二维土壤蒸发过程的数值分析

TWO-DIMENSIONAL NUMERICAL ANALYSIS FOR EVAPORATION PROCESS OF THE BARE SOIL

本文从研究耕作措施出发,提出了地表平坦或地表起伏不平时二维土壤蒸发过程的数值分析方法。作为应用举例,分析了沟种垄作对苗床土壤水分与温度分布的影响,并作了田间试验验证。这一研究为农业生态学提供了一种定量分析方法。

Soil moisture and temperature of the seed zone in dry land farming are mainly affected by the surface evaporation and the structure of seedbed . A two-dimensional numerical model of evaporation from the surface of flat or undulated heterogeneous soil was developed and validated by field experiment for the purpose of optimizing tillage operations.When the surface is flat, the different evaporation rate from each surface element can be ccalculated using finite element method based on one-dimensional evaporation model by considering the different physical parameters of the heterogeneous seedbed soil. When the surface is not flat, the undulation of ridge and furrow affects the radiation and wind speed . Considering the change in energy balance and aerodynamic resistance, the surface temperature and evaporation rate from the surface of ridge and furrow can also be calculated using finite element method.Based on the governing equations of heat and moisture transfer in heterogeneous soil and the evaporation model developed by the author, a simulation program for the influence of tillage operations on seedbed moisture and temperature behavior was compiled and validated by experiment field data. As an illustration, the seedbed soil moisture and temprature behavior as affected by ridge and furrow tillage was analyzed using the model.In conclusion, this study renders a better understanding to the complicated soil evaporation processes and provides a new method for research in tillage method and quantitative analysis in agroecosystems.