Estabelecimento de leguminosas e atributos físicos, químicos e biológicos do solo sob influência de diferentes manejos de pastejo em Igarapé-açu, Estado do Pará.

Abstract

In Oriental Amazonia, the growing demand for improvements in productivity and competitiveness in the agricultural sector, the production of low costs supplements, among which are legumes intercropped with grass, is a major step for the development of animal production systems. The main expectation of the use of legumes is the improvement of animal production compared to grass pasture exclusively. The effects of animal distribution and days of grazing rest, are also crucial to maintain the sustainability of livestock production system. Information about its effects on physical, chemical and microbial biomass quality of pastures soil are still rare. The objective of this study was to evaluate the influence of different catle distribution and different days of grazing rest , about the establishment of legumes Flemingia macrophylla and Cratilia argentea, on the physical, chemical and biological attributes of yellow claysoil under a already established pasture of Brachiaria brizantha cv. Marandu, located in Igarapé-Acu, Northeast of Para in function of grazing systems with different animal allotment rate and resting days of the pasture (SPl= 1UA/ha and 56 resting days; SP2= 0,7UA/ha and 28 resting days; SP3= 0,7UA/ha and 56 resting days) and four seasons to sampling (April/2007 — rainy weather; October/2007 — dry weather; April/2008 — rainy weather; October/2008 — dry weather), in the layers 0-10, 10-20, 20-40, 40-60 cm for evaluation of the physical attributes and in the 0-10, 10-20, 20-50 cm for the chemical ones. The biological attributes, were evaluated just in the depth of 0-10 cm. The experimental outlining was blocks by chance with three repetition. The treatment, conform the variable to be evaluated, were distributed in quotas sub and subdivided. Singly, the grazing systems influenced the studied variable. It follows that the handling systems used, did not influenced on the legumes establishment, on the physical and chemical attribute, and on the carbon and nitrogen from the microbial soil biomass though, they showed significant differences on the sample soil depth and on the seasons evaluated.