SOIL AND PASTURE WATER STATUS IN A LONG TERM INTEGRATED CROP-LIVESTOCK SYSTEM PERSPECTIVE

Resumo

Integrated crop-livestock systems have been indicated as alternatives to intensify land use. However, the soil water dynamics for proper water resources management is still poorly understood in such systems. This study aimed to assess the impact of grazing intensities on soil and black oat plants water status in a long-term, no-tillage, integrated soybean-beef cattle system. The experiment has been carried out since 2001 with a soybean and cattle grazing on black oat + ryegrass pasture succession. Treatments consist of different grazing intensities regulated by the pasture sward height, namely: intensive grazing (10 cm sward height), moderate grazing (20 cm sward height) and non-grazed. Soil bulk density was determined after soybean harvest. Soil moisture and water status of the black oat plants were monitored from the pasture sowing until the animal removal from the area, by the evaluation of leaf temperature and water potential. Grazing season begins with similar surface soil bulk density among the evaluated systems. The intensive grazing store less water in the soil profile, with greatest water stress degree of black oat plants along the evaluated period. The proper grazing management (moderate intensity) allowed black oat plants to keep leaf temperature and water potential similar to non-grazed condition, regardless of differences in soil moisture.