Movement of Soil Moisture under the Temperature Gradients

Abstract

The effect of a temperature gradient on the movement and distribution of soil moisture has been examined in closed column of soil for various initial water contents (1%-7%).
The results are as follows:
1) In all except the driest and wettest columns of soil there was a transfer of moisture towards the colder end from the waremr, that is, water evaporating from the hotter soil moves as vapor into colder soil, where it condenses and return as liquid when a favorable gradient of moisture has been established.
2) For the transfer of soil moisture, liquid flow works as a control factor and reduces the amount of net transfer due to temprature gradient.
3) The amount of a transfer of soil moisture varies with the initial water content, and for the sand (it's particle 0.175-0.5mm) the maximum transfer of moisture from the hot to the cold end occurred between 3.5% and 4.0% of the initial water content which is approximately one third of the moisture equivalent.
4) The observed net transfer of moisture coincides with the vapor flows calculated by the diffsion equation of Penman, Krischer & Rohnalter, and others quite well at the maximum transfer of moisture, but, no good in other ranges of initial water content.