NUTRIENT USE EFFICIENCY OF SOYBEAN AS AFFECTED BY PHOSPHORUS FERTILIZATION IN THE SOUTHERN GUINEA SAVANNA OF NIGERIA

Abstract

The study was carried out at Teaching and Research Farm of the Federal University of Technology Minna to determine the effect of Phosphorous fertilization on the agronomic nutrient use efficiency (ANE) and partial factor of productivity (PFP) of P in soybean production. The treatments consisted of five P rates (0, 15, 30, 45, and 60 kg ha^-1), these were factorially arranged and laid out in a randomized complete block design (RCBD) with three replicates. Physicochemical properties of soil of the experimental site was assessed using a standard procedure described by IOAC. The result of soil analysis revealed that, soil of the study site was dominated by sand with slightly acidic reaction. The result further showed that, soil organic carbon was low while available P was moderate. There was response to P with the highest grain yield of 857 kg ha^-1 obtained from soybean fertilized with 45 kg P^-1. The efficiency of applied nutrients in increasing grain or biomass yield (ANE) and increase in yield pertaining to an increase in only a single specific nutrient applied (PFP) were significantly affected by P fertilization and their values were significantly reduced as the P rate increased. Application of 15 kg P ha^-1 had the highest ANE and PFP values of 9 kg grain kg P^-1 and 42 kg grain kg P^-1respectively. Phosphorus fertilizer may be applied at rate of 15 kg ha^-1 for economic and profitable yields and for efficient use of P to minimize environmental pollution by P. In conclusion, Phosphorus was more efficiently used by soybean at lower rate compared to a higher rate as indicated by ANE and PFP.  The study recommends Lower rate of P should be applied for higher P use efficiency. Phosphorus fertilizer should be applied at the rate of 15 kg ha-1 for economic and profitable yields of soybean.