212 SOILS AND FERTILIZERS 



soluble phosphate rock or some material of the same 

 nature. No. i is the most valuable, because it con- 

 tains the least insoluble phosphoric acid. This fer- 

 tilizer contains dissolved phosphate rock or dissolved 

 bone. No. 2 is composed of such materials as the best 

 grade of basic slag or roasted aluminum phosphate 

 or fine steamed bone. 



271. Potash. — The three forms of potash in fer- 

 tilizers are: (1) water-soluble, (2) acid-soluble, and (3) 

 insoluble. Materials as sulphate of potash, kainit, and 

 muriate of potash, which are soluble in water, be- 

 long to the first class. In some states the fertilizer 

 laws recognize only the water-soluble potash. In the 

 second class are found materials like tobacco stems 

 and the organic forms of potash. Substances like 

 feldspar, which contain insoluble potash, are of no 

 value in fertilizers. As a rule, the potash in commer- 

 cial fertilizers is soluble in water; in only a few cases 

 are acid-soluble forms met with. Insoluble potash 

 would be considered an adulterant. 



272. Misleading Statements on Fertilizer Pack- 

 ages. — Occasionally the percentage amounts of nitro- 

 gen, phosphoric acid, and potash are stated in mis- 

 leading ways as ammonia, sulphate of potash, and 

 bone phosphate of lime. Inasmuch as 14/17 of am- 

 monia is nitrogen, the percentage figure for ammonia 

 is proportionally greater than the nitrogen. And so 

 with sulphate of potash which contains about 50 per 



