92 FERTILITY AND FERTILIZER HINTS 



potash which is equivalent to 46 to 52 per cent, of potash. High 

 grade sulphate of potash containing 50 per cent, of potash is most- 

 ly used in America. 



Sulphate of potash is more expensive than muriate because 



Fig. 9. -Tobacco; a crop that is injured by excessive chlorides. — After 

 Conn. Exp. Station. 



the cost of manufacture is more, but it is desirable for tobacco, 

 potatoes, citrous fruits, and other crops that are injured by ex- 

 cessive chlorides.* 



5. Double Sulphate of Potash and Magnesia. — This product is 

 somewhat similar in action on crops to high grade sulphate of 

 potash. It contains considerable sulphate of magnesia which is 

 believed to exert a beneficial effect. It usually carries about 26 

 per cent, of potash. It is not used to any great extent in this 

 country, except by some fruit growers who prefer it to sulphate 

 of potash.* 



Potash Manure Salts. — There are other potash salts that vary 

 from 20 to 30 per cent, of potash called double manure salts and 



