310 Bureau of "Farmers' Institutes. 



into the total cost, that is, the retail cash cost in the market of 

 unmixed raw materials. 



Valuation and Agricultural. Value. — The agricultural 

 value of a fertilizer depends upon its crop-producing power. A 

 commercial valuation does not necessarily have any relation to 

 crop-producing value. For a particular soil and crop, a fertilizer 

 of comparatively low commercial valuation may have a higher 

 agricultural value; while for another crop on the same soil or the 

 same crop on another soil the reverse might be true. 



Simple Rule for Calculating Approximate Commercial 

 Valuation of Fertilizers. 



Multiply the per cent, of nitrogen by three and add to the prod- 

 uct the figures representing the per cent, of available phosphoric 

 acid and of potash. The sum expresses in dollars and cents the 

 approximate commercial valuation of the fertilizer. 



Example. — A fertilizer contains Per cent 



N itrogen 4.13 



Available phosphoric acid 8 . 52 



Potash 10.54 



4. 13 (per cent, of nitrogen) multiplied by three, equals, $12 39 



8.52 (per cent, of available phosphoric acid) 8 52 



10 . 54 (per cent, of potash) 10 54 



Total, per ton $31 45 



If a fertilizer contains only one or two of the three essential 

 fertilizing ingredients, the rule can be applied in a modified form. 

 In case of fine bone meal, use the total phosphoric acid in place 

 of the available in making the calculation. 



While this rule is not exact, it gives results that are fairly accu- 

 rate and has the great advantage of simplicity. Results obtained 

 by this rule will be somewhat higher than those given by the 

 Linger method of calculation. It will be found satisfactory com- 

 monly in making comparison of different mixed fertilizers. 



For the benefit of those who desire a more exact method of 

 calculating the commercial valuation of fertilizers, we give below 

 a more detailed rule. But previously we give methods for cal- 

 culating from one compound to another, and also methods for 

 making valuations of unmixed fertilizing materials. 



