CHAPTER II 



THE CONDITIONS WHICH MAKE IRRIGATION IMPERA- 

 TIVE, DESIRABLE OR UNNECESSARY 



To understand the conditions which make it im- 

 perative, desirable or unnecessaiy to irrigate land, it 

 is important to have clearly in mind the various objects 

 which may be attained by the application of water to 

 cultivated fields. 



THE OBJECTS OF IRRIGATION 



The first and primary object to be attained in irri- 

 gating the soils of arid climates is to establish those 

 moisture relations which are essential to plant growth, 

 and the same fundamental object will usually stand 

 first in sub -humid climates, as it may even in those 

 which are distinctly humid ; for in the sub -humid 

 climates it very often happens that the intervals 

 between rains of sufficient quantity are so long that 

 almost any crop may suffer ; and in humid climates 

 there are certain crops, like the cranberry and rice, 

 which profit by more or less protracted inundations ; 

 or, again, like the pineapple, growing upon extremely 

 leachy sands, which can retain but a small quantity 

 of water even for a single day, and where it is neces- 



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