HOW TO APPLY WATER 163 



water in large amounts very cheaply. Not only is there danger of over- 

 irrigation in the growth of tree and fruit, but the ill effects of water 

 upon the soil, when unattended by good cultivation, are constantly 

 threatened. The tree needs air as well as water ; it needs a certain free 

 condition of the soil for its best root action. These needs can be amply 

 secured when adequate application of water is quickly followed by 

 soil-stirring. Irrigated soil rightly treated is delightfully mellow and 

 free and of condition to invite the fullest activity on the part of the tree. 

 Irrigated ground not properly treated becomes compacted, fissured, 

 cloddy and generally hateful, losing moisture rapidly, setting around 

 the roots like cement and tearing them by its subsequent shrinkage. 

 These conditions do not occur on the lighter soils, and yet even these 

 are best when cultivated in a rational manner. 



METHODS OF IRRIGATION 



There are various methods employed in California for the convey- 

 ance and application of water to trees and vines. Some of the principal 

 ones will be described. 



As this writing does not pretend to be a treatise on irrigation engi- 

 neering, no -attempt will be made to describe the more ambitious under- 

 takings, which should never be entered upon without the engagement 

 of a qualified engineer. Nor is it possible to discuss the numerous 

 devices which are covered by patents. Investment should always be 

 preceded by visits to irrigation works now in operation, and procedure 

 should be guided by observation. The hints presented herewith relate 

 chiefly to things the irrigator can. do for himself. 



Free Flooding. Flooding that is, the free flow of water over 

 the whole surface, or the flow between rows with furrows near the 

 trees to retain the water in the interspaces is only employed on some 

 flat lands where winter irrigation is used to supplement rainfall when 

 the latter is occasionally below normal. In such cases water is available 

 in large quantities, and the lay of the land favors quite even distribu- 

 tion. Even under these conditions the experience of growers soon 

 leads to the adoption of deep furrows or lateral ditches, or some simple 

 check system, as superior to flooding. Summer flooding is done only 

 by those who are unacquainted with better methods or who count their 

 trees of too little account to warrant extra effort. It seems, therefore, 

 a fair conclusion that flooding is only resorted to as a temporary expe- 

 dient, and has little standing. 



The Check System. With soils of such character that vertical 

 percolation is very rapid, flooding in checks, by which water is held 

 upon a particular area until it sinks below the surface, is considered 

 necessary. There is a tendency to change from this method to a furrow 

 system wherever practicable, because the former requires more soil 

 shifting, a larger head of water for economical operation, more labor 

 to handle it, more working in water and mud, and more difficult culti- 

 vation to relevel the land and to reduce a puddled surface to satisfactory 

 tilth. For these and other reasons, perhaps, on loams of medium fine- 



