Effects of different straw mulch rates on soil water conservation and water-saving benefits in spring maize field

A field experiment (2007–2009) 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 conservation and water-saving benefits of spring maize field. Maize straw at rates of 0 (CK), 4 500 (S1), 9 000 (S2) and 13 500 kg/hm2 (S3) was placed on field plots. The results showed that 2-year average soil water storage in 0-200 cm soil layers during of S1, S2 and S3 were 13.9, 22.6 and 33.5 mm, respectively, higher than that of CK at the end of winter fallow, and which were 20.2, 32.6 and 42.1 mm during Sowing and Jointing periods，and which were 15.6, 19.1and 21.0 mm. All treatments with straw mulch delayed the development of maize，however，accelerated the speed of growth from the late-mid period. Grain yield of S1, S2, S3 were 7.65%, 16.19% and 17.84% respectively, significantly (P<0.05) higher than that of CK in 2008 , and which were similar to in 2009, while the latter overall less than the former. Comparing with CK, 2-year average net return of S1, S2, S3 increased by 6.53%, 16.89% and 15.95% respectively, and water-saving rates of unit grain produce increased by 5.14%, 8.35% and 7.44% respectively, and water-saving benefits increased by 50.07, 81.31 and 72.30 yuan/hm2 , respectively. Results of this study indicated that synthetically performance of S2, with 9 000 kg/hm2 of straw mulch, was better than other treatments, which is preferable for Weibei highland area in China and similar ecological region, as the precipitation was below than 390 mm during the spring maize growing season.