Irrigated Farmland Water And Nitrogen Transport Model And Numerical Simulation Study

In this paper, the study area is located within an experimental station in ShaanxiProvince Jinghuiqu jurisdiction, the soil area in the study area is189m2, winter wheat andsummer maize rotation system, this paper were studied by irrigation water and nitrogen insoil for irrigation response process, while using HYDRUS-1D model to simulate the impactof the cumulative amount of bottom soil leaching different irrigation and fertilization patternson maize growth period ammonium, nitrate, and reasonable management model to reducewater and fertilizer ammonium bottom of the soil, the cumulative amount of nitrate leaching,thereby reducing the risk of groundwater contamination, detailed conclusions are as follows:Growing corn and wheat were conducted two rounds of irrigation experiment, the mainform of water movement during the two rounds of testing as follows: Soon, deep soilmoisture content increasing trend emerged immediately after irrigation and shallow (0to70cm) and deep soil (400to500cm) moisture content changes occur to a certain extent, butthe middle of soil moisture content remained constant.in the corn and wheat growing season irrigation were carried out two rounds of tests andfound that with the continuous infiltration, soil nitrate content of irrigation water hasaccumulated a significant downward trend in migration, when two rounds of the experiment,nitrate the maximum depth migration were300cm and400cm, nitrate nitrogen in the secondround of tests in greater depth because of low intensity, long duration of irrigation watermovement in a way that caused more intense.HYDRUS-1D model will calculate the moisture content of the data, and ammoniumconcentrations measured values of nitrate and field data were fit, and function using therelative root mean square error (RRMSE) the degree of fit between the two were analysis,fitting results were below0.8, indicating HYDRUS-1D model can simulate the transportprocess water in farmland soil nitrogen.studied law nitrate vertical penetrate the soil at different depths in the HYDRUS-1Dmodel simulations using results show that soil bulk density and clay content of nitratepenetration is the main reason, and the bulk density of the influence of more large, when thelarger clay content and soil bulk density, soil nitrate penetrate the longer the time spent. the influence of different irrigation water and corn growing on soil moisture andnitrogen leakage (nitrate, ammonium) leaching using HYDRUS-1D model, the resultsshowed that when the time of irrigation in23m3(12cm) within the range (irrigated area of189m2) soil at the bottom of the water leakage and nitrogen leaching volume is small,continue to increase when the irrigation water leakage and nitrogen leaching has seen adramatic rise in volume, indicating that once irrigation value for the amount of valve23m3;When the total amount of irrigation and irrigation interval is constant, the number oftimes more irrigation, soil water inside the larger the total holding, smaller leak at thebottom of soil moisture and nitrogen leaching; When the total number of irrigation andirrigation phase Meanwhile, the irrigation interval smaller bottom soil and water leakagegreater the amount of nitrogen leaching.Overall, given the time and manner of fertilizer, the soil at the bottom of inorganicnitrogen leaching with increasing water leakage increases, the concentration of inorganicnitrogen in the soil at the bottom of the water increases the amount of leakage is reduced,while inorganic nitrogen leaching the soil at the bottom of the concentration of the soil andwater leakage at the bottom of inorganic nitrogen in the product, indicating that a greateramount of water leakage at the bottom of soil inorganic nitrogen leaching effects.the effects of different fertilizer and maize growing methods on nitrogen leaching in thesoil at the bottom using HYDRUS-1D model, the results showed that the greater the amountof fertilizer nitrogen leaching the soil at the bottom, while a one-time fertilization safetyvalve value of10kg, in the soil at the bottom of this range of nitrogen leaching loss of weightand a smaller increase marginally, when the amount of fertilizer over this range, there will bea sharp increase in the amount of the loss trend in the soil at the bottom of nitrogen leaching;when fertilizing total a certain amount of time, the number of sub-fertilization, the moresmall bottom soil nitrogen leaching, when the time of fertilization if graded corresponds corngrowth stage, it will reduce the maximum amount of nitrogen leaching in the soil at thebottom.using the HYDRUS-1D model of the traditional corn growing season soil water andfertilizer management model at the bottom of the water leakage and nitrogen leaching,respectively41.8m3and93kg/hm2, water and nitrogen loss is more serious, and according to the above conclusions presented improved water and fertilizer management, namely in theseedling stage, Paris period, jointing and tasseling corn pollination period for irrigation andfertilization, irrigation amount was23m3,22m3,22m3,22m3, respectively8kg fertilizer,7kg,7kg,7kg (total irrigation and fertilization with the traditional mode of the same), theimproved fertilizer management mode makes ammonium and nitrate content of the cropuptake increased by3.48g/m2,13.83g/m2while the soil at the bottom of the water leakageand nitrogen leaching leaching were reduced by14.6m3and32.5kg/hm2, has practicalsignificance.