Caracterização do encrostamento superficial do solo cultivado com cafeeiros submetido ao controle de plantas daninhas com herbicida de pré-emergência

Abstract

Soil devoid of vegetation cover are prone to the direct impact of raindrops, resulting in the breakdown of aggregates and clay dispersion that, combined with the infiltrating water, causes the clogging of pores and, consequently, a sealed surface. In this present study, we aimed at characterizing the surface crusting and physical-hydric behavior of a Red Latosol exposed to chemical weed control of coffee crop. The weed control methods evaluated were pre-emergence herbicide (crusted soil), post-emergence herbicide, and with no weeding (no crusted soil). The experimental design was of randomized block, using a 3x2 factorial scheme that represents three control methods and two layers (0-5 and 5-15 cm) with nine replicates. Physical and chemical analysis of the layers were performed. The presence of superficial crusting on the soil was characterized by smaller values of accumulated infiltration and hydraulic conductivity, as well as greater penetration resistance and bulk density. The continuous application of pre-emergence herbicide to Red Latosol resulted in lower surface roughness, an intrinsic pattern of crusted soils. The evaluation of Scanning Electron Microscopy (SEM) images and the mapping of elements from the Energy Dispersive Spectroscopy (EDS) were capable of demonstrating the presence of several minerals and the granular structure of a Latosol, as well as the different patterns of aggregation and porosity. Crust formation on the soil surface influenced the physical-hydric behavior of a Red Latosol exposed to chemical weed control methods in coffee crops. Soil management with preemergence herbicide caused a reduction in the amount of pores with diameter greater than 145 μm, due to the formation of surface crust, which negatively affected the processes of soil drainage and aeration. On the other hand, the increase of available water capacity for an encrusted soil in the sub surface layer denotes a potential to retain more water than the other evaluated treatments.