8 AGRICULTURE FOR BEGINNERS 



of the soil enables the air to circulate through it freely, and 

 permits a breaking down of the complex compounds that 

 contain the elements necessary to plant growth.^ 



You have seen how the air helps to crumble the stone 

 and brick in old buildings. It does the same with soil if 

 permitted to circulate freely through it. The agent of the 

 air that chiefly performs this work is called carbonic acid 



FIG. 4. A BOUNTIFUL CROP BY TILLAGE ALONE 



jas, and this gas is one of the greatest helpers the farmer 

 has in carrying on his work. We must not forget that in 

 soil preparation the air is just as important as any of the 

 tools and implements used in cultivation. 



For most soils a two-horse plow is necessary to break 

 up and pulverize the land. 



If the soil is fertile and if deep plowing has always been 

 done, good crops will result, other conditions being favor- 

 able. If, however, the tillage is poor, scanty harvests will 

 always result. 



