Carry-over effect of biofertilizers and nitrogen applied to wheat (Triticum aestivum) and direct applied N in maize (Zea mays) in wheat-maize cropping system

A field experiment was conducted at New Delhi during the winter and monsoon season of 1997-99 with wheat (Triticum aestivum L. emend. Fiori & Paol.)-maize (Zea mays L.) cropping system to study the efficacy of 2 biofertilizers [Rhizobacteria (a combination of Proteus vulgaris, Klebsiella planticola and Bacillus subtilis) and Azotobacter] and N in wheat, and their residual effects on succeeding maize. Both the biofertilizers, being at par, recorded significant increase in grain yield and N uptake of wheat as compared to uninoculated control. Similarly, 60 and 120 kg N/ha to wheat resulted in comparable yields but were higher than no N. The N-use efficiency and apparent N recovery were distinctly lower with 120 kg N/ha. Biofertilizer applied to wheat did not cause marked effect on growth and yield attributes, yield, N uptake and N-use parameters in succeeding maize. Nitrogen applied to preceding wheat @ 120 kg N/ha significantly increased all the growth and yield attributes, grain and stover yields, and N uptake in succeeding maize over no N only. However, this treatment (120 kg N/ha) recorded the lowest apparent N recovery in maize. Direct applied N to maize significantly increased the growth and yield attributes, grain and stover yields, and N uptake in maize up to 120 kg/ha. Higher level of 120 kg N/ha to maize recorded lower N-use efficiency and apparent N recovery but higher nitrogen harvest index as compared to lower level of 60 kg N/ha.