128 MAINi: AGRICULTURAL EXPERIMENT STATION. I912. 



and report at a similar meeting in March 1911. As a result of 

 this investigation the alkaline permanganate method, somewhat 

 modified, was adopted to be used by the several states repre- 

 sented in determining the grade of organic nitrogen in ferti- 

 lizers inspected. 



The alkaline permanganate method adopted is open to some 

 criticism. It is assumed in this method that all organic nitro- 

 gen soluble in water is available or active. This assumption 

 is probably generally correct, but may not be always, as it has 

 been found that some soluble forms of leather treated with 

 alkali are not more available than the raw material. Again 

 in the case of a high grade fertilizer such as is generally used 

 in the potato growing region of this State, often not more than 

 0.3 per cent of water insoluble nitrogen is found to be present. 

 In order to follow the method exactly it is sometimes necessary 

 to take 16 or more grams of the material, an impracticable 

 amount with which to work. In using such large amounts, 

 more than 15 grams, so much organic matter other than the 

 nitrogen is introduced that the permanganate is very quickly 

 used up and too low results may be ohtained. For this reason 

 in this laboratory whenever the amount of insoluble nitrogen 

 in the fertilizer was so small that more than 15 grams would 

 need to be taken to follow the method, the determinations 

 have not been made. 



Not enough vegetation tests in comparison with the labora- 

 tory methods have been made to warrant drawing too close an 

 application of the results to mixed goods. It is not claimed that 

 it will show absolute agricultural value but vegetation tests 

 carried on at the Rhode Island Experiment Station on materials 

 subjected to both tests indicate a quite close agreement. It is, 

 however, far better than no method and in a general way makes 

 it possible to compare the availability of the nitrogen from 

 different sources and in different brands of mixed fertilizers. 

 Its adoption by the States named is a distinct progress in fer- 

 tilizer control work. As time goes on the method will be 

 checked up with more vegetative tests and it will doubtless be 

 possible to more correctly apply the results obtained in the lab- 

 oratory as a check upon the results that may be expected in the 

 field. 



