Effect of phosphorus fertilization and microbial inoculants on yield, phosphorus use-efficiency and available phosphorus in maize (Zea mays)- wheat (Triticum aestivum) cropping system

Abstract

A field experiment was conducted between 2012-14 to investigate the effect of different phosphorus levels (control-no P, 33% P, 50% P, 100% P and 100% P in 3-splits of the recommended dose of P) and microbial inoculants (un-inoculated control, arbuscular mycorrhizal fungi, AM phosphate solubilising bacteria, PSB and AM+PSB) in maize-wheat system. The study revealed that the maize and wheat grain yields were increased by 20% and 40%, respectively, under 100% P which were significantly higher over control. The total P uptake by maize and wheat varies from 11.7–20.7 kg/ha and 17.7–32.4 kg/ha, respectively. The highest apparent recovery (AR) in both the crops was recorded when 50% P was added with AM+PSB inoculation whereas, a significant reduction in AR was recorded with increase in fertilizer P beyond 50% of recommended P. Agronomic efficiency was highest under 50% P averaged across microbial inoculants in both maize (32.5 kg grain/kg P) and wheat (78.5 kg grain/kg P). Grain yield of both maize and wheat was significantly and positively correlated with Olsen P content at tasseling (r = 0.30*) and panicle emergence (r = 0.35**). The higher P use-efficiency under 50% recommended P along with microbial inoculants suggests applying lower doses of P fertilizer along with microbial inoculants to achieve optimum yield in maize-wheat system without any adverse impact on soil fertility.