80 AMERICAN MANURES. 



more than half its weight of alkaline bases 

 potash and soda. Among the cultivated potash 

 plants, are indian corn, beets, turnips arid pota- 

 toes. 



II. Lime Plants the bulk of the ash of which 

 is composed of the salts of lime and magnesia. 

 Among these are beans, peas, clover and to- 

 bacco. 



III. Silica Plants those in which silica pre- 

 dominates. Among these are wheat, rye, oats 

 and barley. 



This is only a general classification. The 

 farmer should know the actual amount of each 

 of the elements of fertility required by an aver- 

 age crop of any kind of plant he cultivates. A 

 field properly prepared for culture ought to con- 

 tain a sufficient quantity of all the inorganic 

 materials required for the intended crop, and in 

 a form adapted for assimilation by the plant ; 

 together with a certain amount of ammoniacal 

 salts or nitrates and decaying vegetable matter. 

 For instance, if it is the intention of the farmer 

 to raise potatoes, he should know that both lime 

 and potash are required, and what quantity of 

 each ; for the potatoe belongs to the lime plants, 

 as regards its leaves, and the potasji plant as 

 regards its tubers. In raising beets, phosphate 

 of magnesia is required, and only a small quan- 

 tity of lime ; but in growing turnips much phos- 



