THE USE OF FERTILIZATION IN APPLE ORCHARDS. 



Dr. J. P. Stewart, Experimental Pomologist, State College, Penna. 



The proper fertilization of an orchard is largely a local prob- 

 lem. It is no less a problem, however, because it is local. The same 

 is true, to a marked extent, of many other orchard operations, not 

 excepting cultural methods. It is true that of late it has become a 

 fashion among horticulturists to assume that the whole truth is 

 known about cultural methods, that there is but one proper method 

 for orchards and that all growers who do not follow it are either 

 shiftless or ignorant. But the fact is, that even with cultural meth- 

 ods, the practice found best for one particular soil or location, or 

 for one age of orchard or fruit effect, is by no means certain to be 

 best for all others or even the best for the adjacent farm. In gen- 

 eral, therefore, it appears that there are at the present time, com- 

 paratively few horticultural principles or practices which are really 

 exact and general in their application. Most of them seem to be 

 quite subject to important exceptions, and hence usually they re- 

 quire some local modification or adjustment, if the best results are 

 to be secured. 



So it is with orchard fertilization. We know that it is likely 

 to be important and we can now give approximate general direc- 

 tions for it. But w^hen we come to the actual fertilization of a par- 

 ticular orchard, some local tests and local adjustments are usually 

 desirable. 



The Amounts of Plant Food Actually Taken up by a Mature 



Orchard. 



That there is an important need for fertility in any orchard 

 that is actively producing and growing, there can be no reasonable 

 doubt. The actual extent of this need can be approximated chem- 

 ically by determining the average composition of apple wood, leaves, 

 and fruit, and applying these figures to what may be considered 

 good annual amounts of these three products. This we have done 

 both for apples and for a 25-bushel crop of wheat, with the results 

 shown in Table I. The annual weights for apples are based on a 

 yearly production of 100 pounds each of wood and leaves and 14 

 bushels of apples per mature tree. All these amounts are distinctly 

 less than those actually observed and reported, but inasmuch as they 

 give an annual yield of 490 bushels per acre of 35 trees, they are 

 considered sufficient for the present purpose. 



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