Numerical Simulation For Water And Nitrogen Transport Of Water-storage-single-pit Irrigation

Water shortages and environmental pollution has become a worldwide problem. Crop water and nitrogen are essential nutrients, but a lot of fertilizer is one of the causes of environmental pollution, and therefore the study is to promote the rational development of agriculture irrigation, fertilization, to avoid environmental pollution caused by fertilizer urgent needs. By reading a lot of literature on salt and water movement in the study was reviewed, with the National Natural Science Foundation of China (50979065), for the northern arid and semi arid areas of orchard irrigation and fertilization problem, applied irrigation water storage pit water and nitrogen transport for a laboratory test, numerical simulation by finite element method is studied, achieved the following results:1,After a single water storage pit irrigation, water to the center axis of symmetry of pits is concentrated in the deep; water rate from the center to the surrounding water storage pit gradually decreased, and the maximum appears in the bottom of the pit nearby. The distribution of water is conducive to water absorption and utilization by crops, but also significantly reduces water evaporation and deep percolation, or on the water storage pit irrigation water holding capacity of the well reflected.2,After irrigation through water storage pit, the distribution of nitrogen with water movement in the pit shaft as the center of the wetting range. Ammonium increased as the radial distance decreases, the maximum in the vicinity of Storage pit wall; nitrate with increasing radial distance increases, the maximum value at the wetting front is that the solute front and nitrate coincide wetting front. This distribution makes it easy with nitrogen absorption and utilization of water by crops, and can effectively reduce the leakage of ammonia volatilization and nitrate losses, but also for water storage pit irrigation and fertilizer of expression.3,Assuming isotropic soil, the skeleton on the basis of deformation are established water and nitrogen transport in two-dimensional mathematical model and solved using the finite element method; determination of parameters of the test based on the use of C language computer program to calculate the simulation results obtained, and results were compared with the experimental analysis, simulation in good agreement with the experimental data, which show that the construction of the mathematical model can reasonable simulation of single pit storage conditions of water and nitrogen transport in the irrigation of the actual situation, the numerical solution is feasible.This paper studies the law of water and nitrogen transport, the distribution of water and nitrogen under the Single Water Storage irrigation, and the numerical simulation results of their research on irrigation and scientific and rational fertilization, reduces nitrogen Pollution of the environment is significant.