Organic plant nutrients in combination with inorganic sources of nutrients influence the productivity, quality, soil microbes, and nutrient use efficiency of bitter gourd (Momordica charantia L.)

Sustainable bitter gourd production requires optimising the combined organic and inorganic nutrient management. Hence, a field experiment was conducted to evaluate the impact of combined organic and inorganic nutrient amendments on bitter gourd productivity, quality, nutrient use efficiency, soil microbial activity, soil health, and profitability. Treatments were T₁: control, T₂: recommended dose of inorganic N-P-K-S-Zn-B at 120-40-85-20-3-2 kg · ha⁻¹, T₃: 5 t · ha⁻¹ vermicompost (VC) + 50% of NPKSZnB, T₄: 2.5 t · ha⁻¹ poultry manure (PM) + 50% of NPKSZnB, T₅: 5 t · ha⁻¹ VC + 75% of NPKSZnB, T₆: 2.5 t · ha⁻¹ PM + 75% of NPKSZnB, T₇: 5 t · ha⁻¹ cow dung (CD) + 75% of NPKSZnB, T₈: 5 t · ha⁻¹ VC + 5 t · ha⁻¹ CD + 50% of NPKSZnB, and T₉: 5 t · ha⁻¹ VC + 5 t · ha⁻¹ CD + 25% of NPKSZnB. Integrating 5 t · ha⁻¹ VC + 5 t · ha⁻¹ CD with 50% of NPKSZnB fertiliser (T₈) significantly boosted the bitter gourd fresh fruit yield (13.1 t · ha⁻¹), a 192% higher over control, with larger fruits, higher fruit count, and greater vine length. Treatment T₈ also excelled in vitamin C (77.6 mg · 100 g⁻¹), β-carotene (122 mcg · 100 g⁻¹), protein (18.1%), moisture content (93.4%), and total soluble solids (4.0°Brix), alongside enhanced nutrient uptake, soil health, robust microbial populations, and economic returns (4552 US$ · ha⁻¹). Treatment T₄ exhibited the highest agronomic and removal efficiencies for key nutrients. Therefore, combined application of 5 t · ha⁻¹ VC + 5 t · ha⁻¹ CD with 50% of NPKSZnB fertiliser offer a promising approach for sustainable bitter gourd production. This method not only boosts yield and quality but also improves soil health and minimises environmental risks through reducing chemical fertiliser use.