Abstract

ROMERO, Carlos; ALFONZO, Silvestre; MEDINA, Rosa  and  FLORES, Ramón. Initial evaluation of fertilization with rock phosphate in three species of the Brachiaria genus. Zootecnia Trop. [online]. 2003, vol.21, n.2, pp.183-196. ISSN 0798-7269.

An experiment was carried out in Yaracal Municipality Cacique Manaure, State Falcon, to measure the effect of the fertilization with four phosphorus levels (0 [control], 50, 100 and 200 kg P₂O₅/ha, on the biomass (DM production), height and relationship leaf/tiller(L/T) of Brachiaria humidicola, B. decumbens and B. brizantha. The soil used shows a franc-oozy texture, acid pH and very low phosphorus content. A block design was used in with sub-divided plots; main plots: phosphorus, sub-plots: species and sub sub-plots: cut date. The phosphoric source comes from: phosphate rock coming found in Riecito. The fertilization was completed with 100 kg N/ha and 100 kg K₂O/ha. Four cuts were carried out to the fourth and sixth week of the regrowth. The DM in P1, P2 and P3 was similar, but it registered significant differences (P<0.01) with the control (P1:2116, P2:2233, P3:2404 vs P0:1544 kg DM/ha/cut to the fourth week and P1:3495, P2:3744, P3:4107 vs P0:2,551 kg DM/ha/cut to the sixth week). The B. humidicola was superior (P<0,01) to that of B. brizantha and B. decumbens (2384, 1945 and 1895 kg DM/ha/cut respectively to the fourth week and 3919, 3246 and 3261 kg DM/ha/cut to the sixth week). Likewise the cut date affected significantly (P<0.01) the DM. The height presented a similar behavior to the DM and the relationship L/T it diminished significantly (P<0.05) with the treatments with fertilization in relation to the control. In conclusion, the amount of phosphorus content in the fertilizer did not show a significant effect, the differences within the control are attributable mainly to the effect of the nitrogen content.

Keywords : Production of biomass; phosphorus; phosphate rock; Brachiaria humidicola; Brachiaria brizantha; Brachiaria decumbens.