Conclusion
In the dryland farming area of northwest China, we found that the effects of straw mulching differed
with the variation in precipitation among the three experimental seasons. In a rainy year, there were no
significant (P>0.05) effects of straw mulch on the soil water storage, wheat yield, and WUE. However,
in a normal year, straw mulching significantly (P< 0.05) improved the soil water conditions, increased
the wheat yield, and increased the WUE. In addition, compared with the growth-period mulch treatments,
the whole-period mulch treatments obtained greater improvements, particularly the SM1 and
SM2 treatments. Because of constraints on the amount of wheat straw available, we conclude that SM2
(6000 kg ha−1
straw mulching during the whole period) is the most effective treatment for improving
wheat production in the dryland farming area of northwest China.