The Experimental Study And Model Validation Of The Single Water Storage On Water And Nitrogen Transport Parameters Under The Different System Temperature

In the process of Chinese agricultural development, the present situation of water shortage and the low utilization ratio of nitrogen. Water storage pit irrigation is a water-saving irrigation method which can realize the retention of water and fertilizer, it is suitable for North China mountain forest area. Combined with the National Natural Science Fund Project "Analysis of irrigation water and nitrogen coupling effect and mechanism of the soil under the condition of water storage pit"(51249002). The single water storage pit soil water movement parameters and nitrogen transport parameters in different temperature system conditions were tested in laboratory, effect of temperature on soil water movement parameters and nitrogen transport parameters is analyzed, the mathematical model is established, and the related experimental data is used to verify the mathematical model. Results are as follows:1Effects of system temperature on soil water movement parameters. The main performance is the influence of system temperature in soil water status, the physical properties, and soil structure. Elevated temperature, will make the soil water surface tension and viscosity coefficient decreases, and then increase the water capacity and change the soil water potential. Mainly displays in:When the soil bulk density, moisture content is a certain value, increased temperature will make the soil saturated hydraulic conductivity, unsaturated hydraulic conductivity, diffusion rate increased to different extent. But in contrast analysis of sensitivity to temperature and volume of saturated water rate, soil saturated hydraulic conductivity is more sensitive to the change of the soil quality and volume.2Effects of system temperature on nitrogen transport parameters. The main performance is the influence of system temperature in soil water movement and nitrifying bacteria activity in soil. Mainly displays in:In the temperature range of5℃～35℃, soil nitrogen transformation parameters (including:ammonium nitrogen adsorption parameters, ammonium nitrification and nitrate denitrification parameters) have an corresponding increase with increasing temperature.3To establish the mathematical model of single water storage pit soil water and nitrogen transport in different system temperature conditions, The model based on the assumptions:test soil is homogeneous, isotropic and undeformed skeleton. The calculation is programmed with VB language, and verified the mathematical model using indoor data. The results show that:There is reasonable concordance between the simulation values and the measured values of wetting front transport soil values, soil volumetric water content, the content of ammonium nitrogen in soil and nitrate nitrogen content in soil with the change of soil depth in different system temperature, relative error is smaller, this means the mathematical model is correct.