COMMERCIAL FERTILIZERS IOI 



in pure water and cannot be used immediately by the roots, 

 nevertheless it has some value as fertilizer for some soils 

 and crops. When ra\v phosphate is kept for some time 

 in contact with decaying vegetable matter or mixed with 

 manure, a part of its phosphate changes into a form which 

 roots can use. 



Fertilizers containing potash. The commonest of these 

 is kainit. It is dug from deep mines in Germany. It 

 contains about twelve per cent of potash. Muriate of pot- 

 ash is obtained from the same source. About half its 

 weight, or fifty per cent, is potash. Kainit and muriate of 

 potash are nearly white, resembling somewhat coarse 

 table salt. 



EXERCISE. Try to get samples of as many as possible of the fer- 

 tilizers mentioned above for the teacher to show during class. In your 

 notebook describe them. Be ready to report the effects of any fertilizer 

 test you may know about. 



NOTE TO THE TEACHER. If possible, exhibit small samples of any 

 of the fertilizers mentioned in the lesson. Which ones dissolve quickly > 

 Which ones get lumpy? Exhibition of ordinary mixed or manufactured 

 fertilizers will be of doubtful profit to the class, and may involve per- 

 sonal interests. 



FIG. 65. A WINDOW PLANT WELL TREATED 

 AS TO LIGHT AND FOOD 



