PLANT-FOOD AND AGRICULTURE. 229 



value of 2.8 pounds of potash and .9 pounds of phosphoric acid. 

 If these ashes are worth bO cents a bushel, and we consider the 

 phosphoric acid worth 6 cents a pound, the- potash in our ashes 

 stands us at about 8| cents a pound. If h^ached ashes are used, 

 at 10 cents a bushel, the potash supply is costing about 20 cents 

 a pound. Cai'bonate of potash is, however, a good form in which 

 to use potash, as the carbonic acid has an action of itself in the 

 soil, in aiding the solution of plant-food. 



Of late years, however, the principal agricultural supply of 

 potash is looked for in Kainite or German potash suits. These are 

 the product of the salt mines of Germany, and are put on the mar- 

 ket in the form of sulphate of potash and muriate of potash of 

 varying strength. The most economical for the farmer are the 

 high grades. The sulphate of potash which contains 78-80 per 

 cent, of the pure salt, furnishes about 43 per cent, of actual pot- 

 ash, and when the commercial salt is quoted at 4 cents a pound, 

 the actual potash therefrom is costing about 9 1-3 cents a pound. 

 Muriate of potash, the other potash salt of these mines, when of 

 80 to 85 per cent, muriate, contains about 50 pounds of actual 

 potash, and furnishes, when the commercial article is selling at 8 

 cents a pound, the potash at about 6 cents a pound. We thus find 

 that the cheapest supply of potash is in the high grade muriate. 

 To furnish the potash at the price it is procured for in the muriate, 

 we should buy the sulphate of the same grade at about 2| cents a 

 pound, and wood ashes at about ]'! cents a bushel. 



These salts of potash are supposed to act differently on crops, 

 but we do not consider the matter at all proved at present. Indeed, 

 at present prices, we prefer to apply the muriate in nearly every 

 case, or, better still, two-thirds muriate and one-third sulphate. 

 This for reasons that we shall not attempt here to offer. 



When we apply our potash compounds to the land, they become 

 dissolved by the rains, and wash into the soil. They are then 

 decomposed into their constituent parts, separating into sulphuric 

 or muriatic or carbonic acid, and potash, and while the acids are 

 not retained at all closely by the soil, but follow the water of drain- 

 age until they meet new compounds, and are subject to different 

 actions, the potash is quite strongly retained. It is, hence, easier 

 to saturate our soil with potash than with phosphoric acid, and if 

 our soil is deficient in this element, we can hope to more speedily 

 cause it to be diffused through the soil, and thus become more 

 accessible to the crops. In applying potash, then, we desire to 



