1912.] PUBLIC DOCmiENT — No. 31. 61 



and New Jersey co-operated in an effort to make a careful study 

 of the Jones' modification of the " Alkaline permanganate 

 method " and Street's '' JSTeutral permanganate method " for 

 testing the activity of the water insoluble organic nitrogen in 

 mixed fertilizers. Satisfactory results were obtained with the 

 Jones' modification, which were confirmed on the same samples 

 by means of vegetation experiments conducted at the Rhode 

 Island Experiment Station. The work proved so satisfactory 

 that in March, 1911, the Jones' modification was adopted pro- 

 visionally by the jSTew England, 'New York and Xew Jersey ex- 

 periment stations. 



All of the complete fertilizers reported in this bulletin have, 

 therefore, been tested as to their organic nitrogen activity. Out 

 of a total of 334 brands analyzed, 43 or nearly 13 per cent, of 

 the whole number, have sho^^^l an activity of their water insol- 

 uble organic nitrogen of less than 50 per cent. 



So far as one is able to judge from the analytical data and 

 the explanations furnished, the following facts may be de- 

 duced : — 



1. Some manufacturers used nitrogen-containing material of 

 a low availability. 



2. In some cases it was used as a direct source of nitrogen to 

 bring the material up to its minimum guarantee. In other cases 

 it was used to raise the guarantee above the minimum. In still 

 other cases it was employed as a filler or to improve the mechan- 

 ical condition of the fertilizer. 



3. It is possible that the inactive materials employed were 

 not sufficiently treated to render their nitrogen available. 



It is hoped that manufacturers will endeavor to improve con- 

 ditions another season, for it is believed that the consumer of 

 commercial fertilizers — at least of the better grades — is enti- 

 tled to receive all of his nitrogen in such an available form as is 

 called for by the 50 per cent, alkaline permanganate standard. 



(2) Phosphoric Acid. — Many of the fertilizer mixtures 

 contained large overruns in total phosphoric acid, while the 

 available phosphoric acid on the same brands has shown a con- 

 siderable shortage. This may have been due to incomplete 

 acidulation of the bone or raw mineral phosphate used, or to 

 the addition of considerable unacidulated rock phosphate, bone 



