USE OF POTASH FERTILIZERS 185 



high-grade sulphate of potash and kainit. Ordinarily, 

 the price per pound of potash varies from 4 to 5 cents. 

 As in the case of nitrogen and phosphoric acid, the 

 market and field values as determined by crop yields 

 may be entirely at variance. Before potash salts are 

 .used, careful field tests should be made to determine 

 the actual condition of the soil as to its need of potash. 

 (See chapter X, Commercial Fertilizers.) 



244. Use of Potash Fertilizers. Wood ashes or 

 Stassfurt salts should not be used in excessive amounts. 

 Not more than 300 pounds per acre should be applied 

 unless the soil is known to be markedly deficient in 

 potash, and previous tests indicate that larger amounts 

 are safe and advisable. Potash fertilizers should be 

 evenly spread and not allowed to come in direct con- 

 tact with plant roots. They should be used early in 

 the spring before seeding or before the crop has made 

 much growth. Wood ashes make an excellent top 

 dressing for grass lands, particularly where it is de- 

 sired to encourage the growth of clover. There are 

 but few crops or soils that are not greatly benefited by 

 a light application of wood ashes, and none should 

 ever be allowed to leach or waste about a farm. 



245. Joint Use of Lime and Potash. When a pot- 

 ash fertilizer is used, a dressing of lime will frequently 

 be beneficial. The potash undergoes fixation, and when 

 it is liberated there should be some basic material as 

 lime to take its place. Goessmann observed that land 

 manured for several years with potassium chloride 

 finally produced sickly crops, but that an application 



