COMMERCIAL FERTILISERS 369 



What a lot of dust-raising! Doubtless it is all 

 true; and the manufacturer nas complied with the 

 law that requires him to state on the tag the amount 

 of plant food contained in the fertiliser. But the 

 buyer wants to know just one thing how much 

 available potash, phosphoric acid, and nitrogen 

 the fertiliser contains. This tag should have 

 read? 



Percent. 



Soluble phosphoric acid 10 



Reverted phosphoric acid 2 



That is all there is in it of value to the farmer. 

 The most reliable manufacturers print on their tags 

 a bare statement of the amount of actual plant 

 food the fertiliser contains. 



Repetitions in Guarantees. Another fertiliser 

 tag reads: 



Per cent. 



1. Ammonia 3 to 5 



2. Available phosphoric acid 11 to 13 



3. Total phosphoric acid 15 to 19 



4. Total bone phosphate 27 to 30 



5. Actual potash 12 to 14 



6. Muriate of Potash 18 to 22 



There are several repetitions in this complete 

 fertiliser. Contrary to the common idea among 

 farmers, ammonia is not nitrogen; it is only four- 

 fifths nitrogen, the other fifth being hydrogen, 

 which has no value as a fertiliser. It will be 

 necessary to multiply the 3 per cent, of ammonia 

 by .82, the actual percentage of nitrogen in am- 

 monia. This shows that there is 2.46 per cent, of 

 the plant food nitrogen in this fertiliser, instead 

 of 3 per cent. There is 11 per cent, of available 



