Critical levels of phosphorus for the establishment of pasture grasses on a Red Yellow Latosol. I: greenhouse test

Abstract

The objectives of the present study, carried out in a greenhouse, were to determine the critical levels of soil P, by the Mehlich I and Resin extractors, and in the plant, for the stablishment of pastures of Brachiaría decumbens Stapf., Brachiaría brizaníha (Ilochst.) Stapf cv. Marandu and Panicum maximum JACK., on a Red Yellow Latosol. The experimental design was a randomized complete block with four replications and 21 treatments (7 levels of P x 3 species). The levels of P were: 0; 17.5; 35.0; 70.0; 140.0; 280.0 and 560.0 ppm. Two shoot cuts of plants were done: the first, fifty days after sowing and the second, thirty days later. No differences in P requeriment for crop establishment were observed among the species, for 80% of maximum growth. The critical level of soil P, in the first cut, varied from 8.0 to 12.0 ppm (Mehlich I) and 13.0 to 18.0 ppm (Resin); for the second, cut, the levels were 11.5; 12.0 and 14.0 ppm (Mehlich I) and 18.0; 22.0 and 24.0 ppm (Resin), for the Brachiaria decumbens, Brachiaria brizaníha and Panicum maximum, respectively. The critical levels of P in the plant were, in the same order, 0.11; 0.13 and 0.12% for the first cut and 0.09; 0.12 and 0.10%, for the second cut.