152 MASSACHUSETTS HORTICULTURAL SOCIETY. 



well as upon that which may be derived directly from the soil. In 

 the third place, the relation of fruit growing to soil exhaustion is 

 very different from that in general croj) farming, because in 

 orchards there is an annual demand for specific kinds and pro- 

 portions of soil constituents ; it is really a continuous cropping 

 of the same kind ; there is no opportunity, as in the case of 

 ordinary farm crops, to correct the tendency to exhaustion by a 

 frequent change of crops, or the frequent growth of those which 

 require different kinds and amounts of plant food constituents. 



Nitrogen, Phosphoric Acid, and Potash are the Ele- 

 ments NEEDED IN MANURES FOR ORCHARDS. lu Studying 



methods of manuring orchards, however, it must be admitted 

 that the general principles of manuring which apply to fruits, 

 appl}^ quite as well to farm crops ; that is, the essential con- 

 stituents of manures must be the same. A fruit tree will not 

 make normal growth in a soil destitute of nitrogen. That nitro- 

 gen encourages leaf growth is a recognized fact, and, since trees 

 grow by means of both leaf and root, its presence is required in 

 the soil in order to promote the growth and extend the life of 

 the tree. It is very evident, too, that potash is an essential con- 

 stituent in the growth of fruits, not only because it constitutes 

 a large proportion of the ash of the wood of the apple, pear, 

 cherry, and plum, and more than fifty per cent of the ash of 

 fruit, but because it forms the base of the well-known fruit 

 acids ; and in order to nourish a tree properly, as well as to 

 insure proper ripening, phosphoric acid is also very essential, 

 though it is apparent from such investigations as have been 

 made that this constituent is relatively of less importance than 

 for the cereals. 



It is also a matter of common observation that, in the produc- 

 tion of stone fruits particularly, lime is an important constituent. 

 Its function seems to be to strengtlien the stems and woody por- 

 tion of the tree, to shorten the period of growth, and to hasten 

 the time of ripening. Fruit trees growing on soils rich in lime 

 show a stocky, stead}^, vigorous growth, and the fruit ripens 

 well, while those on soils which contain but little lime, particu- 

 larly the clays, appear to have an extended period of growth, the 

 result of which is, that the wood does not mature and the fruit 

 does not ripen properly. 



The Need of Manures for Orchards. — It is argued by 



