28 



FERTILITY AND FERTILIZER HINTS 



is usually lost than the crop removes. The following table il- 

 lustrates this point. ^ 

 Loss OF Nitrogen by Continuous Cropping Per Acre Per Year. 



Name of Crop. 



Nitrogen removed 

 by crop. 

 Pounds. 



Nitrogen lost by 



other means. 



Pounds. 



Total nitrogen re- 

 moved and lost. 

 Pounds. 



Wheat 

 Corn . . 

 Oats . . 

 Barley 



24-5 

 56 

 46 

 30 



146.5 

 29 

 150 

 170 



171 



85 

 196 

 200 



The loss of nitrogen by continuous cropping of cotton, corn, 

 tobacco and the cereal crops is a very serious one. 



Loss of Phosphoric Acid and Potash. — Although phosphoric acid 

 and potash are usually present in the soil as compounds insolu- 

 ble in water, nevertheless large quantities are lost every year 

 by being carried away with the soil into rivers and other streams. 

 Again, traces of phosphoric acid and potash are carried away in 

 the soluble form by drainage and although this loss is not large 

 per acre it amounts to a great deal in the course of time. 

 The Mississippi River deposits in the Gulf of Mexico 3,702,- 

 758,400 cubic feet of solid material per year. One cubic foot 

 of this solid material weighs about 80 pounds. This material 

 is quite rich in potash often containing as high as 0.50 per cent, 

 of this constituent. The phosphoric acid content is much lower 

 than this figure but is considerable. The rivers that empty 

 into the oceans in the northern part of the United States do not 

 perhaps carry away so much fertility as the rivers of the far 

 south, but the annual loss of the mineral elements carried away 

 in streams is appalling. 



One Crop Farming. — The exclusive growing of one crop caused 

 more farms to be abandoned in the United States than any other 

 practice. The continuous cropping of wheat in the West, to- 

 bacco in Kentucky, Virginia and North Carolina, cotton in the 

 South, and corn in the North Central States has always re- 

 sulted in the loss of fertility and depletion of the soil. All of 

 these crops with the exception of corn are sold from the farm 



1 Bui. 5'v Minnesota Experiment Station. 



