Winter Irrigation of Deciduous Orchards. 221 



tion, the soil in the cultivate:! area would be found to. contain 

 about twice as much available moisture as that in theuncuiti' ated 

 area. Or to make the statement in another form, the loss of water 

 from the uncultivated area from March 5 to May 23 exceeded the 

 loss from the cultivated area by the equivalent of over two inches 

 of rainfall ; and the loss during the entire summer would probably 

 be about three times this amount. To replace this loss from a 

 ten-acre field would necessitate the running of a stream of 2 « ■_. 

 second feet (100 miner's inches) for about 30 hours. 



In order to produce the best results the soil must be so culti- 

 vated, however, that it is not left broken up into large clods, that 

 will permit the air to reach the underlying strata. The finer and 

 looser the surface mulch the better, and in our arid region it needs 

 to be deeper than elsewhere. 



Weeds injure growing crops by appropriating the available 

 plant food and by removing water from the soil. While a soil 

 may be very fertile, there seldom is present enough plant food, in 

 the form necessary for the use of plants, to support a crop of 

 weeds and a crop of fruit. But weeds usually do the greatest in- 

 jury by removing water from the soil. Not only do weeds require 

 water for their increase in size, but water is continually evaporat- 

 ing from the surface of their leaves. While they may shade the 

 surface of the soil so as to check evaporation there, the evapora- 

 tion from their leaves is much more rapid than it would be from 

 the surface of the unshaded soil, if it were properly cultivated. 



One Summer Irrigation Considered .Advisable. 



If about the middle of the summer, water is available in 

 abundance, it would probably be wise to give the orchard a thor- 

 ough irrigation in as short a time as possible, and then follow the 

 irrigation with a thorough plowing, as in the spring after the 

 winter-irrigation ceases. But frequent summer irrigations are 

 decidedly not advisable under our conditions, where the soil is 

 fairly deep and retentive of moisture. 



