SYNERGISTIC EFFECTS OF ZINC, BORON AND MOLYBDENUM COMBINED WITH BIOFERTILIZERS (Bradyrhizobium INOCULATION) ON GROWTH AND YIELD OF SUSTAINABLE SOYBEAN (Glycine max L.) CULTIVATION

A field experiment was conducted during the Rabi season of 2025–26 at a farmer’s field in Charbata, Subornochar, Noakhali, Bangladesh to evaluate the combined effects of zinc (Zn), boron (B) and molybdenum (Mo) with BINA-biofertilizer on growth, nodulation, nitrogen assimilation and yield of soybean (Glycine max L. cv. Binasoybean-4) in coastal saline conditions. The study was laid out in a randomized complete block design with three replications and consisted of five treatments: T1 (NPKS control), T2 (PKS + BINA-biofertilizer), T3 (NPKS + Zn + B + Mo), T4 (NPKS + Zn + B + Mo + BINA-biofertilizer) and T5 (N 50% + PKS + Zn + B + Mo + BINA-biofertilizer). The application of combined micronutrients and biofertilizer substantially increased vegetative growth, nodule formation and productivity. The application of (NPKS + Zn + B + Mo + BINA-biofertilizer) formed the tallest plants (53.17 cm), highest number of branches (4.20) plant⁻¹, maximum nodules (42.40) plant⁻¹, highest seed yield (2.62 t ha⁻¹) and stover yield (3.48 t ha⁻¹). The dose of (N 50% + PKS + Zn + B + Mo + BINA-biofertilizer) yielded statistically equivalent seed (2.54 t ha⁻¹) and stover (3.45 t ha⁻¹) while reducing synthetic nitrogen input by 50 %. In the case of Nodulation, plant nitrogen content, nitrogen uptake and nitrogen harvest index recorded maximum at T4 (NPKS + Zn + B + Mo + BINA-biofertilizer) treatment, followed closely by T5 (N 50% + PKS + Zn + B + Mo + BINA-biofertilizer). The adoption of Zn (4 kg ha⁻¹), B (1 kg ha⁻¹), Mo (0.5 kg ha⁻¹) and BINA-biofertilizer @ (1.5 kg ha⁻¹), either with full or partial NPKS, is recommended for sustainable soybean production in coastal belts of Bangladesh.