Caracterização físico-hídrica dos solos da bacia do Córrego Marinheiro, Sete Lagoas MG

Abstract

Soils make up an important part of the hydrological cycle, either by storing the water or by conducting its flow. On the other hand, the understanding of water behavior in different types of soil depends on the characterization of hydraulic parameters that are difficult to obtain. The physical-hydriccharacterization, based on work with a variety of methods of analysis, allows measuringthe soilporous matrix. The knowledge of the physical-hydric parameters is fundamental to the elaboration of irrigation and drainage projects, to produce water balance models and to understand the processes of pedogenesis, leaching and plant nutrition. The soils of the Marinheiro creek watershed were chosen due to the presence of soil degradation foci, with potential impacts on water resources. When they are combined with the environmental pressures of urbanization and agricultural practices around the basin, there is great concern for conservation of these resources. This work aimed to characterize the physical-hydric parameters of different soil classes representative of the watershed. For this purpose, the saturated hydraulic conductivity (K0), and the available water capacity of the plants (CAD) were measured. Soil water retention curves were modeled for 10 soil classes (PVA, LV, CY, CX, CH, PA, TC and NV) at two sampling depths: 20 cm and 50 cm. In addition, soil physical parameters were characterized and analyzed statistically in order to apply, to elaborate, and to adjust pedotransfer functions capable of estimating K0 and CAD. For the determination of K0, infiltration tests by Guelph permeameter were performed by applying two sequential hydraulic loads - 5 cm and 10 cm head. To determine the retention curves, undeformed samples of 5 x 5 cm volumetric rings were collected to determine the highest potentials in the sandbox (-1, -2, -4, -6, -10, -33 and -66 kPa) and deformed samples were collected for determination of lower potentials in the Richards pressure plate apparatus(-500 and -1500 kPa) and in the WP4C psychrometer. The highest estimated values of K0 were observed for the LV and the CH classes. The highest CAD values were observed in the PVA, CY, CX and NV classes. Some models proposed for CAD presented a good predictive capacity, unlike the FPTs elaborated to predict K0.