Resource‐efficient potato fertilization in acid Inceptisols using a soil‐test crop response framework: Mineral‐input savings, field validation, and screening upstream urea‐manufacturing implications

Efficient fertilizer management in acid soils requires decision frameworks that translate soil‐test variability into crop‐specific nutrient demand while minimizing unnecessary mineral inputs. This study developed and field‐validated Soil Test Crop Response (STCR) fertilizer prescriptions for potato under acid Inceptisol conditions in Meghalaya, India. A three‐phase field program conducted during 2022–2024 established fertility gradients, derived crop nutrient‐response parameters, and independently validated STCR‐NPK and integrated plant nutrient supply (STCR‐IPNS) prescriptions at target yields of 100, 125, and 150 q ha −1 . Nutrient requirements for producing one quintal of tubers were 0.56 kg N, 0.26 kg P, and 0.93 kg K. Across the prescription matrix, FYM integration reduced mineral‐N demand by 23.76–23.80 kg N ha −1 and K 2 O demand by 7.0–7.1 kg ha −1 , while realized P 2 O 5 savings ranged from 0 to 32.7 kg ha −1 depending on soil‐test P and target yield. Aggregate realized mineral nutrient‐equivalent savings ranged from 30.76 to 63.60 kg ha −1 . All six targeted‐yield treatments remained within ±10% of prescribed yields, with a mean absolute target deviation of 6.04%, and STCR‐IPNS maintained tuber yield relative to STCR‐NPK. Mineral‐N displacement corresponded to 51.65–51.74 kg urea‐equivalent ha −1 and a screening estimate of 79.7–97.4 kg CO 2 ‐eq ha −1 of gross upstream urea‐manufacturing burden potentially avoided. This indicator excludes other fertilizer‐system and field emissions. Overall, STCR‐IPNS maintained predefined potato yield targets while reducing external mineral‐fertilizer demand and supporting resource‐efficient nutrient management in acidic soils. The framework supports precise fertilizer targeting, mineral‐resource conservation, and integration of organic nutrient credits in acid‐soil potato production systems.