Low soil phosphorus availability triggers maize growth stage specific rhizosphere processes leading to mineralization of organic P

Aims: In this study, we examine the rhizosphere processes influencing organic P (P_o) utilization in soil with low inorganic P (P_i) availability and how they change with plant development. Interactions between plants and the rhizosphere microbial community triggered by P deficiency may provide insights into the role of P availability on degradation of soil organic matter (SOM). Methods: Maize (Zea mays) plants were grown in low P containing soil. Soil pH, potential acid phosphatase activities, soil C and P pools, microbial biomass C and P, microbial community structure, and plant P content were analyzed at different vegetative growth stages (VGS). Results: At early VGS, the plants were P deficient which correlated with greater rhizosphere potential acid phosphatase activity, degradation of SOM and a reduction in the P_o pool. At late VGS, the plants appeared to recover which correlated with a decrease in Meh (III) extractable P, an increase in microbial biomass C and P, change in microbial community structure, and greater total P (TP) in the plant biomass. Conclusions: The mineralization of organic C and P_o are coupled in low P soil where N is not limited. The overall findings from this study advance our understanding of the coupled biogeochemical rhizosphere processes controlling P cycling at different plant growth stages and notably the importance of P_o to the overall P needs of plants in soil with low P_i availability.