CHAPTER III 



Importance of Air in the Soil 



WATER, heat and oxygen are necessary for the 

 germination of seeds. Oxygen must come from the 

 air, hence it is necessary, in the preparation of the 

 seed bed, to leave the ground in condition for the cir- 

 culation of air. 



In view of the fact that seeds must germinate before 

 the plants can grow, the nearer the oxygen and moisture 

 are in the right proportion in the ground, the more 

 rapid will be the germination and growth of the plant. 



In the development of plant food for growing plants 

 the elements that go to make nitrates are largely con- 

 fined to the first few feet of surface soil. If the soil is 

 loose enough to allow access of air, nitrification is more 

 rapid, hence plant growth is more rapid. It obviously 

 follows then that plowing and cultivating are necessary 

 for the development of plant food. 



Air is also necessary to keep the ground in condition 

 for the retention of plant food after it has reached the 

 nitrate form. The roots of plants need oxygen in the 

 process of growing. Energy is required. The roots 

 penetrating through the ground absorb the oxygen and 

 thus acquire the needed energy for the work of pushing 

 the soil particles to one side. 



Nitrogen, in the form of nitric acid, is the most im- 

 portant of all plant food elements. Oxygen gives life 

 or activity to prevent destruction of nitrates after they 

 have once been made. Wet soils, rich in organic 



