SOURCES OF PLANT-FOOD 



to the quality of the potato, and on light soil the 

 muriate may always be used. 



Sulphate of Potash. Some sulphate of potash 

 is imported into this country. Its content of 

 potash may vary 1 or 2 per cent below or above 

 50. Its physical condition favors mixing more 

 than does the muriate. It usually costs several 

 dollars a ton more than the muriate, and the fact 

 that it is known to favor quality in tobacco, and 

 is popularly supposed to do so in the potato, 

 creates demand at the higher price. It is soluble 

 in water, and quickly available. As a rule, it has 

 no higher agricultural value than the muriate. 



Kainit. Unlike muriate and sulphate of pot- 

 ash, kainit is a crude product of the German mines, 

 having received no treatment to remove impuri- 

 ties. It contains 12 to 13 per cent of potash, and 

 is rated as a sulphate, but one third of it is com- 

 mon salt, and in effect upon quality it should be 

 classed with muriate and not sulphate. Its low 

 content of plant-food should confine its use to 

 regions relatively near the seaboard. When 

 shipped far inland, the price becomes too high to 

 give a reasonably cheap pound of potash. 



Wood-ashes. Wood-ashes contain lime and 

 potash, with a small percentage of phosphoric 



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