Plant -food Consumed by Apples. 205 



"These investigations, when considered in all their 

 hearings, lead one to wonder not why old orchards 

 are failing, but why they have not ceased to pro- 

 duce merchantable fruit long since." 



Another calculation by the same investigator 

 shows the amount of plant -food which may be ex- 

 pected to be carried away in the fruit, and blown 

 off in the leaves (not computing the amount in the 

 wood), for the period between the ages of 13 and 

 .'53 years of apple trees : 



Apples. Leaves. Value. 



" Nitrogen 498.60 Ibs. 450.75 Ibs. $143.30 



Phosphoric acid 38.25 " 126. " 11.50 



Potash 728.55 " 441. " 52.63 



Total value $207.45 



" While the above results are reached by assum- 

 ing a given amount of apples and leaves per year 

 in a bearing orchard, and while the facts in any 

 given case at any given time may vary widely, yet 

 it is believed that they are valuable, as they fur- 

 nish a means of measuring in any given case, with 

 a great degree of accuracy, the amount of soil ex- 

 haustion." 



He also "shows that an average crop of apples 

 removes in round numbers eleven pounds of nitro- 

 gen, nearly one pound of phosphoric acid and six- 

 teen pounds of potash, and that the leaves of a 

 tree large enough to produce the apples would con- 

 tain ten pounds of nitrogen, nearly three pounds of 

 phosphoric acid and ten pounds of potash, or a total 



