Lysinibacillus sphaericus as a Nutrient Enhancer during Fire-Impacted Soil Replantation

Over the past ten years, more than twenty fires have affected the El Noviciado estate located in Cerro Majuy, Colombia, leading to a loss of soil nutrients and infertility. Lysinibacillus sphaericus, a Gram-positive, mesophilic, and spore-forming bacterium, can be used in soil amendment in the replantation processes, given its ability to fix nitrogen, and nitrify, and solubilize phosphorus, increasing soil nutrients used for plant growth. In this study, we evaluated the soil-amendment potential of L. sphaericus by monitoring the nutrient content of a selected fragment of soil in the El Noviciado estate. For this purpose, we added a mixture of L. sphaericus OT4b.31, OT4b.49, CBAM5, III(3)7, and 2362 strains and determined the ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations in soil. Alnus acuminata sbsp. acuminata, a native model plant known for its restoration effect, was used for replantation. Results indicated that soils with added L. sphaericus presented significant differences in ammonium, nitrites, nitrates, phosphorus, and indole acetic acid concentrations when compared to control soils. Further, results showed no significant differences between soil that had been pre-inoculated in greenhouse and soil directly inoculated in field. We propose that L. sphaericus could be a good nutrient enhancer and plant growth promoter that can be used for the amendment of fire-impacted soils and replantation treatments.