Impact of Phosphorus Fertilizer and Microbial Inoculants on Maize and Soil Microbiota

Maize (Zea Mays) is an important crop that strongly depends on soil phosphorus availability. Therefore, this study aimed to assess the compatibility of two commercial microbial inoculants that assist in soil phosphorus absorption and their effects on soil microbiota and the early development of maize plants. The experiment was conducted in a greenhouse at the Experimental Farm of the State University of Goiás, Ipameri, Goiás, Brazil. A completely randomized design with four replications and seven treatments was used, totaling 28 experimental units (pots). The treatments consisted of applying the recommended phosphorus (P) rate (100 kg P2O5 ha-1) alone or combined with seed inoculation with an arbuscular mycorrhizal fungus (AMF) (Rhizophagus intraradices; Rootella BR®), phosphate-solubilizing bacteria (PSB) (Bacillus subtilis and B. megaterium; BiomaPhos®), or AMF + PSB; and half the recommended P rate (50 kg P2O5 ha-1) combined with seed inoculation with AMF, PSB, or AMF + PSB. Microbial biomass carbon, soil basal respiration, microbial metabolic quotient, mycorrhizal colonization, plant height, stem diameter, and shoot and root dry weights were assessed 42 days after emergence (DAE). The best microbiological results were observed in the treatments applying the recommended P rate without inoculation and half this rate combined with PSB or AMF inoculation. The recommended P rate alone and half this rate combined with PSB, AMF, or AMF + PSB had a satisfactory effect on phytotechnical parameters up to 42 DAE. However, an apparent incompatibility between AMF and PSB was observed when combined with the recommended P rate.