Superphosphate and rock phosphates as phosphorus sources for grass-clover pasture on a limed acid soil in southern brazil

The native pastures of Rio Grande do Sul, Southern Brazil, have low productivity because of summer and spring species growing seasons on low fertility soils. The objective of this research was to evaluate sources of phosphorus (P) and lime rates surface applied on natural pasture for exotic cold season forages species introduction. The results showed that the rock phosphates Gafsa and Arad were efficient sources of Pin moderate to high soil acidity. The soil acidity attenuation by liming increased the forage production and the efficiency of the soluble superphosphate, but reduced the performance of rock phosphates. The surface liming was effective in neutralizing exchangeable aluminum only in the topsoil layers.