| Weibei highland is a typical rainfed agricultural zone in Northern China, winter wheat is one of the major food crops in Weibei highland areas. As uneven annual and seasonal distribution of precipitation in Weibei highland, water shortage is one of the main factor to limit grain production. Conservation tillage can effectively improve the effects of soil water preservation and crop production. As the limitation of the field experiment conditions and the long test period, the long-term observation and research of yield, soil moisture and nutrient effect of rainfed winter wheat field under different conservation tillage were lacking in Weibei highland. Win EPIC model can quantitatively simulate crop yield, soil water use characteristics and evolution law of soil nutrients for a long-period. So, to analyze and assess the effects of soil water preservation and crop production under different rotation tillage patterns in different years, the Win EPIC model was used to simulate crop yield and soil moisture effects of continuous planting winter wheat field under different tillage rotation treatments for a long-period in this article.With the validation of located experiment for six straight years(2007-2013), the Win EPIC model was used to simulate the change of yield and soil water of winter wheat under the combination of different fertilization(N75, N120, N150, N180 and N255) and conservation rotation. The main conclusions are as follows: 1. The effect of winter wheat yield and soil water preservation under different continuous conservation tillage(1) During the simulation of 1980-2009, the yield and water consumption of winter wheat all decreased with the same precipitation in Weibei Highland. It showed that ST>CT>NT. The yield and water use efficiency of ST was the best, the second was CT, NT was the last. The water consumption in growth season of ST is higher than NT and CT;(2) The monthly available soil water amount changes in 0-3 m soil layers of winter wheat field decreased trendily and obviously with the seasons, the water conservation effect of NT was the best, average of which was 86.5 mm, sub-soiling was the second, the last was conventional tillage;(3) During the simulation period, the soil moisture in 0-1 m changed with the fluctuation of precipitation in wheat field, it was more stable in 1-3 m, which only changed in rainy or dry year. The difference among the tillage treatments was not significant. 2. The effect of winter wheat yield and soil water preservation under different conservation rotation(1) The simulated wheat yield and water consumption in growth season of winter wheat decreased with fluctuation during the simulation period, the effect of yield showed that NT/ST>CT/ST>NT/CT/ST>NT/NT/ST>CT. The average wheat yield of no tillage/sub-soiling was the highest which was 3.53 t×hm-2, water use efficiency of no tillage/no tillage/sub-soiling and no tillage/conventional tillage/sub-soiling were better than others was 8.68 kg×hm-2×mm-1. The water consumption in growth season of no tillage/sub-soiling was higher than other tillage treatments;(2) The monthly available soil water amount in 0-3 m soil layers of winter wheat field decreased trendily during simulation period and fluctuated obviously with the seasons, the water conservation effect of no tillage/sub-soiling was the best, average available soil water in 0-300 cm soil layers of no tillage treatment was 107.1 mm, conventional tillage/sub-soiling and no tillage/conventional tillage/sub-soiling were the second, the last was conventional tillage;(3) The soil moisture in 0-1 m soil layers changed with the fluctuation of precipitation in wheat field, it was more stable in 1-3 m, the difference among three tillage treatments was not significant, the effect of no tillage/sub-soiling was the best.In long-term continuous winter wheat cropping system, the most reasonable conservation tillage was no tillage/sub-soiling rotation in Weibei Highland. 3. Dynamic changes of no tillage/sub-soiling winter wheat yield and soil water under different fertilization(1)The simulated wheat yield, water consumption in growth season and water use efficiency of winter wheat decreased with fluctuation during the simulation period. Along with the increase of fertilization, the simulated wheat yield,water consumption in growth season and water use efficiency of winter wheat increased, it showed: N255>N180>N150>120>N75;(2)During the simulation, with fertilization increase, the water stress days increased, but the nitrogen stress days decreased in the growing season of winter wheat. Among these five fertilizations, the water stress days of N75 was lower than others, the nitrogen stress days of N255 was lower than others;(3)As the change of precipitation, the monthly available soil water amount in 0-5 m soil layers of winter wheat field decreased trendily during simulation period and fluctuated with the seasons. The available soil water amount of N75 was the highest, its water preservation effect was better than others. Average annual soil desiccated rate of these 5 fertilization treatments were 13.5、17.1、17.4、20.1 and 23.9 mm a-1; The soil moisture in 0-1.5 m soil layers changed with the fluctuation of precipitation in wheat field during cropping simulation, the winter wheat field of these 5 fertilization treatments all appeared dried soil layer in a certain extent, the dried soil layers of N75 appeared in1.5-2 m soil layers, which of N120 and N150 appeared in1.5-3 m, the dried soil layers of N180 and N255 was in 1.5-4 m soil layers. As the increase of fertilizers, the yield and water consumption improved, the dried soil layers thickened.In long-term continuous winter wheat on no tillage/sub-soiling cropping system, the most reasonable fertilization level was N150 kg×hm-2,P2O5 120 kg×hm-2,K2 O 90 kg×hm-2 in Weibei Highland. |
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