Study On Dynamic Simulation Of Soil Water And Salt In Farmland And The Effect Of Regulation And Control On Yield Increase

The vast arid and semi-arid regions of northern China are scarce in fresh water resources,while the vast areas of North China,Northwest China,and coastal and offshore areas have large amounts of salt water reserves.In recent years,salt water resources have been used as a backup water source for agricultural water,which has great utilization value.If salt water can be used in agricultural irrigation,the problem of limited agricultural development in China will be greatly alleviated due to water shortage.To determine a reasonable salt water irrigation system is essential for the use of salt water.Based on the theory of soil hydrodynamics,this paper selects soil temperature simulation model,soil moisture simulation model,soil salt simulation model and crop growth model,and compiles numerical simulation program through MATLAB software to study soil temperature,soil water and salt transport and crop growth.Combined with the salt water irrigation test data of Yongji County,Shanxi Province,the parameters of the model were determined and tested.According to the meteorological data of the test area from 1955 to 2013,five typical years(5%,25%,50%,75%,95%)were divided.For each typical year,irrigation system optimization was carried out to simulate different irrigation.In the system,the spatial and temporal distribution of soil water and salt and the process of crop growth,with the goal of maximizing the benefits,put forward the optimal irrigation system for different typical years.The spatial and temporal distribution of soil water and salt and the process of crop growth in different irrigation systems were simulated.With the goal of maximizing the benefits,the optimal irrigation system for different typical years was proposed.The main results are as follows:(1)Using the test data of two annual winter wheat soil moisture in the test area,the parameters of the constructed soil moisture simulation model were selected by the treatment one and two treatments.Using the parameters determined by the ratio,the soil moisture change of the treatment two was simulated.The results showed that the measured values of soil moisture during the growth period of winter wheat were in good agreement with the simulated values,and the correlation coefficient R reached above 0.755.This model can reasonably simulate the change of soil water content during the growth period of winter wheat.(2)Using the 1990-1992 winter wheat salt water irrigation test data,the salt transport module of the model constructed in this paper was determined and verified.The verificationresults show that the correlation coefficient R between the measured value of the salt and the simulated value reaches 0.883 or more.The simulation of the crop growth simulation module was carried out and tested.The verification results showed that the correlation coefficient R between the simulated and measured values of the yield reached 0.871.The results show that the model has a good effect on the temporal and spatial distribution of salt and crop yield.(3)Using the model tested and determined.Under different typical hydrological years,different salt water concentrations and different irrigation times are combined,different irrigation time is set,and crop yield is simulated to determine the optimal irrigation time with the maximum output.To achieve optimization of irrigation time.The calculation results show that the maximum yield of winter wheat is 9617kg/hm2 at 5% typical year;the maximum yield of winter wheat is 8615kg/hm2 at 25% typical year;the maximum yield of winter wheat is 9835kg/hm2 at 50% typical year;the maximum yield of winter wheat is 8626 kg/hm2 at75% typical year;at 95% typical year,the maximum yield of winter wheat is 9891 kg/hm2.(4)According to the simulation results of the winter wheat salt water irrigation and the economic benefits of irrigation water,the concentration of salt water irrigation,the results show that as the number of irrigation increases,the output also increases in general.However,after more than three irrigation,the increase in yield is reduced,and the economic benefits are also reduced.Therefore,with the maximum economic benefit as the goal,the optimal irrigation system for different typical years is given for different salt water concentrations(different salt water concentrations in different regions).