冬小麦生长土壤中硝态氮动态的集中参数模型模拟

Modeling Nitrate Dynamics in Root Zone with Lumped Parameter Model under Winter Wheat Growth

应用包含有限参数的集中参数模型(LPM)来模拟根区NO3-N的浓度。为率定和检验模型,在野外进行6个小区的水氮动态试验,并根据有关文献确定相关参数,然后借助于其中的2个小区实测资料对作物根系吸氮参数进行优化μ。模拟结果表明,模拟值与田间实测值基本吻合,说明所采用的模型及所确定的参数可用于模拟和预测根层土壤中NO3-N的变化规律。最后,对LPM进行了灵敏度分析,结果表明模拟结果对硝化参数k2、根系吸氮参数μ最为灵敏,并且随着尿素水解参数k1、硝化参数k2增大而增大,随着根系吸氮参数μ、反硝化参数k3的增大而减小。

Prediction of NO^-_3-N concentration in unsaturated zone is difficult owing to the complex nature of processes dominating the fate of N in soils. Many numerical models based on soil water flow and solute transport have been developed for simulating the nitrogen behavior in the soil-plant system, however it is still difficult to yield a good result when applying them in practice, because of the difficulties of determining the parameters existed in the models. A lumped parameter model was used in this paper to simulate the concentration of nitrate in root zone. Data set collected form a field experiment with six small plots was used to calibrate and validate the model. After selecting parameters from relative literatures, the data sets from two of the six plot was used to optimize the coefficient of plant uptake rate μ with minimum relative errors between the measured and calculated nitrate concentration as its indicator. Simulation was then conducted. Results show that the calculated nitrate concentration by the model agrees well with the measurement, which implies that the model and the parameters both selected form the literature and determined by optimization are capable of being used to simulate and predict the nitrate dynamic in root zone. Sensitive analysis of model was also conducted, and the result indicates that LPM is mostly sensitive to the coefficient of nitrification rate k_2 and the coefficient of plant uptake rate μ . The calculated nitrate concentration in the root zone increases with the increase of the coefficient hydrolysis rate k_1 and the coefficient of nitrification rate k_2 , while decreases with the denitrification rate k_3 and the coefficient of plant uptake rate μ .