中文摘要：

模拟覆盖条件下的土壤蒸发对于农田水管理具有重要的作用。该文分析了留茬和秸秆覆盖模式下影响土面蒸发的因素，提出了留茬覆盖模式下蒸发阻力和土面蒸发模型，基于试验数据确定了公式中的参数。主要结果和结论：当表层2 cm土壤含水率高于0.23 cm3/cm3（约60%田持）时，土面相对蒸发量（土面蒸发量与20 cm蒸发皿蒸发量比值）基本保持稳定；当表层2 cm土壤含水率在0.05～0.23 cm3/cm3之间时，土面相对蒸发量随土壤含水率的降低而线性减小。覆盖会明显降低土壤蒸发，覆盖阻力随秸秆覆盖量增加呈指数增长。当表层2 cm土壤含水率在0.05～0.23 cm3/cm3之间时，土壤表面阻力随土壤体积含水率降低而线性增加。验证结果显示建立的土面蒸发模型及相应阻力参数能较好的模拟覆盖条件下的土面蒸发量。

英文摘要：

Evapotranspiration is the main way of soil water depletion in field, and soil evaporation is an important part of evapotranspiration, and it may account for 32%-50%of the total evapotranspiration during the whole crop growth period. Soil evaporation does little effect on the formation of crop biomass and yield, so reducing soil evaporation is important for improving water use efficiency and agricultural water saving management. In recent years, straw mulching has been used widely due to its capability of improving soil structure, increasing soil organic matter, reducing soil evaporation and maintaining soil water content. Mulching affects exchange of energy and heat between soil surface and free air, so the mechanism for soil evaporation under mulching condition may be different from that without mulching. Considering the fast development of straw mulching, therefore modeling soil evaporation under straw mulching is of important for making agricultural water management. In this paper, the factors （soil water content and mulching amount） that affect soil evaporation had been analyzed, the values of mulching resistance were calculated, the equations for calculating resistance of mulching and the resistances of soil evaporation and soil evaporation under straw mulching had been established, the parameters for the equation had been determined. The experiment was carried out from late July to middle August in 2010 and from middle July to middle August in 2011, respectively. The undisturbed soil with winter wheat plants was prepared and put into plastic buckets when winter wheat was maturity, two main treatments （stubble and stubble＋mulch treatments） were set up, there were five sub-treatments for each of the two main treatments. The stubble heights for stubble treatments were 0, 5, 15, 25, 35cm. Stubble heights were 0, 5, 15, 25, 35 cm with mulching amounts of 0.47, 0.43, 0.348, 0.267, 0.187 kg/m2 in stubble＋mulch treatment, respectively. The total biomass （stubble biomass） for each stubble treatment w