Nitrate leaching from applied fertilizer is reduced by precision nitrogen management in baby corn cropping systems

Abstract

In-situ field studies were conducted for three consecutive baby corn (Zea mays L.) growing seasons to quantify the amount of reactive N flowing beyond the rhizosphere while defining mitigation strategies. The N applications based on plant need were agronomically more efficient than the fixed-time blanket N applications. Average area-scaled leachate N losses in the winter season were 24 and 8% higher than the summer and spring seasons, respectively. A smaller root system at low N rate likely restricts plant N uptake and accelerates the magnitude of N leaching factor ranging from 6 to 9% in different seasons. Leachate N-flux peaks were more pronounced at early growth stages, attributed to the N supply in excess of the plant need. Residual soil mineral N varied little despite a wide range of fertilizer N rates, hence there was no evidence to support the idea that soils should be replenished for N removal by crops at fixed growth stages. Rather, N losses to the environment were greater using fixed-timing blanket N applications, which can be mitigated by a shift to N fertilization based on assessment of plant need. Use of the PAU-leaf colour chart and chlorophyll meter to guide need-based fertilizer N topdressings reduced average leachate NO₃¯-N load by 69% over blanket N use practice, while producing an average 17% higher cob yield in baby corn. Hence, the blanket N use practices should be replaced with need-based N management strategies to mitigate environmental footprints of N use in the baby corn based cropping system.