Microbial consortium increases maize productivity and reduces grain phosphorus concentration under field conditions

The use of microbes that improve plant phosphorus (P) use efficiency is an avenue to boost crop yields while alleviating environmental impacts. We tested three microbial inoculants (Rhizoglomus irregulare alone - designated AMF; Pseudomonas putida alone - designated PSB; and R. irregulare and P. putida in consortium - designated AMF+PSB), combined with chemical fertilizers, in an intensive maize agricultural system.

As hypothesized: (i) despite the native soil microbial community and the application of P fertilizer, the microbial inoculants enhanced plant P uptake from the soil by 14-60%, and consequently improved P acquisition efficiency; (ii) PSB and AMF+PSB plants produced ±50% more biomass per unit of P taken up, and consequently enhanced plant internal P use efficiency (i.e. the biomass produced per unit of P); and (iii) the combined inoculation of AMF and PSB provided the best results in terms of productivity and P use efficiency. Further, the microbial inoculants altered P allocation within the plant, reducing grain P concentration.

By testing the microbial inoculants under field conditions, our study clearly shows that the microbial consortium (AMF+PSB) increased maize productivity, and at the same time improved P use efficiency. Further, the use of these microbial inoculants was shown to be compatible with conventional agricultural management practices.