CHAPTER XIX. 



SUB-IRRIGATION AXD SUBSOILIXG. 



Sub-irrigation is more of a theory than a condition, 

 and until it is better comprehended and more thoroughly 

 tested, the writer does not care to uphold it as a system 

 worthy of general adoption. There is no doubt that 

 sub-irrigation has many advantages, especially in the way 

 of economizing water, but the original cost of an under- 

 ground pipe system is so expensive that many men are 

 deterred from adopting it. A rough estimate would 

 make a gallon of water sufficient to irrigate a cubic foot 

 of ground, and this is a much higher duty of water than 

 can be obtained by the open trench system. 



This method is probably correct inprmciple, and 

 there are authorities who claim that it is most economic, 

 effective and wholesome. The prime aim, under any 

 system of cultivation, or irrigation, should be to stimulate 

 and induce capillary action in every possible way. It is 

 a fact, conceded by every observing cultivator of the soil, 

 that the finest and best crops and the most satisfactory 

 results in every way are obtained from those lands where 

 there is free, constant and uniform moisture diffused 

 from below. Soils differ with respect to the workings of 

 capillary attraction, but it is more or less potent in all 

 lands. The diffusion of moisture in this way will de- 

 pend mainly upon two conditions the supply received 

 or contained in the underlying strata, and the character of 

 the soil operated upon. Two other points closely allied 

 to these are the storage capacity underneath, and the 

 manner of cultivation. 



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