26 LIFE ON THE FARM. 



of nitrogen and oxygen about seventy-five per 

 cent of nitrogen and twenty-five per cent of oxy- 

 gen. It also contains small amounts of other ele- 

 ments and compounds which will not be spoken of 

 here. Air is just as essential to soil as water is; 

 and, although it cannot be seen entering and leav- 

 ing, yet the soil breathes just as truly as plants and 

 animals do. That soil does contain air may be 

 found by filling any tall vessel with dry earth and 

 pouring water on it. Bubbles will be seen to 

 escape as the water sinks. The air which filled 

 the spaces between the earth particles was replaced 

 by the heavier water and escaped as bubbles at the 

 surface. 



The roots of most plants require air just as their 

 leaves do; and if in any way they are deprived of 

 the supply, the entire plant will die. When a field, 

 with germinating seeds or a growing crop, is 

 flooded for several days, great injury or total 

 destruction will result. This is due to the water's 

 shutting out the supply of air which is so essential 

 to germinating seeds and growing roots. Seeds 

 contain compounds of such a nature that oxygen 

 is needed for their transformation before they can 

 be used by the growing sprouts, and the air has to 

 supply this needed element. 



WHY CULTIVATION IS BENEFICIAL. 



The rapidity of germination and growth depends 

 to a large extent upon the quantity of air supplied 



