Nutrient availability in phosphate and potassic rocks induced by Acidithiobacillus oxidizing bacteria to produce biofertilizers

Abstract

Production of conventional fertilizers requires significant energy consumption which increases the price of the product. In recent years, a growing interest on the application of natural products has been shown by public. The aim of this work is to evaluate the effectiveness of the sulfur bacteria Acidithiobacillus thiooxidans to promote mineralogy changes and increase nutrient availability, using phosphate and potassic rocks to produce PK biofertilizers. The study was set up in Petri dishes using 30 g of phosphate rock + 30 g of potassium rock, each rock mixed with elemental sulfur applied at two levels 10% and 20% (3 g and 6 g) in dish. The experiment was conducted in a completely randomized design with eight replications (each rock). The bacterium was inoculated applying 1 ml per g of elemental sulfur. The rocks were incubated during 180 days and mineralogical analysis by XRD and chemical analysis were processed at 30, 60, 120, 150 and 180 days after inoculation. The Acidithiobacillus produced sulfuric acid, which promoted mineralogical changes especially at 180 days after inoculation, compared with the initial time. The inoculation of Acidithiobacillus reduced pH and promoted mineralogical changes in P and K rocks with a significant increase in P and K availability, becoming a viable alternative to plant nutrition instead of soluble PK fertilizers. In addition, it showed great potential for a sustainable agriculture system.