Pasture organic management using thermopotassium and thermophosphate in the Cerrado region

Abstract

The objective of this work was to evaluate the performance of the thermopotassium and thermophosphate agrominerals, as sources of P and K, in an organic pasture consortium of 'Marandu' Urochloa brizantha + Stylosanthes spp. in the Brazilian Cerrado. The organic management was compared with conventional farming using chemical fertilizers, during three years, in two adjacent experiments, one with and the other without previous growth of green manure (Crotalaria juncea). The management treatments were: conventional, with the application of 200 kg ha^-1 potassium chloride, 260 kg ha^-1 triple superphosphate, and 217 kg ha^-1 urea; organic, with the application of 1.0 Mg ha^-1 thermophosphate, 2.0 Mg ha^-1 termopotassium, and 7.0 Mg ha^-1 chicken manure; and control, without fertilizers. Soil fertility, dry mass production, and legume content in the pasture were evaluated. The experiment with green manure resulted in a significant increase in the soil-extractable contents of P and K and in pasture productivity. In the organic treatment, due to the slow release of agromineral nutrients, long-term effects are observed on the soil-extractable contents of P and K.