Analysis And Experimental Study On Soil Water And Fertilizer Transport Under Different Water And Fertilizer Application Modes

Fertilizer application should be carried out according to the growth characteristics and needs of crops.The existing fertilization operations mainly include surface fertilization and deep fertilization,Which kind of operation parameters should be used for water and fertilizer application is the basis of improving water and fertilizer utilization rate and precision application,according to the two water and fertilizer application methods of surface water and fertilizer integrated irrigation and deep application of liquid fertilizer,the movement of water and solute in the soil of surface micro spray fertilizer irrigation and deep application of liquid fertilizer irrigation was analyzed to provide operation parameters for the two water and fertilizer application methods.(1)This paper introduces the working principle of the integrated equipment of micro spray irrigation and fertilization,and carries out the equipment performance test.The test shows that the equipment can realize the fully automatic irrigation and fertilization operation,effectively reduce the time lag caused by the long dissolution time of granular fertilizer,and realize the integrated irrigation of micro spray with water and fertilizer.(2)According to the characteristics of moisture distribution of micro sprinkler irrigation in the middle and late stage of winter wheat,this paper discusses the soil moisture and solute transport and distribution in mid-late winter wheat root zone under different irrigation influencing factors.First,experimentally measure the irrigation intensity under different irrigation pressures for the wheat-specific micro-spray belt,divide the effective humid area into four regions,and obtain the different irrigation intensity in the four regions as the irrigation boundary conditions;Secondly,considering the water absorption of winter wheat roots,the equations of micro-sprinkler irrigation soil water and solute movement and solving conditions were established.The numerical simulation was carried out by using the HYDRUS-2D model,and the results of simulation and experimental data were compared and analyzed.It was proved that HYDRUS-2D numerical simulation can effectively reflect the distribution of soil water content.On this basis,the water and solute distributions and dynamic changes under different irrigation pressures,different irrigation lower limits of soil,and different laying spacing of micro-spray belt were simulated and analyzed.It provides a reasonable scheme for the layout and operation of micro sprinkler irrigation network,and a theoretical reference for water-saving and fertilizer saving irrigation of winter wheat.(3)The numerical simulation and study of water and solute infiltration in no tillage and deep tillage soil were carried out.Firstly,the process of subsoiling is simulated by the discrete element software edem.According to the simulation results,the disturbance boundary of subsoiling is extracted and the regional model of subsoiling solution is established;Secondly,the equations of soil water and solute movement,boundary conditions and solution conditions were established under the deep and no tillage tillage,and the HYDRUS-2D model was used for numerical simulation.Finally,the effects of soil water and solute infiltration characteristics and distribution on Winter Wheat at seedling and germination stage were analyzed and compared.(4)In this paper,the curved surface deep loosening shovel designed and improved by the laboratory structure is used to realize the deep loosening operation and the deep application of liquid fertilizer to the deep loose soil.After the deep application of bottom fertilizer,the water and fertilizer equipment is used to control only the amount of water to irrigate the bottom soil moisture.Because of the phenomenon of covering soil in the process of subsoiling,it is not easy to observe the distribution of liquid fertilizer wet surface.The measurement of the size of liquid fertilizer wet surface was completed by the laboratory test device,and the irrigation intensity of liquid fertilizer wet surface was calculated.According to the extraction of the soil boundary model of subsoiling in the last chapter,the numerical simulation of the distribution of subsoiling liquid fertilizer deep irrigation infiltration was established.The simulation results and test data are compared and analyzed,which proves that HYDRUS-2D numerical simulation can effectively reflect the distribution of soil solute.On this basis,the solute transport and distribution under different depth of fertilizer discharge hole are analyzed,and the depth of fertilizer discharge hole in soil is determined and the fertilizer utilization rate is improved by combining the sowing position and root distribution depth of wheat at seedling stage.