6 SURFACE- AND SUB-IRRIGATION 



the usual precipitation, or rainfall, as is the case in the arid 

 regions, for meteorological records show that the total rainfall 

 has varied very little from year to year ; but the cause of the 

 whole trouble is the irregularity of the distribution of rain. 

 This irregularity is attributed to various conditions, principal 

 among them, perhaps, being the destruction of forests. The 

 question now is: How can we best overcome these conditions? 

 Irrigation seems to be the only alternative ; hence we look to it 

 for a remedy. 



WHY DO WE IRRIGATE? 



By irrigation we mean supplying vegetation with moisture 

 when natural causes are not sufficient to produce the results 

 desired. It is mechanical interference with nature for definite 

 results. Until comparatively recent years few people east of 

 the Mississippi were interested in this subject ; the precipita- 

 tion, or rain-fall, was comparatively regular, and one year with 

 another was sufficient. The severe drouths, however, of the 

 past few years, which have been so persistent, have burdened 

 many people, and demand a remedy. People in some sections 

 have actually lost money, should their time be counted of any 

 value, in growing certain crops ; and in most sections this 

 drouth has materially cut crops short and therefore the profits, 

 for it is almost as much work and expense to grow a partial 

 crop as it is a full one. 



In the arid lands of the West where the evaporation exceeds 

 the precipitation, we easily see that irrigation must be resorted 

 to ; but this is not true of the East. Although in many states 

 we do not know the exact excess of precipitation over evapora- 

 tion, nevertheless the former is necessarily greater ; this is not 

 the point, however, for what we desire to secure is the even 

 distribution of rain-fall. In the years containing some of our 

 dryest summers, meteorological records show us that the aver- 

 age for the year is fully as great as in other years when the 

 summer seasons have been ideal. Knowing these facts, gar- 

 deners, fruit-growers, and in a few cases farmers, are studying 

 out remedies for themselves. It is not uncommon to see 

 question after question in our horticultural papers seeking 

 information on this subject. 



