198 Fertilizers 



of the crop itself, whether the value of an increase in crop 

 as great as can be expected from a definite application is 

 high or low; and on this basis, crops may be classified 

 into two general groups : first, those which possess a high 

 fertility, and which, as a rule, possess a relatively low com- 

 mercial value ; and second, those which possess a low fer- 

 tility value and a relatively high commercial value. In the 

 first class are included the cereal and forage crops, as corn, 

 oats, wheat, hay, buckwheat, cotton and tobacco, and in 

 the second are included the various vegetable and fruit 

 crops. This classification, and its importance, may be 

 illustrated by the following examples : 



A ton of wheat, at $1 a bushel, will bring $33.33. Its 

 sale removes from the farm 38 pounds of nitrogen, 19 of 

 phosphoric acid and 13 of potash. At prevailing prices 

 for these constituents, it would cost $6.50 to return them 

 to the farm. 



A ton of asparagus shoots, at 10 cents a pound bunch, 

 will bring $200. Its sale removes from the farm 6 pounds 

 of nitrogen, 2 of phosphoric acid and 6 of potash, which 

 could be returned for but little more than $1. 



A ton of timothy hay will bring $14. Its sale removes 

 from the farm 18 pounds of nitrogen, 7 of phosphoric 

 acid and 28 of potash, amounts that would cost $4. 



A ton of apples will bring in an ordinary season $20. 

 It removes less than 3 pounds of nitrogen, 1 of phosphoric 

 acid and 4 of potash, which would cost less than 60 cents 

 to return to the land. 



It is thus shown that crops like wheat and hay possess 

 a relatively low commercial value, and yet carry away, 

 when sold, a very considerable amount of the fertilizing 

 constituents, while vegetables and fruits, as illustrated by 

 the asparagus and the apples, have a high commercial or 



