Potassium Solubilizing Potential of Native Bacterial Isolates from Cotton Rhizosphere of Rainfed Vertisols

In India, there are no exploitable potassium (K) reserves and the entire demand of K fertilizers is met by imports. Though Indian soils are naturally rich in K, plant K requirement is partially fulfilled owing to their slow release rate. Application of potential K solubilizing bacteria can improve K solubilization and its availability. We conducted studies to isolate potential native K solubilizing microorganisms from cotton rhizosphere for better K availability for cotton. K solubilization by the short-listed strains showed significant differences in K release (mu g/ml) compared to uninoculated control at different intervals. The pH of culture media decreased from 6.50 to 4.63 with prolonging incubation period due to inoculation of K solubilising bacteria. There was direct correlation between pH decrease and K solubilization. The 16S rDNA gene sequencing identified these short-listed isolates as Lysinibacillus fusiformis, Enterobacter sp., Brucella intermedia, Enterobacter cloacae, Alcaligenes faecalis and Enterobacter hormaechei. Acidification was the major mechanism for K solubilization by these isolates. Development of microbial consortia with these isolates has potential for field applications to meet a substantial part of the crop's K requirement which can in turn reduce India's dependency on imported K fertilizers.