Lecture 5 



121 — 



Artificial Media 



and anions present in the soil solution must neces- 

 sarily be accompanied by equivalent quantities of 



Root 



y , " 



In soil solution 



H 



H + Ca(HC03)2 +(m- DiUiCOz) 



Ca ' : — • — : ' 



In soil solution 



padfcie 



Uav 

 partide 



^Root 



Contact intah 



Jioof 



Contact deptetion 



Textfigure 34. — Top: soil solution mechanism 

 in utiliza,tion of absorbed ions. Middle: contact 

 exchange of ions in overlapping oscillation volume 

 of clay particles. Bottom : exchange of ions between 

 root and c^ay particles. (From Jenny and Over- 

 street, 1939). 



cations. Further consideration of this general point 

 will be given in a discussion of problems of potassium 

 nutrition. 



