Optimizing Soil Nutrient Bioavailability in Cotton through Potassium Solubilizing Microbial Interventions

Cotton crop was evaluated during the kharif season of 2022 to assess the response to various potassium solubilizers in combination with the recommended dose of fertilizers (RDF) on changes in macro and micro soil nutrients. The field experiment was conducted on Vertisol at the Research Farm, ICAR-All India Network Project on Soil Biodiversity and Biofertilizer, Department of Soil Science and Agricultural Chemistry, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani. The study involved ten treatments replicated thrice in a randomized block design, comprising eight potassium solubilizing bacteria KSB-W1 (Bacillus spp.), KSB-PD-3-A (Bacillus spp.), KSB-NP-3 (Bacillus spp.), KSB-PD-3-A (Bacillus spp.), KSB-M-1 (Pseudomonas spp.), KSB-M-2 (Pseudomonas spp.), KSB-M-3 (Sinorhizobium metallidans), Fraturia auruntia, and Pseudomonas striata applied along with RDF. Cotton seeds were treated with Azatophos, and RDF was applied at sowing, while microbial cultures were applied 15 days after sowing (DAS). Overall, the results indicated that the treatment combinations of RDF + Fraturia auruntia and RDF + Psudomonos striata significantly improved the availability of macro-nutrients (N, P₂O₅, K₂O) and micro-nutrients (DTPA-extractable Zn, Fe, Mn, and Cu) in the soil, showing their potential in enhancing soil fertility and nutrient uptake in cotton cultivation.