Response to phosphorus applied in rainy-season crop and nitrogen applied to wheat (Triticum aestivum) under sorghum (Sorghum bicolor)/cowpea (Vigna unguiculatd)-wheat cropping system

The results of 2 years field experiment showed that fodder yield nitrogen and phosphorus uptake in the rainy-season crops increased favourably up to 30 kg P₂O₅/ha while grain yield responded up to 60 kg P₂O₅/ha. Wheat (Triticum aestivum L. emend. Fiori & Paol.) preceded by sorghum [Soghum bicolor (L.) Moench] + cowpea [Vigna unguiculata (L.) Walp.] fodder (F), followed by cowpea grain straw incorporation (SI) performed better than grown after sorghum (F). Both these cropping systems contributed 26.38 and 28.62 kg N/ha, respectively, resulting in an increase in wheat yield than sorghum (F)-wheat system. Residual effect of phosphorus (applied to rainy-season crops @ 30 and 60 kg P₂O₅/ha) increased grain yield of succeeding wheat by 7.53 and 10.13%, respectively, over no phosphorus and also favourably influenced N and P uptake. Grain yield of wheat increased by 26.96 and 32.71% higher at 75 and 150 kg N/ha, respectively over the control, while N and P uptake responded only up to 75 kg N/ha.