Influence of nitrogen and phosphorus fertilization on yield, sprouting and tillering of marandu grass (<em>Brachiaria brizantha</em> [Hochst] Stapf cv. Marandu)

Abstract

The experiment was carried out from October/1997 to March/1998 with the objective of evaluating the regrowth (R), total dry matter production (TDMP), leaf dry matter production (LDMP) and tillering of marandu grass (Brachiaria brizantha [Hochst] Stapf. cv. marandu). The experimental design in radomized blocks was used in a 4x5 factorial, being four levels of nitrogen (0; 200; 400 and 600 kg/ha of N), and five levels of phosphorus (0; 50; 100; 150 and 200 kg/ha of P₂O₅, with three replicates. For the evaluations, four cuttings of vegetative material were performed at 15 cm above the soil. For DMP, LDMP and R, the analysis indicated (p < 0.05) the models Y = 666.261 – 0.00478694N²+ 4.90862N + 0.993367P (R²=0.78), Y = 467.773 – 0.00253047N² + 6.71686N + 4.34730P (R²=0.94) and Y = 429.602 – 0.00420909N² + 5.69694N + 2.95195P (R²=0.91), respectively. Nitrogen and phosphorus showed a significant effect (p < 0,05) on tillering, being represented by equations: Y = 2265, 76 - 5,04220N + 0,0058129N² + 0,967617P (R²=0,68); Y = 52477230,0 - 18244,7N + 20,9667N² + 3360,0P (R²=0,75) and Y = 117600,0 + 43998,7N - 50,7667N² + 6666,67P (R²=0,55), respectively, for number of tillers, live and decapitated tillers. However, in spite of the use of growing levels of P having provided the plants with linear increase of DMP and LDMP, it represented just 5% of the production.