Laboratory and pot experiments were carried out at the University of Agriculture Makurdi to determine the influence of poultry manure on the Phosphate fertilizer need of soybean in some selected Alfisols in Benue State. Surface soil samples (0 – 20 cm) were collected from three locations in Benue State (Daudu, TseKough and Ayange) and Poultry manure sourced from the University of Agriculture Makurdi Livestock Teaching and Research Farm. The physical and chemical properties of the soils and poultry manure were determined using standard procedures. Four (4) Kg of soils were weighed into perforated plastic pots of 5 litres capacity,Six levels of solution P concentrations (0, 0.150, 0.175, 0.20, 0.225, 0.250 mg l-1), 2 levels of poultry manure (0 and 6 t ha-1) and three soils factorially combined constituted the experimental treatments and were arranged in a Completely Randomized Design (CRD) with three replications. Soybean seeds of the variety TGX 1935-3F were planted and grown to maturity. Optimal P solution concentrations for soybeans production on these soils were 0.2 mg l-1for Daudu, 0.225 mg l-1for TseKough while Ayange required 0.175 mg l-1. The amounts of phosphate fertilizer required to achieve this solution concentrations (SPR) were 204 Kg P ha-1 for Daudu, 223.32 kg P ha-1 and 136.55 Kg P ha-1 for TseKough and Ayange respectively. However with the addition of poultry manure the SPR for Daudu was 165.89 kg P ha-1, 185.04 kg P ha-1 for TseKough and 111.03 kg P ha-1 for Ayange representing 18.75 %, 17.14 % and 18.69 % reduction in SPR respectively.
Keywords: Alfisols, Availability, Phosphorus, Poultry manure, Standard phosphate concentration, Standard phosphate requirement
