Influences of Some Preceding Winter Crops and Nitrogen Fertilizer Rates on Yield and Quality of Intercropped Maize with Cowpea

A field study was conducted in Mallawi Agricultural Experiments and Research Station, Agricultural Research Center (ARC), El-Minia governorate, Egypt to decrease mineral nitrogen (N) inputs of maize with good yield quality and increase farmers' benefit. Local maize cultivar T.W.C. 310 was grown under intercropping and sole cultures in one row/ridge that received three mineral N fertilizer rates (75, 87.5 and 100% of the recommended N rate of maize), while local cultivar of cowpea seeds Keraim – 1 were drilled in one row and two rows/ridge under intercropping and sole cultures, respectively. A split split plot design with three replicates was used. Quality of maize grains was tested in the laboratories of Seed Technology Research Department, Field Crops Research Institute, ARC. Maize grain yield and its attributes were increased after harvest of legume crops compared to those grown after wheat harvest. Intercropping cowpea with maize increased grain yields per plant and per ha by 4.00 and 1.94%, respectively, in comparison with sole culture in addition to yielding 16.85 ton/ha of cowpea forage. Cowpea improved yield quality and N use efficiency (NUE) of intercropped maize after berseem cutting. Land equivalent ratio and land equivalent coefficient values for intercrops were much greater than 1.00 and 0.25, respectively, indicating less land requirements of intercropping system than sole maize. Farmer's benefit was achieved by intercropping cowpea with maize that received 87.5% of the recommended mineral N fertilizer rate of maize after berseem cutting.