PRINCIPLES OF MANURING. 55 



Potash manures come largel}- from Germany in the shape of 

 potash salts. We have also potash that is extracted from ashes, 

 but is not used in this form as a fertilizer. The German potash salts 

 ax'e mined, and exist at first associated with other minerals. They 

 are purified and sent to this country in quite large quantities. The 

 substances found associated with them are common salt, and the 

 sulphate and chloride of magnesia. These compounds are not 

 always sufficiently removed from the imported potash manures, and 

 while the common salt and sulphate of magnesia do no liarm, 

 chloride of magnesia in an}- considerable quantity- is actuall}- poison- 

 ous to plants. 



For this reason it is well to apply potash salts, especiallj' the 

 chloride, to the land, some little time before the seed is put into the 

 soil, so that the poisonous compounds, if present, can become suffi- 

 ciently diffused to prevent harmful results. The sulphate of potash 

 is the safer manure to use, but is more costly than the chloride, 

 (mui'iate) . 



Unleached ashes contain quite a percentage of potash, which varies 

 much according to the wood from which the ashes come, and the 

 manner of burning. The potash in wood ashes is in a valuable form, 

 (the carbonate) and ordinarily can be bought as cheaply as when 

 purchased in any other form, if we take into account the phosphoric 

 acid and lime which the ashes contain besides. 



Good hard wood ashes from wood burned in fire-places or cooking 

 stoves, are well worth twenty-five cents a bushel to any farmer, if 

 he finds that his farm needs potash. The question is often asked, 

 what is the difference between leached and unleached ashes, and 

 which is the cheaper at ordinary prices ? The chief difference is 

 that the former contains much more potash than the latter. The 

 process of leaching takes out very little but potash. 



Now as to which kind a farmer had better buy, depends upon what 

 he wants of the ashes. If his land needs potash manures, then he 

 had better buy the unleached ; but if he wishes to use the ashes 

 simply as a means of liming his land, then the leached will serve his 

 purpose just as well and be much cheaper. The manner in which 

 a farmer is to learn whether he needs potash, lime, or any other 

 ingredient applied to his fields, we will consider later. 



