Erosão em entressulcos e parâmetros de rugosidade vegetal em área de pastagem

Abstract

The Brazilian region known as Brejo Paraibano, in recent decades has been undergoing a process of replacing its native coverage by crops, mainly for pasture for extensive livestock farm, which has favored the occurrence of soil degradation in the form of water erosion. Given this context, this study aimed to quantify the rates of interrill erosion under simulated rainfall and evaluate the roughness parameters vegetable emerged to laminar flow in a pasture area hilly relief. The experiment was conducted in a completely randomized design with 4 treatments, 15%, 25%, 35% and 45% slope in a Ultisol under pasture, 5 replications, totaling 20 plots. The mean flow velocity and infiltration rates of pasture varied significantly with increasing slope contributing to increased erosion rates up to 35%. In the condition of 45% slope was not the greatest soil losses have occurred because of the removal of the horizon, in which the erosion process is acting on the argilic B horizon. The vegetation drag coefficient to pasture expressed elevation when there was a decrease of turbulent flow between plants. In the condition height flow increase, there was a greater energy flow between the mass of water and the plants structure of Brachiaria decumbens that resulted in decreasing on the force drag tension of plants.