tion are not so fully understood as they should 

 be. A better understanding of these prin- 

 ciples will make the operation more effective, 

 because it will be more thorough. 



The offices of tillage are several. Among 

 the most important ones are: 



1. The setting free of plant food, by in- 

 creasing the chemical activities of the soil. 



2. The soil is made finer, and hence pre- 

 sents greater surfaces to the roots, thus in- 

 creasing the area from which the roots can ab- 

 sorb nutriment. 



3. The surface of the soil is kept in such 

 condition that it immediately absorbs all the 

 rain that falls during the summer, when it is 

 apt to be dry. Little is lost by surface drain- 

 age. 



4. Moisture is conserved thereby. Where 

 the surface remains undisturbed for weeks, 

 the soil becomes packed, so that the moisture 

 from below readily passes to the surface and 

 is evaporated, thus being lost to the growing 

 crop. If the surface is kept light and loose 



154 



