III. The laws of the circulation of water. 



In order to explain the phenomena of drought, it is necessary to 

 investigate the processes of water distribution in the soil previous to the 

 droughe, and to keep them under observation during the period of drought. 

 Undoubtedly this will be possible, if the laws of water circulation in the 

 soil be established, both in superficial layers and in deeper ones, but 

 accessible to the roots of plants. 



Water circulates in the soil upwards, downwards and sideways. 



As regards the circulation in an upwards direction, there exists a 

 wrong impression, which our literature has almost made a household 

 word. It is maintained that water can rise to the surface from the deep 

 layers by capillary action. I shall not name the authors who maintain 

 this theory — they are too numerous: but I do not know of a single 

 author who could prove this proposition. Of course, by „deep" soil layers 

 almost any measurements may be understood: 50 or 200 cm., 35 or 70 

 feet. But it must be admitted that deep layers, from which it is desired 

 to raise water into higher ones, are those, the water of which is inacces- 

 sible to the roots of plants unless it be raised: if it were otherwise, 

 there would be no object in drawing the water upwards, inasmuch as 

 the roots would get at this water, if it existed in accessible layers, 

 although perhaps not until they reached a somewhat late development. 

 Consequently by the word ,.deep" must be understood those layers into 

 which the roots of cultured plants do not strike. 



The root-system of cnltivated plants and its role in the distribution 

 of water especially its upwards movement bu the roots will be treated more 

 fully belov/. As regards the mechanical raising of water however by ca- 

 pillary action it may be assured that the limit from which water can 

 make its way upwards, lies much higher than the limit accessible to 

 roots. All laboratorial experiments have shown that the upward movement 

 of water in dry soil due to the mechanical composition of the latter, is 

 comparatively very small for a given space of time — not more than a 

 few centimeters in coarse sand, and from 20 to 30 cm. in very fine soil. 

 In soil from the Odessa Experimental Field, sections of which were kept 



