Effects Of Irrigation With Saline Water On Seed Maize Growth And Simulation By SWAP Model

As the background of the shortage of water resources and water-saving irrigation technology implementation status in arid regions of northwest China, field experiments were conducted in2012and2013to study the effects of saline water irrigation on water-salt distribution in soil profile and crop growth under the conditions of seed maize growth in the Shiyang River basin. At the same time, the Soil-Water-Atmosphere-Plant (SWAP) model was calibrated and validated to simulate water-salt distribution based on the field experiments and observed values. The main contents and results of this dissertation are as follows:(1) The water-salt distribution in soil was influenced by irrigation amount, root water uptake and soil texture. Under the different irrigation amount, the soil water content under deficit irrigation was obviously lower than under sufficient irrigation. As saline water irrigation was used for a long period of time, the physical and chemical properties of soil can change. It was noticed that soil water content had obvious stratification, the surface soil water content and the root water uptake soil water content were lower and the deep soil water content was higher for each treatments. It was appear that the soil salt was accumulated from the surface soil layers to the deep soil layers. The deep soil salt was higher than the surface soil salt.(2) The results show that the growth of seed maize will be restricted and yield will be decreased under water-salt stress. The impact on growth and yield of seed maize are more serious with increase of water-salt stress. Water use efficiency will be improved under deficit irrigation. But water use efficiency will be reduced under excessive deficit irrigation. Water use efficiency of seed maize also will be reduced with increase of the soil salinity.(3) With measured data of field experiments and water balance method, we calculated maximum root water uptake rate and salinity stress ratio at seed maize heading period.(4) The results showed that the SWAP model reflected the change tendency of measures values effectively and the calibrated and validated SWAP model can simulate the soil water distribution, salt distribution and yield perfectly. In seedling stage of maize, the soil water flux above40cm soil layer was given priority to with upward because of the soil evaporation. In the stage of rainfall and irrigation, the soil water flux in all soil profile was mainly down. In the stage of soil evaporation, the soil water flux below60cm migrated downward with the flux reducing gradually. There were similar regular between water and salt transport with the soil salinity flux below60cm downward. It indicates that the soil salt migrated to deep soil layers.