ESTABLISHMENT FERTILIZATION ON Andropogon gayanus CIAT 621 AND Centrosema macrocarpum CIAT 5062ASSOCIATION IN A CHIRIQUI ULTISOL.

Abstract

A study was carried out at Chiriqui, District of David, province of Chiriqui to determine the effect of four dosages of P (0, 50, 100, 150 kg/ha), K (0, 30, 60, 90 kg/ha) and S (0, 20, 40, 60 kg/ha) on A. gayanus CIAT 621 and C. macrocarpum CIAT 5062 association. A San Cristobal design with four repetitions was used. Significant differences P<0.01 were found by establishment fertilization effect on dry matter yield of each of the components and for the total association. The equation Y = 2366.93 + 31.33 P - 0.14 P²; R² = 0.33 (P<0.01). describes the phosphorus effect on A. gayanus dry matter yield. On the other side Y = 310.52 + 1.56 P + 0.025 PK; R² = 0.38 (P<0.01) describes the phosphorus and phosphorus x potassium interaction effect on C. macrocarpum dry matter yield. For the total association A. gayanus + C. macrocarpum phosphorus had a cuadratic response and potassium was linear and their effects on total dry matter yield are given by the equation: Y = 2382.8 + 30.78 P - 0.118 P² + 9.40; R² = 0.42 (P<0.01). There was not effect (P>0.01) of sulfur on grass or legume yield. Level of 50 kg of phosphorus and 30 to 60 kg/ha of potassium are required for a good establishment of A. gayanus and C. macrocarpum association.