CAMPBELL'S SOIL CULTURE MANUAL 111 



CHAPTER XIV. 



IMPORTANCE OF AIR IN THE SOIL. 



Not as much importance has been given to a study of 

 the part played by air in the soil as the subject warrants. 

 Neither is it very well understood that its availability in 

 the soil is largely regulated by the mechanical arrange- 

 ment of the particles in the upper six or eight inches top 

 layer of the soil. 



Because we have seen it constantly demonstrated we 

 know the necessity of water in the soil for plant growth, 

 but it is not so easy to comprehend the material value to 

 the plant of air in the soil. We cannot see its effect in 

 anything like as broad a sense as we do the water, yet its 

 presence in proper quantities in the soil and about the roots 

 of the plants is just as vital to its life, health and growth 

 as water. 



Water without air and its component parts is worthless; 

 air without water and its component parts is equally 

 valueless to the growth and development of all farm 

 crops. 



Consider the subject carefully. How many times have 

 we seen a field of wheat, corn or oats, possibly half-grown, 

 and noted that in some depression the crop was ranker in 

 growth and also a darker green. If a rain of considerable 

 magnitude comes, and the depression fills with water 

 and remains there for several days, the plants that seemed 

 to have the advantage before the rain now begin to lose 

 their dark, healthy green color; if the water remains long 



