EFFECT OF PHOSPHORUS FERTILIZATION ON SELECTED SOIL PROPERTIES AND SOYBEAN PERFORMANCE IN SOUTHERN GUINEA SAVANNA OF NIGERIA

One of the limiting factors in soybean production is low native soil phosphorus (P) availability and poor utilization efficiency of added P. Phosphorus fertilization could increase soybean yields. The study determined the effect of P fertilization on soil organic carbon (SOC) and available P contents, and yield attributes of soybean. The treatments were five P rates; 0, 15, 30, 45, and 60 kg ha-1. The experimental design was a randomized complete block design with three replicates. Soil of the study site was dominated by sand with slightly acidic reaction. Soil organic carbon was low, while available P was moderate. Soil organic carbon and available phosphorus were significantly reduced by P fertilization by as much as 50 % and 70 % respectively. There was response to P fertilization by soybean. Biomass yield was enhanced by application of single super phosphate fertilizer. The highest grain yield and haulm yield of 857 kg ha-1 and 1436 kg ha-1 were obtained from soybean fertilized with 45 kg P ha-1. Application of 45 kg P ha-1 increased the grain yield and haulm yield by more than 58 % and 100 % respectively compared to the control.