Effect of microbial consortium on sulphur use efficiency and microbial dynamics in groundnut under semi-arid conditions of Telangana

Groundnut is a major oilseed crop, but its productivity in many regions is constrained by sulphur-deficient soils and imbalanced nutrient management. Biological solutions like microbial consortia can improve nutrient availability and sulphur oxidation, yet limited information exists on their impact on microbial population dynamics at critical crop stages. A pot culture experiment was conducted during rabi season of 2024-25 at Institute of Soil Health Management (ISHM), ARI, PJTAU, Hyderabad to study the effect of microbial consortium and sulphur management practices on microbial population dynamics at critical growth stages of groundnut (Arachis hypogaea L.). The experiment was laid out in a Factorial Completely Randomized Design (FCRD) with nine treatments and three replications. Groundnut variety K6 was grown in pots (5-7 kg soil) under varying sulphur sources (gypsum, elemental S, FYM) along with recommended NPK and microbial consortium seed treatment. Rhizosphere soil samples were collected at flowering, peg initiation and pod formation stages and populations of Rhizobium, PSB, ZnSB and SOB were enumerated using selective media and expressed as CFU × 105 g-1 soil. Results revealed a significant increase in microbial population with microbial consortium across all stages compared to treatments without consortium. Among stages, pod formation recorded the highest population of Rhizobium (up to 107.1 × 105), PSB (up to 118.3 × 105) and SOB (up to 109.4 × 105), whereas ZnSB peaked at peg initiation (up to 63.6 × 105). The maximum population for all microbes was observed in T9 (RDF + 500 kg gypsum ha-1 + FYM @ 10 t ha-1 + 60 kg elemental S) with microbial consortium.