Phosphorus sources and gypsum in a mixed pasture grown in a Dark Red Latosol

Abstract

A field experiment to study the effects of phosphorus and gypsum sources in a mixed pasture was carried out at the Animal Husbandry Experimental Station located in Colina, State of São Paulo, Brazil. The pasture had pangolagrass mixed with siratro, perennial soybean and centro. The soil was a Dark Red Latosol (Oxisol). A factorial experiment was used, with phosphorus sources x gypsum (5x2), with the ten treatments assigned in a randomized complete block design, with four replications. Phosphorus sources were: no phosphorus fertilization (Control), triple superphosphate (44% P₂O₅), Araxa rock phosphate (28% P₂O₅), Alvorada rock phosphate (28% P₂O₅), and Patos rock phosphate (18% P₂O₅). Gypsum was the by product of the fertilizer industry and contained 15% S. Thirteen harvests were done in the four years of experimentation. The results evidenced that: a) triple superphosphate had a beneficial effect on the legumes dry matter yield m the first year whereas the other sources had such effect on the fourth year; b) gypsum application significantly increased S percentage in the legumes (first year), proportion of the legumes in the pasture (second year), and legumes dry matter yield (fourth year); c) phosphate application significantly increased P percentage in the grass in all experimental years; d) legumes proportion in the pasture was higher in phosphate fertilized plots than in the Control., after the first year of experimentation.