Integrating Nano-DAP and Inductive cum Targeted-Yield Equations to Improve Maize Productivity and Nutrient Use Efficiency in Alfisols of Karnataka

Soil-specific nutrient management enhances maize productivity in Alfisols . This study developed and validated Soil Test Crop Response targeted-yield equations that integrate conventional NPK, farmyard manure and foliar-applied nano-DAP to improve nutrient use efficiency and profitability. Fieldwork included a fertility-gradient trial, derivation of nutrient-requirement and contribution parameters, and verification trials across low, medium and high fertility strips at ZARS, GKVK, Bengaluru. Fertilizer prescription equations were produced for NPK alone and NPK + FYM; nano-DAP was used as a foliar supplement. Verification compared STCR targets (9 and 10 t ha⁻¹) against general recommended doses and soil-fertility rating approaches in an RCBD. STCR NPK + FYM consistently attained higher kernel (≈ 9.7–9.9 t ha⁻¹) and stover (≈ 13.7–14.4 t ha⁻¹) yields and increased N, P and K uptake versus conventional methods. Mean nutrient requirements were 1.20–1.28 kg N, 0.48–0.52 kg P and 1.68–1.77 kg K per t target. Integration of FYM and nano-DAP lowered inorganic fertilizer needs while improving fertilizer contribution, recovery, agronomic efficiency and partial factor productivity. Response-yardstick validation fell within ± 10% tolerance and value–cost ratios showed economic viability. STCR prescriptions combined with FYM and nano-fertilizers thus boost productivity, nutrient efficiency and profitability in Alfisols of Karnataka.