Implicações da altura de manejo de pastagem de papuã nas características físicas e químicas de um latossolo vermelho sob sistema de integração lavoura-pecuária

Abstract

Spontaneous occurence of alexandergrass (Urochloa (Syn. Brachiaria) plantaginea) is observed in southern Brazil in the summer. This plant is considered a weed, although it has great potential forage. However, its use as pasture is still little studied, especially in the crop-livestock integration system. This study was performed to evaluate the effect of sward management heights of alexandergrass pasture, with and without cattle trampling, on soil physical and chemical properties, and microbial activity. The study was conducted at the IAPAR Experimental Station, at Pato Branco, Paraná, Brazil. The experimental design was randomized blocks with three replications. The treatments were arranged in a factorial split-plot during the grazing period. The plots received levels of the factor sward management heights of alexander (0.10, 0.20, 0.30 and 0.40 m), while the subplots were established in areas with (grazed by goats) and without cattle trampling (manual cutting). In winter, in succession to grazing, cultivation of wheat was implemented, only in the subplots that have received animal trampling. Have been evaluated the soil bulk density, porosity, macro and microporosity, and soil penetration resistance; the levels of soil organic matter, phosphorus, potassium, calcium, magnesium and aluminum; aluminum saturation, pH and base saturation in samples collected in the layers: 0.00 to 0.05, 0.05 to 0.10, 0.10 to 0.15 and from 0.15 to 0.20 m deep. Were evaluated also the microbial respiration in samples collected in the layer from 0.00 to 0.10 m deep. The data were subjected to analysis of variance, regression testing, and correlation analysis. In general, the height of pasture management in Alexandergrass, in the presence or absence of animal trampling, hasn't significantly affected the soil physical, chemical and biological characteristics, evaluated after the first cycle of treatment application. Effects of trampling were observed on soil porosity, but at levels that did not cause problems for the development of wheat plants grown after grazing. The grain yield of wheat crop was not affected by the height of pasture management of Alexandergrass.