AMOUNT OF WATER MOVED 185 



89. Examples of the amount of water moved. In 

 crop production, the crucial test of the capillary capacity 

 of the soil is the amount of water it is able to move. 

 It must not only be able to move water a long distance, 

 or to a great height, but it must be able to move a rela- 

 tively large amount of water, and to move it quickly 

 if the movement shall be effective. The important 

 consideration is the amount of water moved a given 

 distance in a given time. A soil may be able to quickly 

 move large volumes of water to a height of a foot, 

 and be utterly ineffective to a height of five feet. On 

 the other hand, a soil may be so fine as to be able to 

 lift water to a height of forty feet, and yet the move- 

 ment be so slow and the amount of water moved be 

 so small that the result is negligible, that is the soil 

 is capillarily ineffective. It therefore appears that, 

 for any given distance within reason and for any normal 

 moisture demand of a crop, there is a texture and struc- 

 ture of soil which will most readily meet those demands. 

 If the water-table is three feet below the surface, a 

 very coarse soil may suffice. If the water-table is ten 

 feet below the surface, a much finer soil will be necessary. 

 On the other hand, to supply a full-sized pumpkin vine, 

 having a large evaporation, from a water supply five 

 feet away, will require a finer soil than is required 

 to supply a Jersey pine having a small evaporation. 

 In other words, we need to know the effective capillary 

 capacity of each soil to different heights and distances, 

 up to their limits. 



Very little data of this sort is available. None is 

 available for horizontal movement, and the figures 



