Abstract: Field experiments were conducted to investigate the effects of nonuniformity of sprinkler fertigation and the amount of fertilizers applied through fertigation on nitrogen uptake and crop yield during two growing seasons of winter wheat from 2002 to 2004 at an experimental station in Beijing. In the experiments the seasonal averaged Christiansen irrigation uniformity coefficient (CU) varied from 72% to 84%. Except for the fertilizer applied before planting, fertilizer was applied with the sprinkler irrigation system with a seasonal averaged CU for fertigation varied from 71% to 85%. Three levels of fertilizer applied varying from 0 to 180 kgN/hm2 were used in the experiments. The experimental results demonstrated that sprinkler fertigation uniformity had insignificant effects on nitrogen uptake and crop yield for the uniformity range tested. Also, the influence of fertilizer applied through sprinkler fertigation on crop yield was minor, while total nitrogen content for stem and nitrogen uptake increased with increasing fertilizer applied. Consequently, field experimental results obtained from this study supported that the target sprinkler uniformity of CU ≥ 75% suggested by the current national standard is high enough for minimizing the negative effects of nonuniformly applied water and fertilizers on nitrogen uptake and crop yield.

Key words: Uniformity, Fertigation, Sprinkler irrigation, Winter wheat, Nitrogen uptake, Yield