396 State Horticultural Society. 



The notion that a bearing orchard requires an insignificant quantity 

 of plant food as compared with the ordinary farm crops is shown by 

 this table to be entirely wrong. In fact, apple trees bearing a normal 

 crop require for fruit leaves and new wood more pounds of each of 

 tlie three commercial elements of plant food, viz. : nitrogen, potash and 

 phosphoric acid, than a 30-bushel crop of corn for the grain and stalks, 

 and very much more than a 15-bushel crop of wheat and its accompany- 

 ing straw. 



MAKING THE PLANT FOOD IN THE SOIL AVAILABLE. 



As is well known, only a small portion of the plant food contained 

 in any gopd soil is at any one time available to growing crops. The 

 processes which render this plant food available are going on more or 

 less actively, practically all the time. The rate, however, at which this 

 food is made available to the growing tree will vary according to the 

 season and to the method of treating the soil. 



For example, during an excessive wet season, when the soil is 

 either water-logged or being leached much of the time, there is unlocked 

 in the soil a relatively small amount of plant food, and much of that 

 which was already made available is lost either temporarily or perma- 

 nently through the processes of leaching. This means that the soil 

 should be watched carefully the year following an excessively wet sea- 

 son. This is particularly true if the trees following such a season happen 

 to set a large crop of fruit. 



Then, during a very wet season, the soil solutions are so diluted that 

 the trees will actually find less plant food and have greater difficulty in 

 getting that which they do find. 



Likewise, in a very dry season the chemical and biological changes 

 are very much retarded, owing to the absence of moisture. Neverthe- 

 less, it should be remembered that in such a season the movement of 

 soil moisture is upward from great depths, and large quantities of mois- 

 ture are brought to the surface and vaporized. The plant food that 

 had in wet seasons been carried beyond the depths of the ordinary grow- 

 ing crop is brought by this upward movement of the water to the 

 surface and by the vaporization of the water deposited there in a readily 

 soluble form. This does not mean, however, that the plants derive bene- 

 fit from these salts during the drouth, for there is not sufficient moisture 

 in the soil to make this possible. Therefore, while a dry season does 

 not favor the breaking down of the plant food compounds in the surface 

 soil, it does in fact favor the accumulation of this soluble plant food in 

 the surface soil, by bringing it from great depths, and also by the limited 



