EXPERIMENT STATION BULLETINS. 301 



'^active insoluble^' nitrogen is less than the "inactive insoliihle" nitrogen 

 the total water-insohible nitrogen is not considered to he readily avail- 

 able and the plants may fail to derive any benefit from its use. 



Many of the fertilizer brands reported in this bulletin, especially those 

 having small percentages of nitrogen, show a large proportion of the 

 nitrogen to be in water-insoluble forms of questionable quality. 



THE POTASH SITUATION. 



All of the potash used by the fertilizer trade has, in the past, been sup- 

 plied by the immense potash mines of Germany. Owing to conditions, 

 incident to the war in Europe, the German Government placed an abso- 

 lute embargo on the exportation of potash in January, 1915, since which 

 time, none has been shipped into this country. In order to conserve the 

 supply then in the hands of the fertilizer manufacturers, all brands, con- 

 taining over three per cent potash, with the exception of a very few, 

 were withdrawn from sale during the past season. For the 1916 season 

 it will be necessary to reduce the amount offered in complete fertilizers 

 still further and it has been reported that no brands will be placed on 

 the market containing more than one per cent potash. 



The demand for potash in other industries has caused the price of the 

 unmixed potash salts to advance until they are now selling at ten to 

 twelve times the normal value. This is entirely out of proportion to 

 their agricultural value. 



The government, through the Department of Agriculture and Geolo- 

 gical Survey, has made extensive explorations for potash sources in this 

 country but up to the present the search has not been productive of re- 

 sults that promise any immediate relief. The investigations already 

 made, however, indicate that it may sometime be possible to produce 

 in this country sufficient potash to provide for our own needs. The most 

 promising sources are: the aluuite deposits in the mountains of Utah 

 and neighboring states; the feldspathic rocks of the eastern states; the 

 giant kelp of the Pacific coast and the mud of Searles Lake in California. 



THE PHOSPHATE SITUATION. 



Acid phosphate is the basis of all mixed fertilizers. This is made by 

 treating phosphate rock with sulfuric acid. The supply of phosphate 

 rock in this country is almost unlimited with large deposits in Tennes- 

 see, South Carolina, Florida and several of the western states. The 

 phosphoric acid in the rock is not readily available in its natural con- 

 dition but is made so by the treatment with sulfuric acid. In the usual 

 process of manufacture one ton of sulfuric acid is used for each ton of 

 phosphate rock. 



Owing to the greatly increased demand for sulfuric acid in the manu- 

 facture of war munitions, the price has risen from |5.00 to $6.00 per 

 ton to about |25.00 per ton. This necessarily increases the cost of man- 

 ufacturing acid phosphate and explains the rise in the price of this ma- 

 terial. 



