22 



THE PRINCIPLES OF ZOIL MANAGEMENT 



The second direct chemical action of water, and 

 perhaps the most important of all the chemical changes 

 involved in soil formation, is that of solution. It is 

 worth while to remember that no mineral is completely 



Fis. 9. Traces of residual soil in a limestone quarry. Note the joints and 

 partings. Soil of a dark red. silty character 



insoluble. They differ greatly in solubility, ranging from 

 the readily soluble common salt to the exceedingly 

 insoluble silica or quartz. But all are amenable to the 

 action of pure water. In the above instance of hydration 

 of feldspar, we have a type of a large number of changes 

 in minerals which alter their solubility. And by altering 

 the solubility of one mineral the other minerals present 



