FERTILIZERS AXD PLANT FOOD. 215 



Nitrogen is believed to come almost wholly from the soil, and the 

 ash also comes wholly from the soil. Thus it appears that the 

 elements from which the 12.51 ounces of starch, sugar, fiber, oil, 

 etc., were constructed came from the air and water; add to this 

 eighty-five per cent of the albuminoids and we get 13.79 ounces, 

 which with the 65.15 ounces of water gives us seventy-nine ounces 

 out of the eighty ounces total weight of the stalk, which came from 

 the carbonic acid of the air, and from the water of the soil ; this 

 water also comes from the air. The remaining ounce is made up 

 of eightj'-eight hundredths of an ounce of ash and twelve hundredths 

 of an ounce of nitrogen. With this ounce the study of feeding 

 plants commences, for nature provides the other seventy- nine 

 ounces free. 



The figures will be more valuable if we apply them to the product 

 of an acre of land rather than to a single stalk. 



The yield was twenty tons, or 40,000 pounds of corn as it was 

 cut for the silo. This amount contained the following: : 



Water . . . . 



Albuminoids, j Nitrogen. . . 



(756 lbs.) ( Carbon, hydrogen and oxygen, 



Fat 



f Cane sugar 



Carbo- j Glucose . 



hydrates, j Starch 



L Fiber 



Ash ' 



40,000 



The soil thus contributed 521 pounds of the total yield. It is 

 evident that the exhaustion of the fertility of the soil comes from 

 that portion of the crop which the plant takes from the soil and not 

 the elements taken from the air, and this question at once arises : 



In the particular case under consideration was it necessary to 

 supply the whole of the five hundred and ten pounds in order to 

 produce the crop? To answer this it will again be necessary to ask 

 the chemist to tell us what the ash of the crop was made [up of. 



