THE SOIL 311 



son can be drained away by tiling, and evaporation 

 during a dry season can be prevented by shallow cultiva- 

 tion, thus forming a dust mulch. Deep cultivation during 

 a wet season will help to remove water by evaporation. 

 The farmer who learns how to keep the .proper amount 

 of moisture in his soil is the one who is successful in 

 growing large crops. 



APPARATUS TO TEST THE CAPACITY OP SOILS TO HOLD WATER 



During dry weather the water deep in the ground comes 

 toward the surface by moving from one particle of soil to 

 another, the same as it travels upward in a lump of sugar 

 or a cloth. Such a movement of water is called move- 

 ment by capillarity. This upward movement is often 

 necessary for seeds sown on the surface, so that they may 

 keep moist and grow. Capillarity is assisted by running a 

 roller over the ground, which crushes the clods and packs 

 the surface. This keeps the seeds moist, but the water 

 escapes by evaporation. Sometimes the soil is packed 

 just over the seed, when one or two rows are planted at 



