Selected bacterial strains enhance phosphorus availability from biochar-based rock phosphate fertilizer
2020
de Amaral Leite, Aline | de Souza Cardoso, Arnon Afonso | de Almeida Leite, Rafael | de Oliveira-Longatti, Silvia Maria | Filho, José Ferreira Lustosa | de Souza Moreira, Fatima Maria | Melo, Leônidas Carrijo Azevedo
PURPOSE: The co-pyrolysis of biomass and soluble phosphates generates biochar-based phosphate fertilizers (BBF), which may enhance phosphorus (P) input in soil and P uptake by plants. Conversely, pyrolysis of biomass impregnated with rock phosphate results in low P solubility and may not supplement plant requirement in short term. However, bacterial strains promoting rock phosphate solubilization increases P use efficiency and can be applied to BBFs. METHODS: An in vitro assay was conducted to investigate the solubilization profile of five bacterial strains (Pseudomonas sp.—UFPI-B5-8A, Burkholderia fungorum—UFLA 04-155, Acinetobacter sp.—UFLA 03-09, Paenebacillus kribbensis—UFLA 03-10, and Paenibacillus sp.—UFLA 03-116) isolated from common bean and cowpea nodules in a rock phosphate BBF. Additionally, a pot trial was carried out aiming to investigate the influence on maize growth by inoculation of three selected strains under a rock phosphate BBF fertilization. RESULTS: Inoculations with UFPI B5-8A, UFLA 04-155, and UFLA 03-09 were efficient in solubilizing P in vitro, being closely associated with pH decrease, likely due to the release of organic acids. As for the pot trial, the dose of 400 mg kg⁻¹ of P in the BBF using UFPI B5-8A significantly increased maize shoot dry matter. All strains significantly enhanced P availability in the soil. CONCLUSIONS: Bacterial inoculation in biochar-based rock phosphate aiming to improve its fertilizer value is an inexpensive and sustainable strategy to improve maize growth and enhance available P in soil and should be further explored.
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