evaluation of yield and nitrogen use efficiency of maize and cotton intercropping under different nitrogen levels

in order to evaluate the yield and nitrogen use efficiency of corn and cotton intercropping under different levels of nitrogen, an experiment was conducted as a factorial arrangement based on completely randomized block design with three replications. the experimental treatments were nitrogen fertilizers in four levels (0, 50, 100 and 150 kg ha-1) and planting pattern in three levels (maize sole cropping, cotton sole cropping and maize/cotton intercropping). results showed that fertilizer levels and cropping patterns had significant effect on economical and biological yield, nitrogen uptake and nitrogen use efficiency indices in maize and cotton. during growth season nitrogen concentration decreased in maize and cotton. nitrogen uptake and concentration and biomass were enhanced with increased levels of nitrogen in both plants. the highest economical and biological yield of maize and cotton were observed on highest fertilizer level and sole cropping. the ler was up to 1 in all nitrogen levels and with a positive effect of intercropping on plant yield was observed. agronomic nitrogen use efficiency and nitrogen uptake efficiency were significantly reduced with increased nitrogen levels on both plants. nitrogen efficiency was also higher in maize compared with cotton in all of the treatments. ler evaluation for all nitrogen efficiencies showed that nitrogen use and uptake were more efficient in intercropping compared with sole cropping. nitrogen competitive ratio showed that nitrogen uptake ratio was higher with 0, 50 and 100 kg nitrogen ha-1 for maize, while it was higher for cotton with 150 kg ha-1 level.