960 Popular Editions of Station Bulletins of the 



69 cents a pound, or more than three times its ordinary commercial 

 valuation. This same sheep manure was, also, with the exception 

 of wood ashes, the most expensive source of phosphoric acid or of 

 potash. If such prices are asked for this material, no intelligent 

 user of plant foods should give it a moment's consideration. 



For phosphoric acid, in readily available form, acid phosphate 

 is the cheapest source, and wood ashes the most expensive, the 

 phosphorus costing four times as much in the ashes as in dissolved 

 rock. The best grade of mixed goods approaches reasonably close 

 to the acid phosphate as an economical source of supply, the differ- 

 ence being less than half a cent a pound, but in complete fertilizers 

 of lower grade the cost per unit rapidly increases so that in low-grade 

 goods the phosphoric acid costs 20 per ct. more than in acid rock. 

 For somewhat slower-acting phosphoric acid, tankage and fish 

 scrap show good value. At the price quoted for the four samples 

 collected, $13 a ton, ground rock phosphate or floats is not considered 

 an economical source of phosphoric acid. At $8.50 a ton, at which 

 price it is known some goods have been sold, the insoluble phosphoric 

 acid would cost about 1.4 cents a pound. This is less than its 

 commercial valuation in mixed fertilizers. 



Potash, at the prices prevailing during the first half of 1914, could 

 be obtained cheapest in muriate, at an average price of 4.7 cents 

 a pound, in kainit it cost 5.4 cents, in high-grade mixed goods, 

 5.6 cents and in sulphate, 5.7 cents. In the lower grade mixed 

 fertilizers it cost 6.8 cents, or 44 per ct. more than in the muriate. 

 In wood ashes, however, the price broke the record for fictitious 

 valuation, reaching the limit of 30 cents a pound, or an increase of 

 almost 540 per ct. above what potash could be obtained for in its 

 cheapest form. The lime content of ashes has not been considered 

 in making these computations. Using the value of this element 

 would lower prices of phosphoric acid and potash somewhat. Of 

 course, the war has so changed the potash situation that these figures 

 are not applicable at present. 



The comparisons just given show that with the 



All mixed exception of a few materials, like sheep manure 



fertilizers and wood ashes, whose value has been greatly 



expensive, overestimated in popular opinion, the three elements 



of plant food most commonly considered can be 



obtained cheapest in comparatively simple chemicals or other 



natural compounds; that is, in unmixed form. For example, the 



average cost of nitrogen, in all the simple or natural sources of 



supply examined, except sheep manure, was 22 cents a pound, in 



complete fertilizers of high grade 24.2 cents, in those of low grade 



32.5, in those of all grades, averaged, 27 cents; and in the so-called 



bone and potash mixtures 33.5 cents. 



Similarly, phosphoric acid in unmixed goods, except floats, sheep 

 manure and ashes, could be secured at an average cost of 4§ cents 



