THE EFFECT OF ZINC RATE AND PLACEMENT ON YIELD AND ZINC UTILIZATION BY BLACKBEAN (Phaseolus vulgaris var. Black Turtle)

Growth chamber experiments were conducted to investigate the effect of size of fertilizer reaction zone, rate of added zinc and method of placement of added zinc on the dry matter yield, zinc concentration and zinc uptake of blackbeans grown on a calcareous soil. Relationships between zinc concentrations in the plant, zinc utilization by the plant and zinc concentration in the soil reaction zone were obtained. An equation was developed relating zinc utilization to zinc concentration in the fertilizer band, and a figure was derived showing how increasing the size of the fertilizer zone impacts upon the zinc concentration of the plant. The results indicate that inorganic zinc fertilizers must be mixed as uniformly as possible for maximum effectiveness. Key words: Zinc, placement, calcareous, soil, blackbean, Phaseolis vulgaris