Effect of phosphorus and starter nitrogen on cowpea (Vigna Unguiculata l. Walp) performance in southern Guinea savanna of Nigeria

Abstract

Cowpea (Vigna unguiculata L. Walp) is an important grain legume that plays critical roles in diets of millions of people in Africa and other parts of the world. A pot experiment was conducted in 2016 at the screen house of School of Agriculture and Agricultural Technology, Federal University of Technology, Minna to determine the effect of phosphorus and starter nitrogen(N) on cowpea, sampea 15 (IT99K-573-2-1) performance in Minna, Nigeria. Experimental soils were collected from the Teaching and Research farm of the same institution. The treatments consisted of five rates of P application (0Kg P ha-1, 10Kg P ha-1, 20Kg P ha-1, 30Kg P ha-1 and 40Kg P ha-1) and four rates of N application (0Kg N ha-1, 10Kg N ha-1, 20Kg N ha-1 and 30Kg N ha-1 ). The treatments were laid down in a completely randomized design and replicated four times. The results showed that the textural class of the soil was sandy loam, soil reaction was slightly acidic (pH=6.5), low in organic carbon (4.22g kg-1). Available P (6 mg Kg-1) and high Total N (0.56g Kg -1). The effect of starter N on plant height, number of leaves, days to flowering and podding, grain and haulms yield was not significant (P>0.05). Application of 10 Kg P ha-1 significantly (P>0.05) improved plant height, pods per plant, grain per pod, grains and haulms yield. The interaction between P and starter N was not significant (P>0.05) on all parameters measured except on number of days to flowering and fresh haulms yield. Application of 10 Kg P ha-1 is therefore recommended as optimum for the cowpea variety assessed.