38 



Effective Farming 



structure. The expansion of water when freezing is very great, 

 and this force shatters clods of the soil, tending to promote 

 a granular structure. Repeated freezing and thawing further 

 break up the soil masses. A puddled soil is much benefited 



FIG. 15. The plow is an efficient agent for pulverizing the soil. 



by a good freezing. In fact when a soil is puddled in the grow- 

 ing season, it is often impossible to get it into good condition 

 until after a heavy freeze. 



19. Functions of water in soil. Water acts as a solvent 

 of plant-foods. These must be in solution to be absorbed by 



