摘要
水分蒸发过程是土壤水文状况的重要因子之一。土壤水分的蒸发过程、强度及其影响深度,除与气候条件有关外,它与土壤性质,尤其是土壤的湿润程度有极为密切的关系。因此,研究不同湿度条件下,土壤水分的蒸发性能及其移动规律,对因时制宜地采取有效的保墒措施,是很重要的。
The experiment of evaporation and movement of soil water were carried out in the polymethylmethacrylate cylinders of 5 cm in diameter and 120 cm high.The soil used in the experiment was a heavy loam;and CaCl_(2) was used as the tracer.Four treatments were laid out on the basis of different soil moisture contents,they were(a)the maximum hygroscopicity,(b)wilting percentage,(c)the moisture content of the capillary bond disruption,and(d)the minimum water-holding capacity.The experimental data showed that,under evaporation condition,the lower limit of water in the liquid form in soil is near the wilting percentage.When soil moisture content is lower than the wilting percentage,the movement of the soil water in liquid form is usually extremely weak.Following the increase of soil water content from the moisture content of the capillary bond disruption to the minimum water-holding capacity,the film-moving mechanism tends to turn into the capillary-moving mechanism.The moisture of the capillary bond disruption is a turning point of change of the type of soil water movement.It has been shown in the experiment that under condition of the minimum waterholding capacity,the evaporation intensity of soil water in the first five days is always greater than that from the free-water surface.From the begining of the minimum water-holding capacity,the evaporation can be divided into three stages with the decreasing of soil water content.The equation for cumulative evaporation may be expressed as Q=AT^(b),where A and b are parameters which can be obtained from a logarithmic plotting.From the begining of the moisture of the capillary bond disruption the evaporation process can also be distinguished into three stages,but the evaporation intensities of the last two stages are two constants of minute value.
作者
杨文治
赵沛伦
张启元
Yang Wen-zhi;Zhao Pei-lun;Zhang Qi-yuan(Northwestern Institute of Soil and Water Conservation,Academia Sinica)
出处
《土壤学报》
1981年第1期24-37,共14页
Acta Pedologica Sinica
