Abstract

Flexible phosphorus (P) fertilizer rate recommendation could be based on variations in soil characteristics that affect yield responses. Experiments were conducted in the Department of Agronomy, LAUTECH, on the effects of P rates on maize and P sources on cowpea in four soil types. On average, soil types and P rates influenced maize height and grain yield. Iwo and Egbeda soils supported taller plants than Itagunmodi soil. Phosphorus fertilization enhanced height and grain yield compared with no P. To optimize maize grain yield for Itagunmodi and Egbeda soils, application of 15 kg P₂O₅ ha^-1 was sufficient while for Majeroku and Iwo, it was 30 and 75 kg P₂O₅ ha^-1, respectively. Cowpea grain yield and P uptake were significantly affected by soil types and P sources. Iwo and Egbeda soils supported higher grain weights and P uptake than Itagunmodi and Majeroku soils. Triple super phosphate (TSP) and no P supported higher grain weights and P uptake than rock phosphate (RP) and single super phosphate (SSP).

Key words: Cowpea, maize, phosphorus fertilization, phosphorus uptake, soil types, southwestern Nigeria.

Abbreviation

SSP, Single super phosphate; TSP, triple super phosphate; RP, rock phosphate; WAP, weeks after planting.