Integrated nutrient intensification and microbial consortia enhance productivity, profitability, and soil biological functioning in Indian mustard under variable climatic conditions

Mustard ( Brassica juncea L.) productivity in the Indo-Gangetic Plains is increasingly constrained by declining soil fertility, climatic variability, and inefficient nutrient management. This study evaluated the combined effects of intensified NPKS fertilization and microbial consortia on mustard productivity, soil biological health, and profitability under variable climatic conditions. A two-year field experiment (2021–22 and 2022–23) was conducted in a split-split-plot design comprising three fertility levels [75%, 100%, and 125% of the recommended dose of fertilizers (RDF)], two mustard hybrids (‘Pro Agro Hybrid Mustard-5222’ and ‘Pioneer Hybrid Mustard-45S46’), and three biofertilizer treatments [control, phosphate-solubilizing bacteria + sulphur-dissolving bacteria (PSB+SDB), and NPK microbial consortia].The treatments exerted significant (P < 0.05) effects on crop productivity, soil enzyme activities, and microbial populations. Application of 125% RDF significantly increased seed yield (2767 kg ha -1 ), stover yield (6075 kg ha -1 ), and biological yield (8843 kg ha -1 ) compared with 75% RDF. Higher fertility levels also enhanced soil biological properties, including dehydrogenase activity (DHA; 67.5 μg TPF g -1 soil day -1 ), alkaline phosphatase activity (ALP; 148 μg g -1 h -1 ), and soil microbial biomass carbon (SMBC; 153 μg kg -1 soil), along with greater bacterial (50 × 10 7 CFU g -1 soil), fungal (21.3 × 10 5 CFU g -1 soil), and actinomycetes populations (23.5 × 10 5 CFU g -1 soil). Among the hybrids, ‘Pioneer Hybrid Mustard-45S46’ exhibited superior performance, producing ∼6% higher yield and ∼13% greater soil biological activity than ‘Pro Agro Hybrid Mustard-5222’. Application of NPK microbial consortia further enhanced seed yield (∼12%) and DHA (∼16%) over the control treatment. Overall, the findings demonstrate that integrating intensified fertility management with high-performing mustard hybrids and microbial consortia substantially improves productivity, soil biological functioning, and profitability under variable climatic conditions. These integrated nutrient and microbial approaches offer a promising strategy for sustainable mustard intensification in mustard-growing regions of the Indo-Gangetic Plains.