Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

Leaching experiments of bone-meal phosphorus (P) solubilization by the sulfur-oxidizing bacteria Acidithiobacillus thiooxidans was carried out using the shake-flask methodology. The effects of bone meal dosage, bio-sulfur (bio-S) concentration, and amount of bacterial inoculum on the efficiency of P solubilization were determined. The bone meal was dissolved in bacterially produced sulfuric acid to form “soluble P.” An increase in concentration of bio-S as an energy substrate for the acidophilic A. thiooxidans increased the P solubilization efficiency. Upon addition of 5% bio-S, 10% bone meal, and 10% A. thiooxidans to the leach suspension, its pH dropped from 5.22 to 1.92 between days 30 and 40 of the leaching experiment; this resulted in an increase in water-soluble P concentration by 23.8 g P₂O₅ L^-1. The soluble P concentration in the suspension from the bioleaching experiment was >20 times higher than that in conventional liquid bone-meal fertilizers. Inorganic nutrients, such as N, Ca, and Mg, were also solubilized in the suspension during the bioleaching experiment. The role of bio-S as an energy substrate for acidophilic bacteria to leach P from bone meal during formulation of biofertilizers could potentially be exploited in the management of crop nutrients in organic farming.

Changes of phosphorus concentration in leach solutions obtained during bioleaching of bone meal by adding (a) A. thiooxidans (○, 0%; ●, 5%; ■, 10%; ▲, 20%) and (b) bio-sulfur suspension (○, 0%; ●, 0.5%; ■, 1.0%; ▲, 2.0%; □, 5.0%).