, and 10 Mg ha⁻¹ of straw in surface runoff and water infiltration in the soil, demonstrating that levels of 4 Mg ha⁻¹ of straw or more are effective in reducing surface water runoff and increasing water infiltration in the soil. The highest values of surface runoff and water infiltration in the soil were observed in the treatment without cover.