194 SOILS AND FERTILIZERS 



242. Commercial Value of Potash. — The market 

 value of potash is determined from the selling price of 

 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 both nitrogen and phosphoric acid, 

 the market and the field values may be entirely at 

 variance. Before potash salts are used, careful field 

 tests should be made to determine the actual condi- 

 tion of the soil as to its needs in potash. 



243. 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 de- 

 ficient, and previous tests indicate that larger amounts 

 are safe and advisable. Potash fertilizers should be 

 evenly spread and not allowed to come in contact with 

 plant tissue. 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 desired to en- 

 courage 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. 



When a potash 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 



