Split plot design experiments were conducted to study the effects of irrigation amount and timing on onion water consumption and yield on lands graded with laser guidance.The results showed that the yield decreased with increasing water

the yield of the optimal irrigation amount(420 mm) varied between 12.6 and 13.1 ten thousand kg/hm2

4.1%-4.8% higher than the treatments with irrigation amount of 840 mm.This indicated a water-saving rate of 50%.The onion yield with 7 times irrigations was higher than that with 14 times.With the irrigation quota decreased

the onion water consumption was also reduced

while the corresponding yield increased and the efficiency of water was improved.The onion water requirements showed a parabola trend

i.e.

low in the early and final growth stages and high in the middle growth stage

which was consistent with soil moisture variations.