[Simulated responses of winter wheat yield and soil moisture to different conservation tiliage practices in Weibei Highlands, Northwest China].

Based on the verified precision results by simulation, the WinEPIC (EPIC, environmental/policy integrated climate model) was employed to quantitatively simulate effects of three conservation tillage practices adopted during the period of summer fallow, i.e. sub-soiling, no-tillage and conventional tillage, on wheat yield and soil moisture in Weibei Highlands during 1980-2009. The results showed that during the study period, the yield and annual water consumption of winter wheat under the different tillage practices tended to decrease with fluctuation in the growing period. The yield and water use efficiency of winter wheat under sub-soiling were the highest, averaging 3.33 t . hm-2 and 8.50 kg . hm-2 . mm-1 over the thirty years, respectively, and that of no tillage was the lowest. The annual water consumption of winter wheat was .slightly higher under sub-soiling than under no tillage and conventional tillage. In 0-3 m soil layer, the available soil water content tended to decline in a strongly and seasonally fluctuating manner. No tillage performed best in soil moisture conservation, with the average available soil water content being 89.5 mm, and that of conventional tillage was the lowest. The soil water moisture fluctuated with the seasonal rainfalls in 0-1 m soil layer and kept stable in 1-3 m with no great difference among the tillage practices. Under long-term continuous cropping, sub-soiling showed the best effects on the yield of winter wheat and the most comprehensive effect on soil moisture, and was the best practice of conservation tillage for wheat lands on Weibei Highlands.