Response of individual and combined microbial inoculants on nutrient availability, microbial population and enzymatic activity in calcareous soil under wheat (Triticum aestivum L.)

Calcareous soils often exhibit limited nutrient availability and biological activity. A field experiment was conducted during rabi 2025–2026 at VNMKV, Parbhani, Maharashtra, to evaluate the effects of microbial inoculants on nutrient availability, microbial population and enzymatic activity in calcareous soil under wheat (Triticum aestivum L.). Ten treatments were evaluated in a randomized block design with three replications. Results revealed that application of RDF combined with Pseudomonas striata, Pseudomonas fluorescens, Aspergillus niger and Azospirillum lipoferum (T9) recorded the highest available N, P, K and S (182.89, 23.20, 560.11 kg ha−1, respectively and 14.75 mg kg−1) and DTPA-extractable Zn, Fe, Mn and Cu (0.75, 5.57, 12.01 and 3.89 mg kg−1, respectively). Also the population of bacteria, fungi and actinomycetes reached to 40.09 cfu 107 g−1 soil, 6.07 cfu 104 g−1 soil and 35.20 cfu 105 g−1 soil, respectively, in the experimental study. Treatment T9 also recorded the maximum dehydrogenase activity (35.88 µg TPF g−1 soil 24 h−1), acid phosphatase activity (38.67 µg g−1 soil h−1), alkaline phosphatase activity (70.59 µg g−1 soil h−1) and soil microbial biomass carbon (334.22 µg g−1 soil). Overall, the combined application of microbial consortium with RDF improved nutrient availability and soil biological indicators, highlighting its potential for enhancing soil health in calcareous soils under wheat.