Nutriçao mineral em fósforo, cálcio e magnésio do braquiarao em amostra de latossolo dos Campos de Vertentes sob influência de calagem e fontes de fósforo

The objective of this work was to study the effect of sources and levels of phosphorus (P) and limestone on the content and accumulation of P, calcium (Ca), and magnesium (Mg) by Brachiaria brizantha. The experiment was conducted in a greenhouse in pots with 3 dm(3) of soil using an Oxisol (Latosol) from Campos das Vertentes region (State of Minas Gerais). The experimental design was completely randomized in a 2 x 5 x 4 factorial arrangement with three replications, two phosphorus sources [Triple Superphosphate (TS) and Araxá Rock Phosphate (ARP)], five P levels (50, 150, 300, 500, and 700 mg P/dm3 soil), and four limestone levels (0, 1/2, 1, and 2 times the level necessary to elevate the base saturation to 50 percent, with level one corresponding to 1.6 t/ha of lime). Five cuttings of plant growth were made during a 243-day period after emergence. The P, Ca, and Mg mineral nutrition was affected by the interaction among the P sources and limestone. The Ca content of the top growth was little affected by the limestone levels, independent of the P sources used; however, it increased with the level of P applied. The Mg content of the top growth increased with limestone level, independent of the P sources used.(RA)