Synergies and trade-offs of integrating bio-formulations with mineral fertilizers in soybean under the climate crisis: implications for productivity, profitability, and nutrient-use efficiency

Soybean productivity is often constrained by inefficient nutrient management and soil degradation. The overuse of chemical fertilizers negatively impacts soil health and sustainability. Bio-formulation-based nutrient management offers a promising alternative to improve crop productivity while enhancing soil biological activity. However, research on integrating bio-formulations with reduced fertilizer inputs remains limited. This study aimed to assess the effect of bio-formulation-based management strategies on soybean production system. The hypothesis tested whether integrating bio-formulations + 75% RDF (recommended dose of fertilizers) could achieve similar or superior productivity and profitability compared to conventional 100% RDF applications. A 3-year (2021–2023) field experiment was conducted at the ICAR-IIARI, New Delhi, with seven nutrient management scenarios [NMSc1-control; NMSc2-100% fertilizer (RDF); NMSc3-75% RDF; NMSc4-75% RDF+Bio Zn; NMSc5-75% RDF+ Bio NPK; NMSc6-75% RDF + Bio Zn + Bio NPK; NMSc7-75 % RDF + Rhizobium + MDSR14 + Burkholderiaarboris (12c)]. The bio-formulation strategy NMSc6 (75% RDF + Bio Zn + Bio NPK) recorded the highest crop growth rate (16.4 g m -2 day -1 ) and seed yield (3.1 t ha -1 ), outperforming 100% RDF (NMSc2) by 4.0–8.0%. Nitrogen uptake (280.2 kg ha -1 ), phosphorus (P) uptake (21.2 kg ha -1 ), and potassium (K) uptake (142.1 kg ha -1 ) were maximized in NMSc6. The net returns increased by 12.5% compared to conventional RDF, and production efficiency improved by 6.2%. Integrating bio-formulations with reduced fertilizer inputs enhances soybean productivity, soil health, and economic returns while reducing dependency on synthetic fertilizers. NMSc6 emerged as the most effective strategy, balancing high yield with sustainable resource use. • NMSc6 (75% RDF + Bio Zn + Bio NPK) increased soybean productivity by 4.0–8.0% over 100% RDF. • NMSc6 recorded the highest CGR (16.4 g m -2 day -1 ) and RGR. • NMSc6 improved net returns by 7.9–12.5% compared to 100% RDF. • NMSc6 increased N (103.7%), P (107.8%), and K (117.2%) uptake. • NMSc6 reduced fertilizer input by 25% without yield penalty