Research On The Method Of Irrigation Forecast Under The Condition Of Insufficient Irrigation

Water-saving irrigation is of great significance to the sustainable utilization ofagricultural water resources in our country. Insufficient irrigation could improve waterutilization efficiency and make the overall yield and efficiency to achieve the optimal underthe condition of the limited water resources. Irrigation forecast is advantageous to thereasonable allocation of water resources in irrigation area.This study is research on the experiment about winter wheat irrigation forecasting underthe condition of insufficient irrigation in the city of Linfen in Shanxi province. Irrigationforecast model is established by using the research area of the test data.(1) The establishment and test Soil moisture dynamic simulation model. According tothe measured data of soil moisture on the whole growing period of winter wheat in2years,soil moisture dynamic simulation model based on the principle of water balance is set up. Thetest of the modeling parameters is carried out by utilizing measured data of soil moisture inthe third year. The results show that the soil moisture dynamic simulation model is feasible.We should conservate water and make useing wise of it.(2) Making irrigation schedule. Fifteen design typical years, which is the basis ofirrigation schedule optimization, is determined by long series rainfall data and frequencyanalysis method. There are two kinds of irrigation scheduling, including optimal irrigationscheduling of all hydrology typical years and optimal irrigation schedule of each hydrologytypical year.(3) Making soil moisture dynamic lower limit value. Soil water content before irrigationand crop growth and the quantity of water supply corresponding with the irrigation date underdifferent condition of irrigation water supply are determined by taking yield maximum as thetarget to optimize irrigation schedules of each design typical year. The multiple linearregression equation is set up, that is dynamic irrigation lower limit value equation, whichincludes dependent variable of soil moisture content and independent variable of the numberof days of crop growth and the quantity of water supply. This part is the innovation of this study.(4) Irrigation forecast. Taking the years of irrigation forecast as median water year,irrigation forecast is made for soil water content of whole periods of winter wheat. Dynamicirrigation lower limit value is determined by multiple linear regression equation in period ofirrigation forecast. The simulated soil water content is compared with the lower limit value.When the lowest value is higher than the simulated, irrigation is done, otherwise, noirrigation. The results show that the prediction method has certain yield increase benefit.