The Integration of Phosphorus-Solubilizing Rhizobacteria, Eisenia fetida and Phosphorus Rock Improves the Availability of Assimilable Phosphorus in the Vermicompost

Due to increasing soil degradation caused by unsustainable agricultural practices and the continued demand for quality food for the human population, it is imperative to find sustainable strategies for high-quality food production. For this reason, the objective of the present study was to evaluate the interaction between the factors of consortium of phosphorus-solubilizing rhizobacteria, addition of phosphate rock and worm load in horse manure to produce an organic fertilizer fortified with phosphorus. For this, consortia of phosphate-solubilizing rhizobacteria of the genus Bacillus (Bacillus aryabhattai, Bacillus subtilis and Bacillus cereus) isolated from the rhizosphere of Distichlis spicata were inoculated. Igneous phosphate rock (0 and 2%) was added in the vermicomposting process (with 25 and 50 g of E. fetida worms per kg of horse manure). The results obtained show that there is a significant interaction between the factors of inoculation with bacterial consortia (1 × 108 CFU mL−1), phosphate rock (2%) and earthworm biomass (50 g kg−1 of manure), and that this interaction promotes the production of assimilable forms of phosphorus for plants (such as monobasic phosphate ions H2PO4−1 or dibasic phosphate ions HPO4−2) within the vermicomposting process, having as a product an organic substrate supplemented with the optimal nutritional requirements for the development and growth of crops. This work can serve as a basis to produce high-quality organic fertilizer. However, field studies are required in order to observe the impact of vermicompost on the yield and quality of the fruits, and it can be compared with other types of fertilizers and the relevance of their use in different types of climates.