Study On Simulation And Experiment Of Irrigation In Soil Water And Nitrogen Transport Under The Wide Ridge Furrow

Wide furrow irrigation technology is widely used in some areas of China.It has high water and fertilizer use efficiency in the ground irrigation mode,In order to further study the characteristics and laws of soil water infiltration and nitrogen transport in wide furrow irrigation,based on the related literatures of wide furrow irrigation theory and technology at home and abroad,this study was carried out by a combination of laboratory tests,theoretical analysis and numerical simulation.On the basis of the soil box test,the simulation effect of HYDRUS-2D under the test conditions was analyzed to explore the effects of pressure head and soil initial water content on cumulative infiltration and wetting body migration,and nitrogen transport under different fertilizer concentrations.The shifting characteristics provide a theoretical basis for further research on how to improve the utilization rate of wide furrow irrigation and fertilizer.The main findings are as follows:(1)The cumulative infiltration of soil in wide furrow irrigation shows a trend of increasing with the increase of pressure head and the decrease of soil initial water content.An empirical model of cumulative infiltration and infiltration time of wide furrow irrigation was established.The relationship between model coefficient and initial water content of pressure head and soil was fitted and analyzed.The cumulative infiltration model was tested and verified.The model calculation effect is good.(2)The vertical and horizontal wetting front migration in the process of wide furrow infiltration gradually increases with the increase of pressure head and initial water content,and the wet front migration distance and infiltration time have significant power function.The relationship between the wet front and the infiltration time,the pressure head and the initial moisture content of the soil is established.The model has a high reliability.(3)The distribution of nitrate nitrogen and ammonium nitrogen in the wetting body of the wide furrow filling system and the nitrate and ammonium nitrogen mass fractions at the same position increased with the increase of fertilizer concentration..The migration and distribution of nitrate nitrogen is similar to the law of water infiltration,showing the characteristics of nitrate nitrogen movement with water,while the adsorption of ammonium nitrogen is mainly close to the water surface due to the adsorption of soil surface.Scores have a greater impact and have less impact on their distribution.The cumulative infiltration and wetting front migration models constructed in this paper do not take into account the effects of soil texture and bulk density.Next,the effects of soil texture and bulk density on the model coefficients need to be further explored.At the same time,in the nitrogen transport experiment,the concentration gradient of fertilizer solution is less,and the simulation time is shorter.The nitrogen transport and redistribution in wide furrow irrigation,water and fertilizer coupling are still to be further studied.