Compactação do solo e o impacto na variação espacial de atributos físico-hídricos e produtividade da soja

Abstract

Crop productivity is influenced by physical-water soil attributes such as the available water capacity, density, porosity and stability of the aggregates, serving as indicators of their compaction status. The study area of 25 hectares is located in the Capim Branco Experimental Farm, belonging to the Federal University of Uberlândia, in Uberlândia-MG. The plot is cultivated under no-tillage under dryland, in the soybean-corn/sorghum succession. The objective of this study was to evaluate the impact that soil compaction has on the spatial variation of physical-water soil attributes and on soybean productivity. A grid of 2 points per hectare was defined in the plot. Data were obtained for the physical-water attributes of the soil, density, macro and microporos, total porosity, stability of the aggregates, texture, organic matter content of the soil, Field capacity, permanent withering point and water capacity available at depths of 0-0.2 m. At the same depths and locations information of penetration resistance was raised, with use of a penetrometer. The soybean productivity was determined in the same 50 points of the grid considering useful parcels of 10 m2. The attributer productivity, organic matter of the soil (MOS), clay, sand, density, resistance to penetration (RP), total porosity, microporos, field capacity, permanent wilting point and available water content (CAD) and aggregates and in classes 1-0,5mm and 05-0,25mm, presented mean coefficient of variation (CV); the other attributes were obtained high CV. Spatial dependence was observed in all the studied attributes, being the largest range for the aggregates in class 1-0,5mm (420M) and the smallest for available water capacity (47m) It was concluded that soil compaction decreases total porosity, increasing density and providing less water infiltration and retention, resulting in reduced soybean productivity.