Productivity of Marandu grass as a function of liming and phosphate fertilization in a Typic Hapludult from Amazonia

Abstract

Little information is available concerning liming and phosphate fertilization for grassland maintenance in Amazonia. The dry-weight yield of Brachiaria brizantha was assessed over three harvest periods as a function of top-dressing with lime and phosphorus. The experimental design consisted of fully randomized blocks with four replicates arranged in subdivided plots according to the sampling season (plots), phosphorus application rate (0, 30 and 60 kg ha–1 P2O5) (subplots) and presence or absence of liming (sub-subplots). The grass was harvested by cutting 25 cm above the soil level, and the 0- to 5-, 5- to 10-, 10- to 20- and 20- to 40-cm soil layers were sampled 3, 9 and 13 months after liming. Top-dressing with phosphorus and lime had no effect on the dry-weight yield, nutrient uptake or crude-protein percentage of the Brachiaria brizantha shoots. However, phosphorus and lime treatment reduced the soil acidity and increased the calcium, magnesium and phosphorus levels in the upper soil layers.