Qualidade física de um latossolo vermelho distroférrico sob integração lavoura-pecuária.

Abstract

The crop-livestock integration can be defined as the temporary rotation, in the same area, of grain crops and pastures with livestock. This system has attracted interest of farmers in grain-producing regions. In southern Brazil, this practice is based on the sowing of winter forage for grazing cattle in rotation with summer crops. Studies show that cattle trampling compacts the soil, while others show that with proper stocking, suspension of grazing in wet soil conditions and maintenance of adequate soil cover, there is no negative influence on yield of summer crops. The experimental area has a system of crop-livestock integration implemented in 2002 in an area of 8 ha, at the Experimental Farm COAMO - Cooperativa Agroindustrial, in Campo Mourão, Paraná, in which the treatments are made of different height levels of forage grazing where the management of animals kept grazing heights of ryegrass and oats in 7, 14, 21 and 28 cm and a treatment where no grazing. The objectives of this study were to evaluate some physical properties of soil for comparison of different management systems in the supply of winter forage. In order to verify whether the animal trampling reduces soil physical quality to evaluate the soil physical quality the least limiting water range (LLWR) was quantified as a modern indicator of soil physical quality quality. An alternantive methology also was evaluated to obtain the LLWR faster and using the critical soil density (Soil bulk density in which IHO = 0) for monitoring of soil physical quality. The bulk density and macroporosity are indicative of basic soil physical quality, which were measured over five years for monitoring the soil physical quality. The treatments reduced the LLWR due to grazing height with increased soil bulk density associated to the impact of animal trampling. The alternative methodology for LLWR evaluation was accurate and appropriate for LLWR quantification. It was found that the soil bulk density and macroporosity both are dependent on management practices used in integrated crop livestock. To maintain a appropriate soil physical quality the forage managemente should be done to maintain the grazing height equal or above 21cm.