— 19 — 



How the process of the upward transference of water in the soil 

 is carried on, under conditions of a non-saturated soil, and in the ab- 

 sence of an available sourse of water in the immediate vicinity that is 

 to say whether the water gets to the top in a liquid or in a state of 

 vapour-it would be difficult to say with certainty in the present state of 

 this question with its lack of precise evidence founded on fact. 



But there is one consideration which tells in favour of the mo- 

 vement taking place in a state of vapour and not in the state of liquid drops. 

 It is the following: — the so called capillaries in dry soil form an extre- 

 mely irregular network of hollow spaces of various, size and shape. They 

 do not resemble in any way those glass capillaries or tubes which 

 are used for experimental purchases in the laboratory and with which 

 they are usually compared. For the glass walls of these tubes prevent 

 any air from entering from the sides, a condition which does not exist 

 in the soil; and for that reason the condition of water circulat'on in so;l 

 contained in glass tubes will be different from that in the soil of open 

 fields, In a strict sense, capillaries or „tubes" as some authors call them, 

 no more exist in the soil than they do -to give a familiar example — in 

 a heap of small-shot of various sizes, which, with their interstices, may 

 be compared to the soil. -- When the soil is not fully saturated with 

 water — and this is always the case in fields — a certain proportion of the 

 interstices between the particles are filled with air. and the others with 

 water; in consequence of which water is found in these interstices :n the 

 form of separate drops cut off one from an other by air. If under any 

 circumstances whatsoever an upward movement appeared in a signifi- 

 cant thickness of soil, that movement could only concern the more mo- 

 bile parts viz: the air, which circulates in the free empty spaces not 

 taken up by water — and the drops of water could remain where they 

 are: or because of their weight sink downwards. All these considerat'ons, and 

 the absence of facts to the contrary, lead to the conclusion that an up- 

 ward movement of v/ater only goes on in soils saturated with water; 

 whereas those in a non saturated condition suffer a loss of water whe- 

 rever a drop lies, by evaporation in the air surrounding that drop. For 

 this reason the loss of water in the superficial soil layer goes on very 

 slowley even when the layer is in a compact condition, Campbell's sys- 

 tem so much spoken of latterly, will not bear criticism in regard to its 

 main thesis: — increasing the capillary process in deep soil layers and 

 leading water from them up into those layers near the surface. 



Compression with the subsoil roller causes the soil particles to 

 adhere closely, expels the air from their interstices, at the same time 

 satiating this compressed layer with water — and nothing more. It cannot 

 be doubted that the conditions for the growth of seeds, sown on such a 



