CAMBPELL'S SOIL CULTUE MANUAL 



113 



ble by air. It may as effectually seal the subsoil from 

 the air as does the coat of paraffine over the jar of jelly in 

 the pantry. 



A B 



Cut No. 11. Showing Heavy Rain Crust and how it is Broken up 



(a) Soil Mulch Restored by Cultivation, (b) Soil Mulch 



after Heavy Rain, Dissolved and settled down. 



When such conditions are found they must be destroyed. 

 The only thing is to promptly break up this crust and 

 put the soil into condition so there will again be a natural 

 mingling of the air and water with the particles of the soil. 

 This mingling must be in proper quantities of each that 

 is the soil must be of sufficient fineness and firmness below 

 the surface, or that portion properly termed the root bed, 

 so there may not be too much air, for while air is most 

 valuable in the soil in just the proper quantities, it is se- 

 riously detrimental in too large quantities. 



SHUTTING OUT THE AIR. 



In the experiment work we have conducted we have 

 noted some remarkable conditions and results. We have 

 found, for instance, that the air may be shut out by the 



