[lynde-dupré] on osmosis IN SOILS 117 



Does the subsoil become more efficient as a semi-permeable membrane 

 the longer the surface soil is cultivated? 



When rain falls on newly cultivated soil it washes some of the 

 finer particles into the subsoil. But we learned above that the finer 

 the particles of a soil the greater is its efficiency as a semi-permeable 

 membrane. The gradual washing of the finer particles of soil into 

 the subsoil should therefore increase its efficiency as a semi-permeable 

 membrane. 



Is moisture brought to the root hairs by osmotic -pressure? 



If the root hairs by taking water from the soil increase the con- 

 centration of the soil solutions near them, they increase the osmotic 

 pressure of these solutions. Thus water should move towards these 

 solutions by osmotic pressure from points at which the soil solutions 

 are less concentrated. 



