Manc/iester Memoirs, Vol. Iviii. (1914), No. 6. 



VI. How does the Plant obtain its nutriment 

 from the soil ? 



By A. D. Hall, M.A., F.R.S. 



[.special ici-tiire, A/arch 4ih, igij. ) 

 (Received for publication Jamtary i2ili, igi4.) 



The theory of the nutrition of the plant may be said 

 to begin with the discovery that the plant draws but a 

 small portion of its substance from the soil, though from 

 that source alone it derives certain elements — in particu- 

 lar nitrogen, phosphorus, and potassium — without which 

 growth will not take place. Moreover, it was early shown 

 that the compounds thus supplied by the soil must be in 

 a state of solution before they can reach the plant, so 

 that the source of nutriment is that body of water which 

 clings by surface tension to the particles of the soil — a 

 body which, though subject to considerable fluctuations 

 through its irregular depletion and renewal, is a perma- 

 nent element in the soil. This water contains, amongst 

 other materials, nitrates, phosphoric acid and potash 

 salts, derived from the solid materials of the soil ; it serves 

 as the intermediar}' whereby they are passed on to the 

 plant and is conveniently described as the soil solution. 



Early in the history of agricultural science it was 

 realised that the soil itself contains a considerable stock 

 of the essential nutrients — nitrogen, phosphoric acid and 

 potash, so that it was difficult to understand why the 

 ordinary crop should ever be so short of these substances 

 that any further supply in the form of a fertiliser could 



Alay 2jfh, igi4. 



