Qualidade química e física do solo sob vegetação arbórea nativa e pastagens no pantanal Sul-Mato-Grossense

Abstract

The search for improved productivity of livestock has stimulated deforestation of forested areas in the Pantanal for pasture planting, raising concerns about the sustainability of the natural resources. To study some aspects of land use in the Pantanal of Mato Grosso, Brazil, this study aimed to evaluate the changes in chemical and physical soil properties due to the conversion of native tree vegetation in pasture, and the exposure of native pasture to a continuous grazing system. The environments of the study consisted of three remnants of native vegetation, represented by a semi-deciduous forest (NF) and two Cerrado (CE1 and CE2) areas, three 27, 26 and 11-year-old Brachiaria decumbens pastures, planted to replace FN , CE1 and CE2, respectively, and a native pasture with predominance of Mesosetum chaseae and Axonopus purpusii, under three different grazing systems (continuous and ungrazed for 3 and 19 years). Disturbed and undisturbed soil samples were collected from each study environment, in the layers 0–10 and 10–20 cm, with three replications. The replacement of native tree vegetation by pasture and by continuous grazing of native pasture resulted in a reduction of the soil chemical quality, evidenced primarily by a loss of soil organic matter, particularly in the layer 0–10 cm. Although the soil physical quality also tends to decrease under cultivated and native pasture under continuous grazing, the values of bulk density, total porosity, macroporosity, microporosity, hydraulic conductivity of saturated soil and soil penetration resistance did not reach levels considered critical for root development.