soil water evaporation

Because the evaporation is great more than rainfall, and the ground water is deep, soil water is always in the step of wane condition and the soil nutrient are also leanness and available nutrients are scantily, which makes the eco-environment of the plateau very fragile.

由于蒸发潜势远大于降雨量，而地下水埋藏又很深，致使土壤水分经常处于水分亏缺状态，加之水土流失严重，土壤贫瘠，基础肥力低，有效养分缺乏，生态环境十分恶劣。

The surface crust of red soil formatted after rain has great impacts on runoff and sediment. It can affect the infiltration, evaporation and moisture of soil. Meanwhile the cycle of soil water may be changed by the surface crust.

红壤在降雨之后形成的地表结皮，不但影响土壤产流产沙，也影响降水入渗、水分从地表蒸发以及土壤水分状况，并可能改变土壤水分循环。

According to precipitation-balance principle, we could get reasonable density combined with soil water and evaporation.

结合刺槐林地土壤水分和蒸腾耗水特征,按照降水量平衡原理求得刺槐的合理造林密度.

The crust seals the soil and prevents the evaporation of water.

这层表皮把土壤封闭,防止水份蒸发.

Under different levels of soil moisture, the soil water evaporation covered by litter with the thickness of 0.5cm~ 2cm was less than 7.95%~ 56.79% of the soil without litter covering.

0.5mm～2mm枯落物覆盖下不同含水量的土壤水分蒸发比无覆盖的土壤减少7.95%～56.79%，枯落物层减少土壤水分蒸发的效应随枯落物层厚度和土壤含水量的增大而增加。

A mathematical Model on Soil Water Evaporation under Litter Cover

枯枝落叶覆盖下的土壤蒸发的数学模型