MODEL TESTS OF VAPOUR MOVEMENT IN SOIL 77 



used by the test plants which wilted 2 days later than the controls. From the 

 desiccated soil less water could be extracted and transferred upward than 

 from a moister soil. 



The quantity of water, however, moved at these low temperatures was 

 much smaller than under the influence of higher temperatures though the 

 temperature gradient remained the same. 



T-30 



days 



Fig. 7. Ecological effect of an inverse temperature gradient on the vapour movement 

 and condensation in soils of different moisture, with rooted plants. For key, see Fig. 3. 

 Vapour tension of air: 60%. 



