VIII.] 



POTASH 



255 



differences between the potash added in the manure 

 and removed in the crops: 



On the whole, about one-half of the estimated surplus 

 of potash received by the manured plots still remains in 

 the top 9 inches of soil. 



Dyer further estimated the proportions of potash in 

 the same soils which was soluble in a I per cent, solu- 

 tion of citric acid, and found that both the surface and 

 the subsoil down to a depth of 27 inches contained more 

 of this readily soluble potash where it had been applied 

 as manure, than did the companion plot receiving no 

 potash, as will be seen from the following table : 



These determinations show that soluble potash salts 

 applied to the land are retained chiefly by the surface 

 soil, as much as one-half of the estimated additions of 



