Research Of Soil Hydraulic Properties And Nitrogen Conversion Parameters Under The Couple Of Water-Temperature-Nitrogen

In agricultural production activities,the waste of soil water and fertilizer and the pollution of the environment are becoming more and more serious.These problems restricted the development of agricultural economy and brought great pressure to the environment.The key to solve the problem of water and fertilizer is to study the law of soil water and nitrogen transformation and transformation,so as to improve the effective utilization rate of water and fertilizer and realize the efficient utilization of water and soil resources.Aiming at actuality,the method of combination with indoor experiment and theoretical analysis was usedin this article,the soil water movement parameters and nitrogen conversion parameters under the couple of water-temperature-nitrogen were studied by means of laboratory test and theoretical analysis.The technical parameters were provided for actual production activities.Specific research results are as follows:(1)The soil water characteristic curve under treatment with different temperature and nitrogen application can be described by VG model.Soil water holding capacity showed a decreasing trend with the increase of temperature and the decrease of nitrogen application rate.In the VG model,the parameters ?r,?,?s,m with the temperature and the amount of nitrogen applied to meet the improved exponential function form.On the basis of this,the VG improved model of soil water characteristic curve with comprehensive temperature and nitrogen application rate was obtained,and satisfactory simulation results were obtained.(2)The saturated hydraulic conductivity of soil showed a tendency to increase gradually with the increase of temperature and the decrease of head.The relationship between the saturated hydraulic conductivity and the temperature and the head is in line with the power relationship and the linear relationship.On this basis,the coupling model of soil saturated hydraulic conductivity with comprehensive temperature and head effect is obtained.It is proved that the model has high computational accuracy.(3)The nitrification process of soil under different temperature,nitrogen application rate and water content was in accordance with the first order reaction kinetics model.There was a positive correlation between nitrification rate and temperature,water content and nitrogen application rate.Nitrification rate constant and temperature,water content and nitrogen rate are in line with the power relationship.On the basis of this,the soil nitrification parameters model with comprehensive temperature,nitrogen application rate and water content was obtained.The results show that the model has high accuracy.(4)The soil denitrification process under different temperature,nitrogen application and water content was in accordance with the first order reaction kinetics model.There was a positive correlation between denitrification rate constant and temperature,water content and nitrogen application rate.Both the denaturation rate constant and the factor can be described by a power function.On the basis of this,the soil denitrification parameter model with comprehensive temperature,nitrogen application rate and water content was obtained,and the model simulation results were satisfied.(5)The process of ammonia volatilization under different temperature,nitrogen application and water content was in accordance with the first order reaction kinetics model.There was a positive correlation between the volatilization rate constant and the temperature and nitrogen application rate,but had a negative correlation with the water content.Both the ammonia volatilization rate constant and the factor can be described by a power function.On the basis of this,the soil ammonia volatilization parameter model with comprehensive temperature,nitrogen application rate and water content was obtained.It was verified that the simulation results of this model had high precision.(6)The isothermal adsorption curves of soil ammonium under different temperature treatments can be described by Langmuir model.The maximum adsorption capacity qm and the adsorption constant K and the temperature can be expressed by the quadratic polynomial,and the Langmuir adsorption thermodynamics model considering the influence of temperature is obtained.The simulation accuracy of the model is high.(7)The adsorption kinetics of NH4 +-N adsorption in soil under different temperature and concentration conditions showed a drastic increase and then rapid equilibrium trend.The maximum adsorption capacity is linear with the temperature and the amount of nitrogen applied.The time required for the equilibrium state and the temperature show an improved exponential function,which shows an improved power function relationship with the amount of nitrogen applied.The kinetic model of ammonium adsorption in soils with temperature and concentration was obtained,and the simulation accuracy was satisfied to meet the requirement of nitrogen adsorption kinetic model.