Reasearch On Decision Making Support System For Precise Irrigation Of Wheat In The Hexi Oasis Irrigation Areas

China is a large agricultural country, irrigation is one of the key links and technical measures of agricultural production.precise irrigation of crops is a precise requirement to meet the growing process of irrigation time, irrigation volume, irrigation location, and the irrigation component, to maximize Improve water-using efficiency and protect agricultural production, to implement agricultural sustainable use of water resources. There are abundant light and heat resources, economic, scientific and technical bases are relatively firm in Hexi Oasis Irrigation Areass. With the natural advantage to the development of agriculture, it will provide favorable conditions for spring wheat growth. However, the obvious shortage on water supply has an impact on a stable yield and acreage to expand spring wheat planting. This paper is taking the development and the research of irrigation decision-making system (Irrigation Decision Support System) as a background, has realized the systematization, standardization and automation of meteorological factor information, crop growth information, soil moisture development information and the stocking, reading and taking of the results of decision-making. With Visual Basic6.0, it has established a wheat precise irrigation decision-making support system in the oasis irrigation areas utilizing precise irrigation technical practice. On the basis of experimental data on wheat culture in Hexi irrigation areas and of the meteorological information on different durations of time, the supporting system has carried out a simulated analysis on farmland moisture change. The moisture index has appraised the actual situation of soil water content, then determined the specific time to fill water, has offered scientific basis for controlling soil moisture, raising moisture using efficiency and realizing high yield while saving water. The main findings are as follow:1. In Prediction irrigation system, Computer has undertaken automatically monitoring, calculation and information management, established computer models and decision-making systems based on a water balance principle, which use soil moisture balance principle and determine the required parameters according to the time scale, to handle the soil moisture budget items correctly, and to get the simulated effect needed under the condition of longer time step. This computer model has some commonality as it takes environmental factors into consideration. The forecasting system used the current soil moisture to calculate the soil moisture in the next stage, can forecast wheat irrigation timing and amount of irrigation.2. The key points of this paper are forecasting Crop Evapotranspiration and determining the amount of groundwater recharge application of the method in balance method. In this paper, the using of Penman - Monteith equation in evapotranspiration is recommended by the Food and Agriculture Organization of the United Nations (FAO), with relatively small error in the method of calculating possible evapotranspiration in 1998. Utilizing professional analysis software SPSS to handle the testing data and through multivariate line shape return method, an ET0i forecast model can be established.3. Among the hydrological agricultural elements, the soil moisture has a direct impact on crop growth and development, so the simulation of the soil moisture dynamics is a key to an accurate prediction to the wet and dry of soil condition. Water use index can be used to forecast wet and dry of soil conditions, to simulate soil moisture and crop growth.4. The surface evaporation and actual wheat evapotranspiration can be used to establish a mathematical model formula to simulate actual evapotranspiration. The station usually uses surface evaporation to observe the soil moisture evaporation size under certain weather conditions, which is related to crop evapotranspiration by a certain quantitative relationship. The use of test data of surface evaporation (X) and wheat actual evapotranspiration (Y) in Water-saving Experiment Station of Gansu Academy of Agricultural Sciences in Zhangye, the corresponding mathematical modeling formulas are established, which are the regression equations of surface evaporation and wheat evapotranspiration: Y = 1. 208749+0.605794X F =9.05466^**( F_0.01=7.72) R =0.5082^**( R_0.01=0.478)Using the regression equation, the actual wheat evapotranspiration in Hexi area can be simulated. From the results, the error is relatively small between the actual observation and Penman - Monteith equation the calculated result. Considering the possible system error brought by the instruments, the system has high credibility.5. Taking the Microsoft small-sized database of Access Component 2.6 as carrier to found systematic database, and taking Visual Basic6.0 as major programming tool, the programming of decision-making system has been completed. Developing wheat precise irrigation decision-making system in Hexi oasis irrigation areas, using computer to handle farmland environmental parameter, formulating policy through decision-making support system can solve the important problems of supplying water at the right moment and of crops needing water. The blindness in irrigation has been avoided and the level of scientific management has been raised, making traditional agricultural wheat irrigation take a new step forward.