Sub-Irrigation 



condition, and for this reason may be better able to resist and overcome 

 the attacks of certain classes of insects. As a rule, plants are less affected 

 by stem-rot upon sub-irrigation benches than upon surface-watered ones, 

 but this cannot be stated as absolute. 



In practice, it has been found that the soil upon the sub-irrigation bench 



Sub-Irrigation Tile 

 Showing Carnation roots growing around and attached to bottom ot tile 



is maintained in a more open, friable condition than upon the surface- 

 watered bench. This is readily understood, because the water evaporating 

 and passing upward through the soil has a tendency to lift or lighten the 

 soil; whereas in the surface-watered bench, the water, being poured upon 



174 



