Effect of Phosphorus and Zinc Application on Nutritional Characteristics of Fodder Cowpea (Vigna unguiculata)

An experiment consisting of four phosphorus levels (0, 40, 60 and 80 kg/ha P₂O₅) and five zinc levels (0, 10, 20, 30 and 40 kg/ha ZnSO₄) was laid out in factorial randomized block design to find out the effect on yield and nutritive value of fodder cowpea (Vigna unguiculata). Application of 60 kg/ha phosphorus recorded 27.64 t/ha yield which was 7.50 and 55.6% higher than 40 kg/ha and no phosphorus application, respectively. Application of Zn in the form of ZnSO₄ @ 20 kg/ha increased (P<0.05) the green fodder yield (25.89 t/ha). The successive increase in P level from 0 to 60 kg P₂O₅/ha enhanced CP level significantly (P<0.05) from 15.07 to 17.97%. Zinc application also increased CP content from 15.23 to 17.56% with increase in ZnSO₄ level from 0 to 20 kg/ha. The content of NDF and ADF were not influenced due to application of Zn and P. The interaction effects of P and Zn were found to be significant (P<0.05) with respect to P and Zn concentration. P and Zn content in cowpea fodder showed declining trend at application rate more than 60 kg/ha P₂O₅ and 20 kg/ha ZnSO₄. Therefore, a combination of 60 kg/ha P₂O₅ and 20 kg/ha ZnSO₄ could be applied to obtain better yield and nutritive value of fodder cowpea.