Maize nitrogen uptake and use efficiency, partial factor productivity of nitrogen, and yield response to different nitrogen and water applications under three irrigation methods

The effects of irrigation and nitrogen (N) on grain yield, actual crop evapotranspiration (ETa), N uptake efficiency (NUE), partial factor productivity of N (PFP_N), and N utilization efficiency (NUtE) of maize (Zea mays L.) under centre pivot (CP), subsurface drip (SDI) and gravity (furrow) irrigation (FI) were quantified. Field experiments were conducted in two growing seasons under the full irrigation treatment (FIT), limited irrigation treatments of 80% FIT and 60% FIT and rainfed treatment (RFT). The highest NUE was observed under limited irrigation in the order of 80% FIT > FIT ≥ 60% FIT in non-traditional treatment-1 (NT-1) in both the CP and SDI methods. NUtE increased with irrigation amount. There were strong correlations between NUtE and grain yield regardless of irrigation method. ETa increased with N amount, and the slopes of these relationships varied substantially between irrigation and N levels and irrigation methods. PFP_N increased with irrigation amount across the irrigation methods and N treatments. A higher PFP_N was observed in the lowest total applied N plots and in-season split N application treatments. The pooled data for the CP and SDI methods showed significantly higher PFP_N (20.3%) than the FI method, whereas the PFP_N values in the CP and SDI methods were equal.