44 CONTROL SERIES No. 45 



Conclusions Drawn from the Experiment. 



Dark Dried Blood. Both the nitrogen activity by the laboratory methods 

 and the nitrogen availability by the vegetation test show the quahty of the nitrogen 

 in this product to compare favorably with that in dried red blood; indicating that 

 the dark color, which is quite likely due largely to the method of drying, is no 

 indication of inferiority in quality. 



Foreign Nitrogenous Tankage. This is the first year's experiment with 

 this product. Results of both laboratory tests and vegetation experiment 

 indicate that the water insoluble nitrogen, which comprised over 69 per cent of 

 the total nitrogen which it carried, was about 20 per cent less available than was 

 the water insoluble nitrogen from the high grade animal and vegetable ammoni- 

 ates. 



Hoof Meal. This year's results confirm the results with this product for the 

 past two years, and class the nitrogen as of good quaUty, being almost equal to 

 dried blood. 



Peruvian Guano. The fact that the water insoluble nitrogen in this product 

 was condemned by the alkaline method is quite likely due to the natm^al presence 

 of uric acid in the guano. For some reason uric acid tests very low by this 

 method. The vegetation test shows the quality of the nitrogen in Peruvian 

 guano to be above that in dried blood. 



Milorganite. The results of both this and last year's experiment indicate 

 that this material is a fairly satisfactory soxu-ce of organic nitrogen, although 

 not quite equal to many of the high grade animal and vegetable ammoniates. 



Imported Process Tankage. About 74 per cent of the total nitrogen in 

 this material was found to be in water insoluble form. As measured by the 

 vegetation test it is about 22 per cent less available than the insoluble nitrogen 

 from the better grades of animal tankage and fish. This was the first year's 

 test on this product. 



Rehmsdorf Tankage. This is the fourth year that this material has been 

 under experiment at this institution. The first three years the water insoluble 

 nitrogen showed an availability of less than 50 by the vegetation test, which 

 would class it of inferior quality. This year's results indicate an improvement 

 in the quaUty of the insoluble nitrogen (about 69 per cent of the total nitrogen 

 was in water insoluble form), although it is still about 20 per cent less available 

 than that from the better grades of animal tankage. 



Process Tankage. About 90 per cent of the total nitrogen was in water 

 insoluble form. This completes two years' experiment with this product and 

 both years have shown the insoluble nitrogen to be of passing quality, with a some- 

 what better showing this season than in 1927. It is, however, still about 20 

 per cent less available than that from bona fide animal tankage and fish. 



Darling's Tankage. About 64 per cent of the total nitrogen was in forms 

 insoluble in water. The availability of the insoluble nitrogen was quite satis- 

 factory, although about 11 per cent below that for fish and the better grades of 

 animal tankage. 



Hynite Tankage. This is the third year that this product has been under 

 experiment. About SO per cent of the total nitrogen was in water insoluble 

 form. It showed quite a satisfactory avaOabihty this season, being only about 

 10 per cent lower than that of animal tankage and fish. This shows a gratifying 

 improvement over the two previous years, when the availability of this part of 

 the nitrogen was considerably under the passing mark of 50 per cent. 



