Phosphorus horizontal and vertical distribution in single soybean crop and in integrated crop-livestock-forest systems

The objective of this work was to evaluate the horizontal and vertical distribution of soil phosphorus and soybean yield in single-crop and in integrated crop-livestock-forest (ICLF) systems. The evaluated treatments were: forest planted with eucalyptus; soybean crop and off-season corn intercropped with Urochloa brizantha 'Marandu'; U. brizantha pasture; ICLF system; and two control areas, with native forest and fallow. Soil samples were taken at the depths of 0-5, 5-10, 10-20, 20-30 cm for determining chemical characteristics. Evaluations were done in the second crop year after the implementation of the experiment. In the ICLF system, soil and yield were evaluated in four equidistant transects, at the center of the tree rows, and at 3, 6, 10, and 15 m from the rows on the northern and southern sides. Available P levels (Mehlich-1) were greater at the upper soil layers, in the systems with soybean/off-season corn and ICLF. In ICLF, available P contents did not differ between the distances from the tree rows, and soybean yield did not differ from the one observed in the soybean/off-season corn system. Therefore, a two-year ICLF is not yet capable of major interference on soil chemical characteristics and on soybean yield.