108 SOILS AND FERTILIZERS 



available as plant food. 44 A soil with 5,000 pounds 

 of total nitrogen per acre would contain about 100 

 pounds of available nitrogen, of which only a part 

 comes in contact with the roots of crops. Hence, it 

 is that a soil may contain a large amount of total 

 nitrogen, and yet be deficient in available nitrogen. 



128. Amount of Nitrogen Removed in Crops. 

 The amount of nitrogen removed in crops ranges from 

 25 to 100 pounds per acre depending upon the nature 

 of the crop. It does not necessarily follow that the 

 crop which removes the largest amount of nitrogen 

 leaves the land in the most impoverished condition. 

 Wheat and other grains, while they do not remove 

 such a large amount of nitrogen in the crop, leave the 

 soil more exhausted than if other crops were grown. 

 This, as will be explained, is caused by the loss of 

 nitrogen from the soil in other ways than through 

 the crop. 38 



Pounds of nitrogen 

 per acre. 



Wheat, 20 bushels 25 



Straw, 2,000 pounds 10 



Total 35 



Barley, 40 bushels 28 



Straw, 3,000 pounds 12 



Total 40 



Oats, 50 bushels 35 



Straw, 3,000 pounds 15 



Total 50 



Flax, 15 bushels 39 



Straw, i ,800 pounds 15 



Total 54 



Potatoes, 150 bushels 40 



Corn, 65 bushels 40 



Stalks, 3,000 pounds 35 



Total 75 



