IMPORTANCE OF AIR IN SOIL 29 



moisture. Consequently, if all the air were removed 

 from the ground there would be no forming of nitrates, 

 and plant food could not be produced. Too much air 

 makes cracks and fissures in the soil, drawing out 

 moisture, oftentimes to such a depth as not only to 

 stunt the crop, but kill it. Too much air in the soil in 

 the spring can easily cause the loss of enough moisture 

 to grow a crop. 



It is a well known fact that the atmospheric pressure 

 on the earth's surface is 14.7 pounds per square inch at 

 sea level. The amount of nitrogen in these 14.7 pounds 

 of pressure is 77%. It is perfectly logical, if the 

 ground is broken up and thoroughly pulverized when 

 plowing, that this pressure of 14.7 pounds per square 

 inch will force the air into the soil taking with it 77% of 

 free nitrogen. It is the air circulating around every 

 particle of soil in conjunction with capillary moisture 

 that liberates plant food for the growing plants. 



This field is similar to that shown on page twenty-eight but in a much 

 less aggravated form. However, if left to itself for any length of time it 

 is easily possible to see how the cracks would widen and deepen. 



