Caracterização fisica dos solos de uma microbacia degradada em Vera Cruz, SP

AUTOR(ES)
DATA DE PUBLICAÇÃO

1998

RESUMO

The knowledgement of soil physical properties in a catchment basin, in special at places which show signs of erosion and degradation, represent the flfst step for a successful conservation planning as well as to provide additional information for the application of mathematical models that determine the soil erosion potential. This study was carried out to characterize the physical properties of the soil units within a catchment basin and, to evaluate the spatial variability of infiltration rate and thickness of the A horizon, in soil units utilized for agriculture and pasture activities. Soil samples and field measurements were obtained in 1996/97 in the catchment basin in Vera Cruz (SP), according to: regular square grid with 10 meters space, resulting in 25 sampling points at which the saturated rate infiltration and thickness of the A horizon were determined, in dark-red latosol - LE (hapludox) and yellow-red podzolic - PV2 (kandudalf) in: coffee, pasture and natural vegetation; undisturbed soil core samples were collected at 18 points in soil units used for agricultural production. Statistical analysis showed a high variability in the thickness of the A horizon and soil water infiltration. Through the semivariogram it was possible to show the spatial dependence structure for thickness of A horizon in coffee crop in two soils (LE and PV2). This structure was found for soil water infiltration in the transition horizon of PV2, for all crops. Geographical Information System (Idrisi) was utilized to help the choice of sampling places by overlaying soil map and land use, and to show the spatial results. A data base within the GIS/Idrisi was also created to make the thematic maps of bulk density and soil porosity for the A and B horizons. The cross-semivariogram showed positive spatial correlation between thickness and soil water infiltration, in PV2/coffee crop and PV2/natural vegetation. The buIk density for the LE superficial horizon, in pasture and coffee crop, shows positive correlation with soil water infiltration. This fact and the small thickness of the superficial horizon, indicated a intensive degradation process in this soil unit. In PV2 there was larger variation and also decrease of the thickness of the A horizon, in coffee crop and pasture as obtained in natural vegetation. The loss of the A horizon in the areas used for agricultural production is a further indication of the erosion process and the important function of natural vegetation cover in preserving the superficial horizon

ASSUNTO(S)

bacias hidrograficas solos - conservação

ACESSO AO ARTIGO

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