30 



Eighty-four and seven-tenths per cent of the total 



Character of phosphoric acid found in all the complete fertilizers 



Phosphoric analyzed was present in available form, and 52 per 



Acid. cent of the available phosphoric acid was present in 



water soluble fonn. The phosphoric acid in mixed 

 commercial fertilizers will usually be found derived from various 

 sources. Ordinarily most of the available phosphoric acid will be 

 derived from some grade of superphosphate or acid phosphate. The 

 presence of bone or tankage will furnish considerable phosphoric 

 acid, which, unless acidulated, will show a large amount of this ele- 

 ment insoluble, not being dissolved either by water or neutral citrate 

 of ammonia in our laboratory operations. An examination of the 

 superphosphates or acid phosphates showed 9.'5 per cent of the average 

 total phosphoric acid as available, and 71 per cent of the available 

 phosphoric acid was found present in water soluble form. This 

 shows about the usual phosphoric acid availability of this class of 

 materials. 



The content of potash found in the average com- 



Character of mercial mixed fertilizer during the year was between 



Potash. 3 and 4 per cent. The potash was reduced to this 



small amount on account of its scarcity, due to the 

 European war. Only one of the larger fertilizer companies (The 

 Mapes Formula & Peruvian Guano Company) maintained their full 

 quota as in previous years. There has been no indication that the 

 scarcity of potash salts has resulted in the use of inferior forms, such 

 as feldspar or granite, in mixed fertilizers. It is reported that some 

 of the larger companies have recently perfected a process which ren- 

 ders considerable of the potash in this class of material soluble in 

 water. Potash thus made soluble should prove an efficient source 

 of this element of plant food. In the tables of analysis, wherever 

 potash has been found present in form of sulfate or carbonate, an 

 asterisk (*) or dagger (f) has been used in the "found" potash column. 

 Footnotes will be found giving the proportion of each form of potash 

 present. "Wherever no character is given it may be understood that 

 potash was found present as chloride. The form of potash used in 

 tobacco goods should exclude chlorides as far as possible. 



The total water soluble potash present in the 34 brands of to- 

 bacco fertilizer analyzed was 3.95 per cent, of which 2.97 percent 

 was from sulfate and 1.02 percent from muriate. Three brands 

 were analyzed, having their potash guaranteed as carbonate. In 

 these brands, out of a total of 5.45 per cent water soluble potash, 

 2.73 per cent was as claimed, .76 per cent was present as muriate and 

 1 .90 per cent as sulfate. It is believed that with few exceptions the 

 potash was actually present in the fonn guaranteed. It is possible 

 that the small amount of chlorine and sulfates present where only 

 carbonate of potash was guaranteed may have been derived from 

 some other component of the fertilizer. 



