土-作物-大气系统中动态根系生长及水动力学模拟

Simulation of dynamic root growth and water transfer in soil-crop-atmosphere system

针对土-作物-大气连续系统的土壤水动力学模型对根系动态生长的模拟不理想,通过引入最新的根系生长模型理论、根长密度分布函数以及联合国粮农组织推荐的计算蒸发及蒸腾总量的模型理论,与现有的模拟水土运动的有限元程序相耦合,建立模拟土-作物-大气系统的水动力学模型.基于荷兰实验农场的小麦实验数据的模拟结果表明,在不同时期、不同深度处土壤中水的体积分数与实验值比较吻合;由于降雨和蒸发的上边界影响,上部土壤中水的体积分数随时间变化较快;除接近地表的个别根长密度模拟点偏差较大外,总体来说根长及根长密度模拟结果与实验值比较吻合;蒸腾量和蒸发量的模拟结果可靠.建立的新模型合理,可以有效地模拟土-作物-大气系统中的根系生长及水动力学.

In allusion to the case that the current soil hydrodynamic models of soil-plant-atmosphere continuum system cannot give a good prediction for rooting depth and root length density distribution, a new model for water transfer throughout growth was developed, which employing a recently proposed algorithm for simulating the dynamic root growth and the approach introduced by Food and Agriculture Organization of the United Nations for estimating the soil evaporation and plant transpiration. The soil water movement was described by a flow equation which was solved by a finite element numerical scheme. The validation of the developed model was carried out against data from a field experiment on a soil cropped with wheat in Netherlands. Results showed that the simulation results agreed with the measurement data of soil water content down the profile at intervals; and the soil water content in the top soil layer changed rapidly for the influence of rainfall and evaporation in upper boundary; the simulated root depth and the root length density down the profile at intervals were satisfactory except for few data; and the modeling results of transpiration and evaporation were reliable. So the new proposed model is reasonable, and it can model the root growth and water transfer effectively in the soil-crop-atmosphere system.