Water Leakage Characteristics And Control Techniques In Dry Farmland

The irrigation water penetrates into the soil through the surface,and most of it is lost through evaporation,while only a small part of the soil water is absorbed by crops.Underground anti-seepage can significantly reduce the deep seepage of irrigation water,promote the water absorption of crop roots,improve water utilization rate and crop yield.Through one year field positioning experiment,the influence of underground seepage control on 0-200 cm soil layer soil water transport and distribution and soil water flux variation characteristics in winter wheat-summer corn field was clarified,and the influence of underground seepage control on root growth,root water absorption rate and crop yield was clarified.The applicability of the HYDRUS-1D model to soil water simulation under different impervious treatment was analyzed,which provided theoretical basis for reducing the deep seepage of irrigation water,improving crop yield and rational application of underground impervious technology.Field plot experiment will be carried out in 2021-2022.The soil moisture content of 0-200 cm soil layer profile before and after irrigation during the growth period of winter wheat and summer corn will be measured by underground film laying and compaction treatment(40 cm above the surface).The root growth and leaf area index of winter wheat and summer corn were monitored and measured in situ,and wheat and corn were harvested at maturity stage to calculate crop yield.The HYDRUS-1D model was used to simulate the dynamic changes of soil moisture in the soil layer profile of the experimental plot during the growth period of winter wheat and summer maize,and the measured soil moisture content was used to calibrate and verify the model parameters.The simulation results of the model were used to analyze the dynamic migration of soil water in 0-200 cm soil layer and the variation law of water flux at 0 cm on the surface,50 cm,100 cm,150 cm and 200 cm underground under different impervious treatment before and after irrigation.The main conclusions are as follows:(1)The operation principle of the HYDRUS-1D model is described,and the parameters of the HYDRUS-1D model are inverted and optimized.The simulation accuracy of the Hydraus-1D model was measured according to the errors between field measured values and simulated values.The results showed that the simulation accuracy of soil moisture content without impervious measures was higher than that of compacting treatment,and that of compacting treatment was higher than that of film treatment.The HYDRUS-1D model has a good simulation effect on soil water movement under the experimental conditions.(2)According to the simulation results and measured values of the Hydraus-1D model,soil water changes under different impervious treatments were analyzed,and the soil water movement rules under different impervious treatments were summarized according to the soil water content change maps and water flux maps of different soil layers: In the third day after irrigation,the soil water content at 0-40 cm was significantly increased by layering and compaction,and the soil water content was significantly increased by layering than by compaction.Underground film laying and compaction treatment can significantly reduce the loss of rainfall and irrigation water through surface infiltration and evaporation and the water leakage at 50 cm,100 cm,150 cm and 200 cm below the surface during crop growth period.(3)The ROOT parameters of wheat and maize were analyzed by ROOT·700 root growth detection system.The results showed that the underlayed film treatment and compaction treatment had significant promoting effects on the root growth parameters of wheat and maize,and the promotion effect of underlayed film treatment on root growth was more obvious than that of compaction treatment.During the growing period of crops,membrane treatment could significantly promote the increase of root water absorption rate.The impervious film and compacted layer effectively delayed the infiltration rate of soil water,made the retention time of irrigation water in the root layer of crops become longer,increased the water storage and moisture retention capacity of the root layer soil,and the impervious and leakage control effect of the impervious film was more significant than that of the compacted layer.(4)During the growth period of winter wheat and summer corn,the leaf area index of winter wheat and summer corn was significantly increased by underground film layering and compaction treatment,and the growth and development of crops were promoted.By comparing the crop yield and its component factors under different impervious treatment,it was found that compared with the crops in the plots without impervious treatment,the underground membrane layering and compaction treatment could significantly improve the crop yield,and the effect of membrane layering was more significant than that of compaction treatment.