COMMERCIAL FERTILIZERS 31 



Phosphorus may be bought in rock phosphate, or bone meaL 

 Either may be bouglit in the raw or in the ''treated" form. Rock 

 phosphate or bone that has been treated with acid contains its 

 phosphorus in a more quickly avaihible form than th(^ raw material, 

 but its continued use is likely to have an undesirable effect upon 

 the soil. Steamed bone meal is an especially desirable form in 

 which to apply phosphorus for vegetable crops. It acts quickly 

 and does not injun^ the land. 



Sources of Potassium. — The principal commercial sources of 

 potassium are muriate of potash, sulfate of potash and unleached 

 hard-wood ashes. Where ashes can be procured, they constitute 

 one of the best sources of potassium. They act quickly, and do 

 not injure the plant or the soil. The percentage of potassium they 



r 



contain is rather low, so that they may be used much more freely 

 than either muriate or sulfate of potash. Sulfate of potash is 

 considered more desirable than the muriate for certain crops. Pota- 

 toes, for example, are claimed to be of better quality when fertil- 

 ized with the sulfate rather than the muriate of potash. 



Purchasing Fertilizers. — Commercial fertilizers can be bought 

 by the ton or the carload at any time of the year. They are con- 

 centrated, so that enough plant food for ten acres of ground can 

 be stored in a small space. They are in condition to apply at 

 any time, and modern machinery makes their application a simple 

 matter. 



Effects on Soil. — So far as plant food is concerned, com- 

 mercial fertilizers furnish the same elements as are contained in 

 animal manures. Yet their continued use, to the exclusion of 

 animal manures and green manures, will lead to disastrous results. 



