COMMERCIAL FERTILIZERS IN GENERAL 



205 



Mixed Fertilizers. — Commercial fertilizers containing mtrogen, 

 phosphorus and potassimn aie called mixed fertilizeis. Those 

 containing all thiee of the feitihzmg elements aie called ^^ com- 

 plete '^ fertilizers. In this respect, manure is to be regarded as a 

 complete fertilizer. 



Hunclieds of brands of mixed commercial fertilizers aie to be 

 found on the maikct — sold under various trade names ^ such as, 

 Corn and Cotton Grower, Dieadnought Fertiliser, Pacific Crop 

 Producer, etc. These fertiHzers are commonly spoken of in terms 

 of the per cents of the fertilizing constituents contained in them; 

 for example, a mixed fertilizer containing two per cent ammonia 

 (NH3), twelve per cent phosphoiic acid (P2O5) and two per cent 

 potash (K2O) is called a '^2-12-2^^ fertihzer.s A '^ 0-12-4^' fertil- 

 izer means one containing no ammonia (NH3), twelve per cent 

 phosphoric acid (P2O5) and four per cent potash (K2OV. 



The following shows the meaning of some mixed fertilizers 

 in terms of the elements: 



Per cent 

 ammonia 



(NH-j) 



Per cent 

 phosphoric 

 acid (P Oa) 



Per cent 



potahh 



(KO) 



Per cent 

 nitrogen 



(N) 



Per cent 



phosphoi us 



(P) 



Per cent 



potassium 



(K) 



4 

 2 

 



8 

 12 

 10 



4 

 2 



8 



33 

 15 

 



35 



52 

 44 



33 

 17 



66 



Use of Mixed Fertilizers. — Mixed fertilizeis aie very generally 

 used. Applications vaiy from 50 to 1500 pounds and more to the 

 acre. It is better to purchase these fertilizers on the basis of what 

 they contain lather than because of their names. 



Commercial Fertilizers in General. — Many erroneous ideas 

 are pievalent regaidmg the use of commeicial fertilizers, especially 

 in sections where fertiHzers are little used or practically unknown. 

 Some believe they injure the soil, and that when once used their 

 use must be continued. It is not because the ''soil gets a bad 

 habit '' that many farmers continue the use of fertilizers, but be- 

 cause of profitable leturns. Fertilizers sometimes fail for the 

 following reasons: The wrong kind of fertilizer may have been 

 used; it may have been applied in the wrong manner; the soil 

 may lack proper underdrainage, and there may have been a 

 deficiency of moisture. 



^ In some Southern states phosphoric acid is usually mentioned first, then 

 ammonia and potash A '10-4-3" fertilizer m those states means, therefore, 

 10 per cent phosphoric acid, 4 per cent ammonia and 3 per cent potash. 



