Abstract: Three irrigation modes in winter wheat growth season were carried out in Heilonggang basin of North China Plain to investigate their effects on the grain yield, water consumption, and water use efficiency (WUE) of winter wheat-summer maize. The three irrigation modes included irrigation before sowing (75 mm, W₁), irrigation before sowing and at jointing stage (75 mm+90 mm, W₂), and irrigation before sowing, at jointing stage, and at filling stage (75 mm+90 mm+60 mm, W₃). With the irrigation modes W₂ and W₃, the increment of the annual yield of winter wheat-summer maize was 8.7% and 12.5% higher than that with W₁, respectively. The water consumption in winter wheat growth season decreased with increasing irrigation amount, while that in summer maize growth season increased with the increasing irrigation amount in winter wheat growth season. The WUE of winter wheat with the irrigation mode W₂ was 11.1% higher than that with W₃, but the WUE of summer maize had less difference between irrigation modes W₂ and W₃. The annual WUE (WUE_T) of W₂ and W₁ was 21.28 and 21.60 kg^-1·mm·hm^-2, being 7.8% and 9.4% higher than that of W₃, respectively. Considering the annual yield, water consumption,and WUE, irrigation mode W₂ could be the advisable mode for water-saving and high-yielding.

Key words: irrigation mode, winter wheat, summer maize, yield, water consumption, water use efficiency, organic fertilizer, acetylene inhibition, N₂O reduction, isotope characteristic value, nitrification