Effect of optimal and suboptimal nitrogen application on nitrogen content, uptake and use efficiency by wheat in different crop establishment methods, Zn fertilization and microbial inoculation options

To address the significance of cost-effectiveness and environmental concerns of nitrogen nutrition a field experiment was conducted at ICAR-Indian Agricultural Research Institute, New Delhi. The major objective of the study was to know the effect of different crop establishment methods (CEMs), sources, and rates of N application on the concentration, uptake, and efficiency of applied N. The combination consisted of two microbial consortia (MC) Anabaena sp. (CR1) + Providencia sp. (PR3) consortia (MC1) and Anabaena-Pseudomonas biofilm formulations (MC2) were applied with a 75% recommended dose of nutrient (RDN). These microbial inoculations were compared with RDN (120 kg N ha(-1) and 25.8 kg P ha(-1)), 75% RDN, and control. All the treatments were applied with and without zinc (Zn) (soil application of 5 kg Zn ha(-1)) in a split-plot design with three replications. The order of significance of treatments in enhancing the grain N concentration and total N uptake was the rate of nutrient application (RDN)> CEMs > Zn fertilization > microbial consortia. The contribution of these factors to the increase in total N uptake was 23.8-61.6, 26.5-28.5, 21.1-23.7, and 18.0-20.2 kg ha(-1), respectively. Considering the contribution of microbial inoculation to N concentration and uptake and the positive correlation between them, they have contributed significantly to nutrient endowments along with improvement in wheat yield. In nutshell, our study concludes that the most promising combination for nitrogen nutrition in our experiment was 75% RDN + MC2 + Zn.