38 Fertilizers 



It is important not because the supply is large and the 

 price low, but because it is one of the most concentrated, 

 one of the richest in nitrogen of the organic nitrogenous 

 fertilizing materials. It is one of the best, since its physi- 

 cal character is such as to permit of its very rapid decay 

 in the soil during the growing season. This tendency to 

 decay rapidly is plainly apparent, when it is remembered 

 that blood as it exists in the animal is in fluid form, and 

 naturally any material which is sufficiently finely divided 

 to permit of its ready flow, and is not associated with any 

 hard or fibrous material, possesses characteristics which 

 enable a rapid breaking down when subjected to the 

 proper temperature and moisture conditions which 

 promote decay. 



Dried blood for fertilizing purposes is chiefly obtained 

 from the large slaughtering establishments. The markets 

 recognize two distinct kinds, red and black. The former 

 is carefully dried with hot water and contains 13 to 14 

 per cent of nitrogen. It is uniform in composition and 

 because of its quality commands the higher price. It 

 contains only traces of phosphoric acid. The market prod- 

 uct is standardized and guaranteed to contain 16 per 

 cent ammonia. The latter black blood is dried at a 

 higher temperature with less care, which gives it a darker 

 color and leathery character. It also contains consider- 

 able impurities, such as bone. It contains from 6 to 10 

 per cent of nitrogen and often as high as 4 per cent of 

 phosphoric acid. In this case, also, the market product 

 is standardized and guaranteed to contain 12 per cent of 

 ammonia. 



The red blood is considered a high-grade fertilizer 

 material, uniform in composition, high in nitrogen and 

 of excellent mechanical texture. The black blood, while 



