A field experiment (2008-2009) was conducted at the Heyang Dryland Farming Experimental Station in Shaanxi Province of China to determine the effects of straw mulch rates on soil moisture and spring maize ( Zea mays L.) yield. Maize straw at rates of 0 (CK), 4 500, 9 000 and 13 500 kg/hm 2 was placed on field plots. The results indicated that the average soil water storage in the 0-200 cm soil layers under the three different rates of straw mulch were 16.52, 25.52 and 34.04 mm, respectively, significantly ( P<0.05) higher than that of CK, and the average field evapotranspiration (ET) in the 0-200 cm soil layers were 4.43, 8.23 and 6.96 mm, respectively, significantly ( P<0.05) lower than that of CK during 0-60 days after sowing. Besides, the average grain yield and water use efficiency (WUE) of the treatment with 9 000 kg/hm 2 of straw mulch were optimal among the treatments, its grain yield and WUE increased by 11.03% ( P<0.05) and 9.25% ( P<0.05) compared with the CK, while it was medium with the treatment of 13 000 kg/hm 2, and lowest with the treatment with 4 500 kg/hm 2. It is suggested that the treatment with 9 000 kg/hm 2 of straw mulch is preferable for Weibei highland area in China, as the precipitation is below than 390 mm during the maize growing season.
