土壤中硝态氮淋洗的传递函数模拟和预报

运用传递函数模型(Transfer Function Model,TFM)作为随机模拟工具，对灌溉入渗重分布条件下非饱和土壤中硝态氮的运移进行了数学模拟。获得了实验条件下土壤中硝态氮迁移时间的概率密度函数和中值与均值迁移时间及运移体积分数，仿真了实验期间硝态氮的出流浓度动态，估算了硝态氮的累积淋洗量。

A transfer function for the simulation and prediction of nitrate-nitrogen leached in soil

The leaching losses of indigenous and applied nitrate-nitrogen were monitored using non-weighting lysimeter in a field of loamy sandy soil under the condition of infiltration and redistribution.Ponded irrigation was treated as a pulse input to the soil volume within which an operational defined transport volume Vst exists.Within Vst nitrogenous fertilizer could experience various physical,chemical and biological reaction on its passage to the drains.The transfer function model developed by Jury etual and white was applied to simulate nitrate-nitrogen transport through the unsaturated soil under unsteady flow.The probability density functions of the travel time of the nitrate-nitrogen transport under the experimental condition were determined from the normalized rates of loss of nitrate-nitrogen mass to the drains.The parameters including the median and the mean travel time,fractional transport volume were calculated.Furthermore,the dynamics of nitrate-nitrogen concentration in the effluent and the cumulative quantity of nitrate-nitrogen leached during the experiment were estimated using the equations proposed by White.The predicted result is in good agreement with observation data.