Improving Wheat Grain Yield and Nitrogen Use Efficiency by Optimizing the Fertigation Frequency Using Center Pivot Irrigation System

High efficient nitrogen (N) application method and proper N management strategies can further reduce the losses enhance use efficiency. Field experiments were conducted in 2015–2016 2016–2017 growing seasons to evaluate effects of four fertigation frequencies treatments (FT-1: all topdressing was applied at jointing stage; FT-2: 67% 33% filling stages; FT-3: 33%, 50% 17% regreening, FT-4: jointing, anthesis stages) on wheat yield, water efficiency (WUE), partial productivity fertilizer (PFPN) harvest index (NHI). In addition, one-time by surface broadcasting stage set up as a control (BC-1). The results showed that FT-3 FT-4 supplied sufficient NO3−-N 0–40 cm soil layer, which reduced risk leaching deeper layers. had highest grain WUE, PFPN NHI, with average values 9153.4 kg ha−1, 2.1 m−3, 0.74 kg−1 31.3 kg−1, respectively, followed these corresponding two years. These findings suggest split 3–4 times, is say applying approximately 16.7% stages, respectively center pivot significantly improve NHI.