28 



A study of the qualit}' of nitrogen which was used in the fer- 

 tiUzer formulas for 1915 shows that in the medium and high grade 

 goods 55.4 per cent and in the low grade goods 33.9 per cent of the 

 total nitrogen were from nitrate of soda and sulfate of ammonia 

 which are highly available. 



In regard to the organic portion of the nitrogen, a stud}- of the 

 table shows that the high and medium grade fertilizers carried 44.6 

 per cent and the low grade 06. 1 per cent of the total nitrogen in that 

 form. Thirty-seven cases were noted in the 1915 inspection where 

 organic ammoniates of low grade were used. Some cases among 

 this number may have resulted from the use of organic ammoniates 

 as a conditioner to improve the physical character of the goods. If 

 they were thus used attention should have been called to the fact 

 either on the bag or tag accompanying the fertilizer. In the 37 cases 

 noted, 19 were from low grade, 9 from medium and 9 from high grade 

 fertilizers. This is a somewhat larger number than was noted dur- 

 ing the season of 1914. It is believed that anyone studying the tables 

 of analyses will be able to readily detect cases where inferior forms of 

 organic nitrogen have been used. They should bear in mind three 

 distinct points in connection with the analytical data in making in- 

 terpretations. Those cases may be viewed with suspicion which show 

 collectively the following characteristics: 



(1). The inactive water insoluble organic nitrogen equal or ex- 

 ceeding the active water insoluble organic nitrogen. An exception iJ 

 this may he made in cases of tobacco fertilizers known to have most of 

 their organic nitrogen derived from cottonseed meal, co.stor pomace, or 

 other high grade organic vegetable compounds. 



(2). The total nitrogen found hut little in excess of the minimum 

 guarantee. 



(3). The presence of only small amounts of water soluble organic 

 nitrogen. 



Some interesting results have been secured by a vegetation ex- 

 periment, conducted at this station and presented elsewhere in this 

 bulletin, upon several brands of commercial fertilizer taken from the 

 season's inspection of 1914. These vegetation experiments, con- 

 ducted in pots, indicate that our laboratory method in most instances 

 gives full credit for the activity of the water insoluble nitrogen. 

 For details see pages 32 to 38 following. 



The following summary' table has been prepared to show the 

 average amount found and the quality of nitrogen used by each manu- 

 facturer in the brands sold in Massachusetts during 1915. 



