238 POTASH FERTILIZERS 



in both cases. Used in this way, however, they are low 

 grade fertilizers. Any treatment of them, however, makes 

 the resulting product rather expensive, and so far little is 

 being done to utilize these sources of potash. The German 

 potash salts can be produced under normal conditions too 

 cheaply to make other sources pay. 



183. Tobacco Waste. — In some sections of the countrv 

 the stems, stalks, and other waste from harvesting the crop 

 and manufacturing tobacco products, can be obtained 

 easily. If ground fine this waste makes excellent fertilizing 

 material, being fairly available. The potash content varies 

 from 4 to 10 per cent., phosphoric acid less than 1 per cent., 

 and nitrogen from 2 to 4 per cent., sometimes as much as 

 half of it in the nitrate form. 



184. Summary. — Although potassium occurs in soils to 

 a very considerable extent, it may be in a very unavailable 

 form. Moreover, some crops require considerable potas- 

 sium, and although it is usually returned to the farm in the 

 straw and other litter, its application as a fertilizer sometimes 

 pays. 



Practically the only source of potash in the world is the 

 mines at Stassfurt, Germany, where there are immense beds of 

 potash salts formed in past geologic ages by the evaporation 

 of sea water. The salts are chlorides and sulphates of potas- 

 sium, magnesium, and calcium with sodium chloride. 



Muriate of potash is made from carnallite (chlorides of 

 potassium and magnesium) and contains about 50 per cent, 

 potash. During the process there is obtained a so-called 

 potash manure salt containing 20 per cent, potash. Potas- 

 sium chloride is said to affect the burning qualities of tobacco 

 and to make potatoes watery. It has a tendency to make 

 soils acid, but applications of lime correct this effect and also 

 seem to overcome the bad effects of this fertilizer on crops. 



Sulphate of potash is made from potassium chloride and 

 magnesium sulphate, and contains about 50 per cent, 

 potash. An intermediate product called double potash 

 manure salt contains 27 per cent, potash. The sulphate has 

 no bad effects on plants and is not so apt to make soils 

 acid as is the muriate. 



