FIGURING FERTILIZERS 49 



The sum of these 4 products will be the commercial valuation per 

 ton on the basis taken. 



Illustration. The table of analyses shows a certain fertilizer to have 

 the following composition: Nitrogen 2.52 per cent; available phos- 

 phoric acid 6.31 per cent; insoluble phosphoric acid .89 per cent; 

 potash 6.64 per cent. According to this method of valuation, the 

 computation would be as follows : 



Nitrogen 2.52 X 4.0 = $10.08 



Available phosphoric acid . 6.31 X 0.8 = 5.05 



Insoluble phosphoric acid 0.89 X 0.4 = 0.36 



Potash 6.64 X 1.0 = 6.64 



$22.13 



This rule assumes aM the nitrogen to be organic and all the potash 

 to be in the form of sulfate. If a considerable portion of nitrogen exists 

 in the fertilizer as nitrate of soda or as sulfate of ammonia, and potash 

 is present as muriate, the results are somewhat less. 



Farmers should be warned against judging fertilizers by their valua- 

 tions. A fertilizer, the cost of which comes chiefly from the phosphoric 

 acid present, would value much lower commercially than a fertilizer 

 with a high percentage of nitrogen, and yet the former might be the 

 more profitable for a given farmer to purchase. 



Table for converting the fertilizer elements into their usually reported forms, 

 and vice versa (J. P. Stewart) 



(a) CONVERTING ELEMENTS INTO COM- (&) CONVERTING COMPOUNDS INTO ELE- 



POUNDS -fc "- MENTS 



K X 2.4103 = K 2 O. K 2 O X .4149 = K. 



P X 4.5806 = P 2 O 5 . P 2 Os X .2183 = P. 



N X 1.2143 = NH 3 . NH 3 X .8235 = N. 



Mg X 1.6667-= MgO. MgO X .6000 = Mg. 



Ca X 1.4000 = CaO. CaO X .7143 = Ca. 



Computing the trade value. 



A simple way of figuring the value of a commercial fertilizer l (Cavanaugh) 

 EXAMPLE No. 1. GUARANTEED ANALYSIS 



Nitrogen 1.60 to 2.00 per cent 



Phosphoric acid available 7.00 to 8.00 per cent 



Potash 2.00 to 3.50 per cent 



Cost per ton $29.00 



1 In these and the succeeding examples, it happens that the trade values per 

 Ib. of chemicals are not those of 1910, given on pp. 47-48 ; but it is intended 

 only to explain the method. 



