— 17 — 



in glass tubes about 10 sq. cm., water showed a rise of 82 cm. in three 

 m.onths. But a rise of only 30 cm. was observed in sections of 900 sq. 

 cm. (30x30) enclosed, in wooden boxes. Evidently, its circulation up- 

 wards by capillary action proceeded very slowly. 



But it must be borne in mind that such a slow upward movement 

 of water is observed only when the bottom of the pile of soil is sunk in 

 the water, a condition scarcely ever observed in fields, where the ground- 

 water lies comparatively deep. On the steppe for instance it lies at a 

 depth of several tens of fathoms. 



Direct observations of soil humidity, carried out on the Odessa Expe- 

 rimental Field showed, that in the course of l'-.' to 2 months drought, 

 a field with a compact surface void of vegetation, loses water in a layer 

 not deeper than 30 cm. But in the deeper lying layers, commencing at 

 40 to 50 cm. no decrease of moisture was observed. And this period 

 gave ample epportunity of seizing the phenomena accompaning drought, 

 for a ramless couple of months is an actual drought in every sense. If a 

 process of raising soil-water by capillary action from significantly deep 

 layers, really went on in fields, it could, be determined or registered. 

 And this could be done all the more easily if the humid layer diminished 

 in thickness, for then it would be possible to affirm with confidence that 

 the whole of the humid layer had been transferred upwards; and an im- 

 poverishment of water would be observed precisely in the lower belts of 

 the humid layer. If such a process of raising or moving soil-water up- 

 wards existed in nature generally, it would not only be possible to verify 

 it during a period of drought, but as a result of the action of roots; and 

 in that case the absorption of water by the roots in the upper and mid- 

 dle parts of the humid layer should be reflected in the lower parts in 

 the shape of a diminished ratio of water. But during the course of fifteen 

 years observation on the Odessa Experimental Field no such facts have 

 been brought to light; for when the ratio of water diminished in the lo- 

 wer parts of the humid layer, an impoverishment of the water in the 

 middle and upper parts was simultaneously observed. Therefore the 

 existence of a well ordered, simultaneous circulation cf water at all thic- 

 knesses of the humid layer cannot be confirmed. It is only those layers 

 into which roots penetrate that lose water, and the thickness of the 

 impoverished and partially dried layer corresponds to the length of the 

 roots in the soil; thus, if winter wheat be sown in a field under black 

 fallow having stored up v/ater in a layer of over two metres, there will 

 be found by harvest time, an impoverished layer of from 120 to 130 cm.; 

 for this depth is the limit required by the roots of winter wheat for their 

 development (table I). 



