POTASH FERTILIZERS 93 



potash manure salts which are not used extensively in fertilizers ; 

 although a potash manure salt containing 20 per cent, of potash 

 is sometimes sold which acts like kainit.* 



6. Potassium-magnesium Carbonate. — This is a dry, white manu- 

 factured product. It is not sold as extensively as kainit, sylvinit, 

 muriate of potash and sulphate of potash, but it is well liked by 

 tobacco growers. It is also used in Florida on oranges and pine- 

 apples. This product is an excellent source of potash for any 

 crops that chlorides prove injurious to. It usually contains from 

 20 to 25 per cent, of potash in the form of carbonate. On ac- 

 count of its dry nature, and because it does not absorb water from 

 the atmosphere, it is always easy to distribute.* 



Potash from Organic Sources. — Most of the potash used in 

 fertilizers is derived from the mineral sources but a small amount 

 is sometimes purchased in the form of wood ashes, tobacco stems, 

 cotton-seed hull ashes, and beet molasses. 



I. Wood Ashes. — Before the discovery of the Stassfurt de- 

 posits wood ashes were used more extensively than now and were 

 practically the chief source of potash to be found on the American 

 market. The potash in wood ashes is in a form (as carbonate) 

 which is very desirable for all plants. The product offered to the 

 trade is not uniform as different woods, parts of the same wood 

 as bark, twigs, etc., and methods of handling, all influence the 

 composition. The ashes from soft woods usually contain a lower 

 percentage of potash than the ashes from hard woods. Leached 

 wood ashes naturally carry much less potash than unleached 

 ashes. Ashes contain about 1.9 per cent, of phosphoric acid, 5.5 

 per cent, of potash and 34 per cent, of lime. They usually con- 

 tain more or less dirt and moisture which lower the composition. 

 The main source of wood ashes is Canada as not much wood is 

 burned in the United States.* 



Value of Wood Ashes. — From a chemical standpoint the value 

 of wood ashes is represented in the contents of potash, phosphoric 

 acid and lime. Ashes have another value in improving the con- 

 dition of the soil. They seem to help to conserve moisture, im- 

 prove the texture of soil and correct acidity, thereby increasing 



