利用环刀法快速原位测定土壤蒸发量

原位准确快速测量土壤蒸发量，对研究干旱与半干旱地区土壤蒸发规律和水量平衡计算具有重要意义。本研究采用环刀法分别在两种质地土壤（风沙土和黄绵土）上原位测量土壤蒸发量，并与传统微型蒸发器法测定结果进行分析对比。结果表明:在风沙土上环刀法表层（0 ~ 5 cm）土壤日平均蒸发量为微型蒸发器法蒸发量的81.68%，而在黄绵土上仅占60.71%。在风沙土上环刀法四层累加值（0 ~ 20 cm）与微型蒸发器法测定结果极显著相关（P < 0.01，R2 = 0.52），RMSE为0.84，在连续无降水事件发生时，二者测定结果接近。在黄绵土上环刀法（0 ~ 20 cm）与微型蒸发器法测定结果极显著相关（P < 0.01，R2 = 0.59），RMSE为1.07，在连续无降水事件发生时，二者测量结果差异明显，但降雨强度较小的事件发生后，二者测量结果一致。因此，环刀法可以用于准确快速原位测定土壤蒸发量，但降水事件会对环刀测量土壤蒸发量结果产生显著影响。

Rapid In-situ Determination of Soil Evaporation with Cutting Ring Method

Accurate and rapid measurement of soil evaporation in-situ is of great significance for studying soil evaporation and water balance in the arid and semi-arid regions. The evaporation in-situ on the Aeolian soil and the Loessial soil was measured by using the cutting ring method. And then the results obtained by the cutting ring method and the traditional micro-evaporator method were compared. The average daily evaporation rate at the surface layer (0 - 5 cm) by using the cutting ring method was 81.68% and 60.71% of that by using the micro-evaporator method on the Aeolian soil and Loessal soil, respectively. There was an extremely significant correlation between the accumulative soil evaporation at four layers (0 - 20 cm) by using the cutting ring method and the results by using the micro-evaporator method on the Aeolian soil (P < 0.01, R2 = 0.52), and the RMSE was 0.84. In the case of continuous non-precipitation events, the results were approximate between the two methods. There was an extremely significant correlation between the determination results by using the cutting ring method (0 - 20 cm) and by using the micro-evaporator method (P < 0.01, R2 = 0.59) on the Loessial soil, and the RMSE was 1.07. The measurement results by using the two methods were significantly different under no continuous precipitation event, while they were consistent after the occurrence of an event with a low rainfall intensity. Although the cutting-ring method can be used to accurately and rapidly measure soil evaporation in-situ, precipitation events would have a significant impact on the cutting-ring method.