68 FUNDAMENTALS OF AGRICULTURE. 



phosphoric acid and potash. From these market 

 prices he makes out a schedule of values to cover the 

 average cost of nitrogen, phosphoric acid and potash. 

 Suppose, for instance, the chemist fixes the following as 

 the values Nitrogen 16 cents a pound, available phos- 

 phoric acid 5 cents a pound and potash 5 cents a 

 pound. Then a fertilizer guaranteed 10 per cent, 

 available phosphoric acid, 2 per cent, nitrogen and 2 

 per cent, potash, is worth, $18.40 a ton, since, 



Ingredients, per ton Ibs. "*;?' 

 per ID 



Available phosphoric acid . 10% of 2000 = 200 Ibs. 200 x $ . 05 = $10 . oo 



Nitrogen 2%of2OOO= 40 Ibs. 4ox .16= 6.40 



Potash 2% of 2000 = 40 Ibs. 40 x .05 = 2 .00 



Commercial value per ton = $18.40 



The values adopted by the chemists generally repre- 

 sent the wholesale cost of fertilizer materials. The 

 values are given so as to enable the purchaser to ar- 

 rive at some conclusion concerning the commercial 

 value of fertilizers. These values do not take into 

 account the freight, business losses, cost of manufac- 

 ture, and manufacturer's profit. Hence the selling 

 prices of fertilizers are somewhat higher than would 

 be estimated from the chemist's values. 



Agricultural V alue of Fertilizers. The commercial 

 value of a fertilizer should not be taken as its agricul- 

 tural value in all cases. The commercial value gives 

 the cost of a fertilizer, while the agricultural value 

 shows the worth of a fertilizer for producing crops. 

 To determine the agricultural value of a fertilizer, 

 the farmer must experiment in the field. 



EXERCISE. Is there a fertilizer law in your state? If there is such 

 a law and your parents haven't any fertilizer at home, go to the 

 store where fertilizers are sold and copy in your note-book the 

 printed guarantee on the sacks or tags. Name some mixed and un- 

 mixed fertilizers used in your section. What is the commercial val- 

 uation of a fertilizer guaranteed 8 per cent, available phosphoric 

 acid, 3 per cent, nitrogen and 4.5 per cent potash? Require the 

 pupils to work several problems of the above nature, to familiarize 

 themselves thoroughly with this subject, 



