Erodibilidade em entressulcos e encrostamento superficial em Solos do Semiárido sob aplicação de gesso agrícola

Abstract

Soils in the world present problems of water erosion due to the impact of the rain drop on the soil surface, aggravating the superficial crusting and erodibility of the soils. However, agricultural gypsum acts as a reducer of surface crusting, by promoting the flocculation of clays, increasing the stability of aggregates and reducing dispersion. The objective of this study was to evaluate the erodibility of entresulcos and superficial crusting in semi-arid soils under the application of agricultural gypsum. By means of simulated rainfall tests, experiments were carried out to measure the erosion of entresulcos, under open soil conditions with and without the application of agricultural gypsum. The experimental plot has a useful area of 0, 3481m2 and a slope of 0.10 mm-1. The rains were simulated at intervals of 0, 7, 14, 21 days, with mean mean intensity of 85 mm h-1 for 75 minutes. Hydraulic flow variables, disintegration rate, total soil losses, erodibility, suspended sediments, surface roughness, surface crusting, crust microtexture and aggregate stability were evaluated. The soils presented laminar regime and subcritical flow, characterizing the formation of erosion in entressulco. The highest disaggregation rates, soil losses and suspended sediments in TCo and RLe occurred in test 1, due to the direct impact of the rain drop, and intrinsic characteristics of each soil. The erodibility was reduced when agricultural gypsum was applied, due to the flocculating effect of the interaction between the colloids of the RL and greater susceptibility to surface crusting, influencing all other properties in this study. The occurrence of a higher number of simulated rainfall would increase the roughness values, altering the hydraulic variables of the runoff in order to reduce sediment transport.