Campbell's 1902 Soil Culture Manual. 



45- 



fundamental principles of agriculture, and application of those principles 

 to conditions which, exist in this semi-arid belt and no place else in our 

 country, that this region is to come into its rightful own and be made 

 indeed a veritable garden. 



CAPILLARY ATTRACTION. 



The capillary movement of moisture in the soil is a subject not well 

 understood, in fact, the average experience of the eastern farmer has not 

 demanded any knowledge on this subject, and the early experience of the- 

 inhabitants of the semi-arid belt did not call^for thought respecting this 

 matter. In short, among the masses of the farmers it is comparatively a 

 new proposition. One of the best illustrations to show the real facts in 

 connection with the movement of moisture in the soil, is that of glass 

 tubes, which we have frequently used in lectures to illustrate this point. 

 A tube about one-tenth of an inch in diameter will lift the water about 

 three-eighths of an inch above the surface. We have about a dozen, the 

 largest a tenth of an inch in diameter, the others smaller, all varying 

 in size down to as small a tube as can be drawn in glass, the smallest prob- 

 ably about one-hundredth part of an inch. In this the moisture will rise 

 about six inches above the surface of the water in which the tube is 

 placed. 



The first careful study of the rise of the water by capillary tubes was 

 made by Hauxbee nearly two hundred years ago, but history shows that 

 the phenomenon was known to Leonardo de Vinci, the famous artist, who 

 lived between 1452 and 1519. Notwithstanding the large amount of care- 

 ful study which these phenomena have received even during recent years, 

 we are yet in the dark as to just how the energy which forces the capillary 

 fluids to move is transformed into current motions, but all who have 

 studied the matter scientifically are agreed that it is in some way brought 

 about through the surface tension of liquids. Capillary movement is some- 

 what like electricity. We know its existence, we see its effects and have 

 learned something of the various conditions under which its power may be 

 utilized. Capillary movement of moisture, like electricity, has its field of 

 usefulness, and it is now quite apparent that this force within the soil 

 performs a most important ofiice in soil physics. 



Aside from the interest which the intelligent farmer will take in 

 this movement as a natural law, it should be thoroughly understood for 

 the especial reason that by capillary attraction the stores of water con- 

 served in the soil below the root bed are gradually lifted up to the roots, 

 as the plants may need the same for their sustenance and growth during a 



