66 APPLE GROWING IN CALIFORNIA. 



in an experimental way by W. H. Volck at Watsonville. The results 

 that he has attained have on the whole been excellent, and this method 

 of applying nitrates bids fair to come into general use. 



Many of our California soils are deficient in lime and the addition 

 of either air slaked or ground stone lime might be beneficial. Xo rules 

 can be laid down for this work because of the great varieties of soil 

 that occur in the state. If trees are not doing well it may be that 

 fertilizers of some kind are needed. A soil analysis will serve as a 

 guide as to what should be added, but must not be depended upon too 

 much, for while it shows what elements of plant food the soil contains, 

 and the proportions of each present, it does not show how much of each 

 is available, so after all much experimental work is necessary. 



As stated previously, nitrates are nearly always scarce and fertiliza- 

 tion usually means the addition of the element nitrogen, either in the 

 form of leguminous cover crops grown in the soil, or mineral nitrates 

 applied direct or in the form of a spray to the trees. 



