56 AGRICULTURE FOR COMMON SCHOOLS 



quickly in the soil, and yields its nitrogen for the use of 

 plants. 2. Tankage also comes from the slaughtering houses 

 in large cities. It is made from the intestines and their con- 

 tents, small bones, waste flesh, and other parts of the slaugh- 



II. RESULT OF USING FERTILIZERS ON WHEAT 



KPN stands for potash, phosphorus, and nitrogen. O stands for no fertilizer. 

 KN stands for potash and nitrogen. Notice which element was most helpful in 

 these cases. j^y courtesy of the Indiana Experiment Station 



tered animal that cannot be used otherwise. This material 

 is heated by steam and, when dry, ground into meal. Tankage 

 usually contains some phosphoric acid as well as nitrogen. 

 There are two principal kinds of tankage: (1) Concentrated 

 tankage, containing 10 to 12 per cent, of nitrogen and very 



