Optimizing Irrigation Requirement of Soil Test-Based Fertilizer Recommendation Models for Targeted Yields of Cabbage and Broccoli in a Typic Fluvaquept Soil

Yield target-based fertilizer recommendation, on the basis of soil test values, remained the most logical platform which avoids possibilities of over application of fertilizers and related environmental pollution. This model is successful with assured irrigation and good crop management. The arsenic pollution of the groundwater and risk of accumulation of the pollutant in crops through irrigation water drives us to relook to further optimization of irrigation requirement without compromising yields significantly. In this purview, an attempt has been made in the present study, to manipulate moisture flexibility in yield target-based fertilizer recommendation models. Field experiments were conducted in a Typic Fluvaquept soil (23°N, 89°E) of West Bengal, India, with broccoli and cabbage in two consecutive winters of 2015–16 and 2016–17. With due cognizance of STCR recommended NPK doses, elevated and reduced fertilizer levels were administered across varied available soil moisture deficits (ASMD). To assume a possible crisp crop–nutrient–moisture relationship, we adopted the fuzzy linear regression model. Yields of broccoli and cabbage under applied nutrient and moisture interventions ranged from 3.90 (no fertilizer, 60% ASMD)—21.8 (NPK-285:40:115; 40% ASMD) tha−1 and 14.0 (no fertilizer, 30% ASMD)—84.0 (NPK-350:175:300; 30% ASMD) tha−1 respectively. The water productivity (WP) also varied widely (from 13.4 to 35.75 kgm−3 in broccoli and 4.57–109.97 kgm−3 in cabbage). Interestingly, a moderate moisture stress was observed to manage a good balance among WP and yield. Such water flexible fertilizer models designed toward a compromisable yield target may help in rendering environmental safeguard by reducing use of contaminated groundwater.