THK REIvATlON OF SOILS TO IRRIGATION. 3 1 



servient to the agriculturist. Some authorities claim 

 that soils which have been cropped until the soluble 

 ingredients, organic elements, and humus have been 

 materially decreased retain less water and dry out 

 more readily than when there is a larger amount of 

 organic matter present in the soil. This depletion, 

 however, may easily be obviated by the scientific 

 application of fertilizers, the growing of nitrogenous 

 plants, or by crop rotation. 



Capillary Action. — In concluding our observa- 

 tions on this important topic of soils the matter of cul- 

 tivation must not be overlooked. The success of irri- 



FIG. 5 — CAPILLARY TUBES OF SOIL. 



gation cannot be made complete without cultivation, 

 and it is a fault too commonly observed among irriga- 

 tors that they are inclined to depend too much upon 

 irrigation and not nearly enough upon cultivation. 

 The retention of the moisture when once supplied to the 

 soil by means of irrigation may be largely controlled by 

 keeping the topsoil well pulverized, so as to break up 

 the capillary tubes, as shown in Fig. 5, a being the sur- 

 face, b the capillary tubes, and c the subsoil. The more 

 recent scientists all agree that the soil is full of small 

 tubes, through which the moisture from below finds its 

 way to the surface and escapes. If these tubes can be 

 closed the water will not evaporate so readily. This 



