Optimization Of Farming System In Irrigated Oasis Based On Theory Of Virtual Water

Virtual water is a new way for solving the problem of national or regional water scarcity. According to the theory of virtual water, the farming system of Liangzhou District of Wuwei City was taken as research object. In order to improve the economic efficiency, ecological benefit and productivity of the farming system of Liangzhou, this paper selected 8 indices such as amount of labor, net income, virtual water contents of agricultural products, unit water value, ect. and used the multi-objective decision method to assess 8 plant industry structures of Liangzhou District. The 8 plant industry structures are food crops which has large planting area (wheat, corn, potato) and economic crops which has regional characteristics (barley, corn for seed, oilseed, vegetable, grape). Through the present research, the following main results were obtained:1,According to the calculation formula of virtual water contents , the paper makes use of relevant statistical data and research findings to calculate the virtual water contents of the major agricultural products in Liangzhou District. By calculating, the virtual water contents of primary agricultural products such as wheat, barley, corn, corn for seed, oilseed, potato, vegetable, grape are 0.804m~3/kg, 0.783m~3/kg, 0.498m~3/kg, 0.473m~3/kg, 2.102m~3/kg, 0.170m~3/kg, 0.135m~3/kg, 0.210m~3/kg; Virtual water contents of countpart processed products are 1.108m~3/kg, 1.073m~3/kg, 0.664m~3/kg, 0.473m~3/kg, 5.532m~3/kg, 1.973m~3/kg, 0.135m~3/kg, 2.167m~3/kg. The highest virtual water content of primary agricultural products is 16 times than the lowest. Because vegetable and corn for seed are into the trade circulation as the form primary products, the virtual water content of vegetable and corn for seed compare with the virtual water content of its primary product has no changes, Other virtual water contents of processed products change as different process occurs correspondingly. Generally speaking, the virtual water contents of processed products are slightly higher than the virtual water contents of primary products.2,The status of virtual water on Agricultural Industry Chain in Liangzhou District show a net outflowBy analyzing the status of virtual water on 4 Agricultural Industry Chain in Liangzhou District, the status of virtual water on flour processing industry chain performance as flowed into and flowed out, but the flowed into more than the flowed out. Because corn for seed, vegetable and grape industry almost has no raw materials introduce, the content of virtual water flowed into can be neglected, the status of virtual water on Industry Chain is a completely net outflow. In view of the content of virtual water flowed out on Industry Chain, the content of virtual water flowed out on flour processing industry chain is far greater than the corn for seed, vegetable and grape industry.3,In order to improve the economic efficiency, ecological benefit and productivity of the farming system of Liangzhou, this paper used the multi-objective decision method to make the priority of the plant industry structure. This paper used the multi-objective decision method to make the priority of the plant industry structure. The results showed as following: The priority of the plant industry structure showed that: grape > corn for seed > vegetable > corn > barley > wheat > potato > oilseed. At present on the premise of resources and industry chain in Liangzhou District, the highest priority of the plant industry structure in multi-objective decision is grape, following by corn for seed, vegetables, corn, barley, wheat, potatoe, oilseed at a disadvantage in the comprehensive evaluation. Therefore, for optimization of farming system, from crop planting structure adjustment level, Liangzhou District should expand the area of grape, corn for seed, vegetable which has integrated-effective, at the same time, compress the area of the wheat, potato, oilseed which are at a disadvantage in the comprehensive evaluation; from the agricultural product processing industry level, Liangzhou District should give priority to the development of the wine, corn for seed, vegetable industry, corn starch and other industries4,Effective computing of virtual water strategy under different scenarios in Liangzhou DistrictTaking the grain output as the base in Liangzhou in 2007, assumed to reduce Liangzhou 1/3, 1/2, all of the grain output and only produce 400kg grain which the per capita of the grain is the safe-guard line respectively, and use the saving water resources to produce industrial production. By calculating, the saving water of four scenarios are 1.36×108m~3, 2.03×108m~3, 4.07×108m~3, 1.50×108m~3; The expected economic benefits of four scenarios are 72.39%, 107.94%, 217.13%, 79.96%. The results show that the saving water and the expected economic benefits in different scenarios are considerable, and the virtual water strategy has broad application prospects in Liangzhou District.