116 CAMPBELL'S SOIL CULTURE MANUAL 



oats and corn, with same results from similar treatment, 

 all pointing to the fact that both the growth and yield 

 of crops may be very materially diminished by shutting 

 the air from the roots of the plants. 



To illustrate more fully the effect of shutting the air 

 from the roots we take the accompanying cut No. 12 from 

 Goff's book, "Principles of Plant Culture." 



To make this test practical, two glasses were filled 

 about half full of soft water, then two slips of the same 

 kind of a plant as near alike as could be selected were placed 

 in the two glasses and then a thin layer of olive oil was put 

 upon the water in one glass to prevent the air reaching 

 the water, the glasses placed in a warm light place; in a 

 very few days live healthy roots are seen developing from 

 the slip in the glass without the oil, while the oil covered 

 glass not only shows no roots but the leaves soon begin to 

 wither. While it must be remembered that slips from 

 any and all trees or shrubs will not do this, only such as 

 willow, nasturtion, or wandering jew, etc. Yet it demon- 

 strates clearly and beyond a shade of doubt that the air 

 plays a very important part in the growth and develop- 

 ment of roots and plants. 



One more thought before closing this very important 

 topic. The full and complete knowledge of the relation 

 of air and its utility in the production of all farm crops 

 means the absolute certainty of the greatly increased 

 yields of your fields without any material increase in the 

 cost of production, because it is found in utilizing what 

 is actually going to waste, not by a specially increased 

 amount of labor, but through doing the work commonly 

 done with an eye to bringing about that certain necessary 

 physical condition more through a little different manner 

 of tilling the soil when it is in proper condition to work. 



