Erosão hídrica e infiltração de água no solo em sistemas de cultivo, sob chuva simulada

Abstract

Inadequate soil management practices associated with bare soil are the main factors that promote hidric erosion in tropical countries such as Brazil. In this study were evaluated soil and water losses, vegetation index, water infiltration into the soil and the adjusted Kostiakov-Lewis, Horton and Philip models to estimate soil water infiltration rate in four cropping systems on a Red Ultisol. The systems studied were exposed or bare soil (SE), soybeans grown under conventional tillage (PC), soybean grown under no-tillage (NT) and established pasture without cattle trampling (PA) in six seasons. Every 20 days after the soybean´s sowing digital photographs were taken to estimate soil coverage ratio. Also, simulated rainfall at the parcels was measured using a portable sprinkler infiltrometer (InfiAsper) calibrated to apply intensity of rainfall of 60 mm h-1. Soil losses ranged from 3.10 to 11.40 and 0.03 to 0.19 Mg ha-1 h-1 in the SE and PA, while water oscillated from 300.60 to 555 and 62.8 to 229.4 m3 ha-1 h-1 in the SE and PD, respectively. Soil losses decreased with increasing vegetation cover ratio, which at the PA had a maximum value of 98.1%. The initial effect of soil under conventional tillage in cropping systems is temporary, which makes them susceptible to erosion. The models were adjusted using the volume of water that was infiltrated during the corresponding time interval. In the PD system was obtained the highest infiltration rate (TIE). There was no difference between the SE and PC TIE. The best fit found is for the Horton´s model in systems with vegetal cover and without soil tillage.