392 



State Horticultural Society. 



RELATIVE PROPORTIONS OF PLANT FOOD CONSTITUENTS USED BY BEARING 



TREES. 



It will be noted that these proportions apply to the food require- 

 ments for trees in full bearing, and represent the food necessary not 

 only for the development of the fruit, but of the leaf and twig- growth. 

 It will be observed that there is very little difference between the dif- 

 ferent kinds, all requiring plant food in quite similar amounts. 



This means, of course, that as far as the chemical composition of a 

 fertilizer is concerned, it would be quite as well adapted to one fruit 

 as to another. 



AMOUNTS O'F PLANT FOOD REMOVED PER ACRE BY BEARING TREES. 



It is impossible to supply data on this point applicable to all classes 

 of trees and to all seasons. In other words, it would be exceedingly 

 difficult to find a number that would apply to the average season and 

 soil. When it is realized that of the total plant food required to nourish 

 a tree during the season, including the wood growth, the crop of leaves, 

 and the crop of fruit when the tree is in full bearing, some 79 per 

 cent of the dry matter formed by the tree is in the fruit pulp, in the case 

 of the apple, about 19 per cent in the leaves, and 2 per cent in the new 

 growth, and that in general the fruit requires about half of all the plant 

 food used by the tree during the growing season, it is obvious that the 

 size of the fruit crop will afifect very materially the amount of plant food 

 used. 



On the other hand, during a season when a tree is bearing a heavy 

 fruit crop, there is, as is well known, a comparatively small amount of 

 new wood formed, and the requirements of plant food for this purpose 

 are in such a season very small indeed. Yet in seasons of crop failure 

 or when very little fruit is borne, there is a relatively large wood growth, 

 except when it is too dry, so that the tree draws more heavily upon the 

 soil for this particular purpose in such a year than when it is carrying 

 a full load of fruit. 



