96 THE PRINCIPLES OF AGRICULTQRE 



cause plants can better do without it, but 

 because it is usually more abundant in soils. 

 Potash has an important office in the produc- 

 tion of firm, woody tissue and of starch, and 

 it is thought to be particularly needed by fruit- 

 plants, potatoes, and root crops. It is gen- 

 erally deficient in sandy and peaty soils. 



147. Like phosphoric acid, potash becomes 

 available with a liberal supply of humus and 

 by good tillage ; and the potash in barn ma- 

 nures is soluble and valuable. Whenever wood 

 ashes can be cheaply obtained they form a valu- 

 able source of potash, for the potash taken 

 from the soil by the trees remains in the ashes 

 when the wood is burned. 



148. Potash is found in great deposits in 

 Germany, very much as common salt is found 

 in the United States. There it is mined and 

 sold. It can be bought in the form known as 

 the muriate of potash, or more properly potas- 

 sium chlorid, KC1. Another form of potash is 

 the sulfate, K 2 S04. The sulfate costs a little 

 more than the other, because it is made from 

 the muriate. For general purposes, the muri- 

 ate is recommended over the sulfate because 

 it is cheaper ; but the muriate has a dele- 

 terious effect on tobacco, and it is thought 

 to give less satisfactory results on sugar-cane 

 and potatoes. 



