| Shiyang River Basin is the area with the longest history of irrigation,biggest population density, and highest utilization of water resources.While, sharpest contradiction between water demand and water supply was existed in this area,whichis the most serious environmental problems in the northwest inland river basins and the water resources limited the economical development largely. So, watershortage become the bottleneck for Shiyang River Area's development. Irrigation water consumption took up 86% in Shiyang River Area's water resource, and the main plant model here was wheat-maize rotation. So, developingwater-saving irrigation is the most effective method to sovel the problem of watershortage, and by regulating the crop patternsl to save water will bacome the key piont field.The article was taken the city of Wuwei in Gansu province for reasearch area.Firstly, five plant models were chosed, which were used in Shiyang River commonly, and field irrigation experiment was adopted to study the water requirement and water requirement lawin order to give the suitable irrigation program in this area. Then, we carried out five rotation models for the five plant models at three different irrigation levels. The experiment started in March in 2008 and ended up in October in 2009.Comparative analysis method was usedin order to compare each cropping system about its yield, water consumption, WUE and economic benefit.The main purpose of this study was to select one or more cropping patterns, which had the function of water saving capability and high efficiency to substitute the traditional wheat-maize rotation patterns. Finally, we exploratoryly chosed two rotation models, and compared their yield, water consumption, and economic benefit with wheat and maize respectivelyin order to provide practical and theoretical basis for achievement the sustainable agricultural development in Shiyang River Basin.The main results were as follows:(1) Five plant models'water requirement and water requirement law showed: Spring wheat, maize, oil-sunflower, wheat intercrop maize, wheat intercrop soybean's water consumption is 480.5 mm, 569.0 mm, 291.0 mm, 636.4 mm, 571.6 mm, respectively. By comparison, wheat intercrop maize's water consumption is the maximum, and oil-sunflower's water consumption is the minimum. For the five plant models: the key irrigation period appeared in jointing and blooming stage for spring wheat, in jointing and silking stage for maize, in squaring and blooming stage for oil-sunflower, in jointing and blooming stage for wheat intercrop maize, in jointing and branching stage for wheat intercrop soybean, respectively. The suitable irrigation times for the five plant models were four, five, two, six and six times, respectively.(2) Five rotation model for the five plant model showed: the average yield (kg·hm-2) of five crop rotation indicated that: maize-wheat intercrop maize (18181) > seed oil sunflower-wheat intercrop soybean (14988) > wheat intercrop soybean-wheat (14763) > wheat intercrop maize-oil-sunflower(14652) > wheat-maize (12554, contrast); the average water consumption (mm) indicated that: maize-wheat intercrop maize (1091) > wheat intercrop maize-oil-sunflower (938) > wheat-maize (906, contrast) > wheat intercrop soybean-wheat (852) > oil-sunflower-wheat intercrop soybean (842); the average water use efficiency (WUE) (kg·hm-2·mm-1) indicated that: oil-sunflower-wheat intercrop soybean (17.9) > wheat intercrop soybean-wheat (17.2) > maize-wheat intercrop maize (16.5) > wheat intercrop maize-oil-sunflower (15.3) > wheat-maize (13.9, contrast); the average crop economic benefit(yuan·hm-2) indicated that: oil-sunflower-wheat intercrop soybean (43290) > wheat intercrop maize-oil-sunflower (29751) > maize-wheat intercrop maize (21129) > wheat intercrop soybean-wheat (18815) > wheat-maize (15790, contrast).Take the total yield, water consumption, WUE and economic benefit of different crop patterns into consideration integratedly, we conclude that oil-sunflower-wheat intercrop soybean and wheat intercrop soybean-wheat could alternate the traditional pattern to achieve sustainable agricultural development in the Shiyang River Basin.(3) Two new rotation models showed: seed oilsunflower-winter rape's irrigation is as same as maize, but if compared to wheat and maize respectively, its net income increased 33750 yuan·hm-2 and 28035 yuan·hm-2, water consumption increased 170 mm and 69 mm, and its conresponding irrigation efficiency increased 340% and 139%,.Seed watermelon-oilsunflower's irrigation is as same as wheat, if compared to wheat and maize, net income increased 27705 yuan·hm-2 and 21990 yuan·hm-2, water consumption increased 6 mm and -95 mm, and irrigation efficiency increased 284% and 109%, respectively. The main principle of these two new rotation models was to use cash crops instead of food crops, and irrigation in different season instead of over-irrigation in summer. Thus, the two plant model optimized the plant struction, slighted the contridiction between water supply and water demand, saved resource and protected ecological environment, so as to guarantee the Shiyang River Basin's sustainable development. |
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