308 Peach-Growing 



but water must be abundant to permit of the successful 

 operation of this system. 



WHEN TO IRRIGATE 



The only true guide as to when water should be applied is 

 the moisture condition of the soil. In actual practice, where 

 an orchard is located on a party ditch, as is commonly the 

 case, a grower must use the water when his turn comes, or 

 at more or less regular intervals depending on the rules under 

 which the party ditch is operated or on the abundance of 

 water. 



While the soil-moisture conditions determine the proper 

 time for applying water, the grower learns in a measure to 

 correlate those conditions with the appearance of his trees. 

 There are certain conditions which should be avoided, the 

 most important of which are extremes of moisture. The 

 trees should never be allowed to become the least wilted 

 from lack of moisture and they should not be overirrigated. 

 The latter is a common tendency where water is abundant. 



Moisture exists in the soil in three forms or conditions, 

 hydroscopic, free, and capillary. Hydroscopic moisture is 

 that form in which it is so closely identified with the soil 

 particles as to be driven off only by a high degree of heat. 

 Dry road dust that is blown about in the wind contains 

 moisture in this form. It is of but little if any use to plants 

 in this form. 



Free moisture is the form in which water is so abundant 

 that it can be seen as such. It is subject to gravity and 

 passes off in drains, if the soil is provided with them. It so 

 fills the spaces between the soil particles that air cannot 

 enter. The chemical and biological changes and other 



