100 



Physics of the Soil. 



PARTS PER MILLION OF DRY SOIL 



ROUND NOT CULTIVATED 

 CLOVER AND OATS 



11 GROUND CULTIVAT 



CORN AND POTATOES 



NOT CULTIVATED 



CLOVER AND OAT-5 



CULTIVATED. 

 CORN AND POTATOES 



FIG. 32. Showing the difference between the amounts of nitrates and 

 of total soluble salts in the soil under cultivated and not cultivated 

 crops. 



