CAMPBELL'S SOIL CULTURE MANUAL 



115 



pletely destroying the crust. On the morning of the fourth 

 day there was a perceptible difference in the color of the 

 leaves in this half of the orchard. In seven days the 

 trees in the disked portion had resumed their healthy 

 dark green color, while the undisked portion had become 

 still lighter in color. The balance of the orchard was 

 then disked. Although the extreme weather continued 



Cut No. 12. Showing Effect of Shutting Air from Roots 



four weeks longer, the leaves of the whole orchard resumed 

 their fine, deep green, and new growth was apparently 

 rapid. 



Similar conditions have since been noted in wheat. 



