142 



FOOD 



the ground is made rough and porous much more water 

 will be absorbed than if the ground has been left smooth 

 and hard. The loosening of soil so that it may catch the 

 rain and prevent the run-off is called tilling. 



The first tilling, in preparing the soil for the seeds, 

 exposes the under layers to the action of the air and also 

 helps to bring more plant-food to the surface. Another 

 necessity for tilling is to put the soil into such a porous 

 and softened condition that the tender roots of the tiny 

 plants may work their way into it. Porous soil also 

 allows more air to enter it. 



All tillage of the soil, after the seeds have been 

 planted, is to kill weeds and to save the moisture which 

 is in the soil. We have learned that water moves 



through the soil by capillar- 

 ity and if we want to stop 

 the movement we must close 

 the holes. If you place 

 some powdered sugar upon 

 a cube of sugar, as shown in 

 the illustration, and then 

 touch the cube to some 

 colored water (red ink) you 

 will see the water rush up 

 the cube but stop when it 

 reaches the powdered sugar. 

 Capillarity is good in the 

 cube sugar but very poor in the powdered sugar. Try 

 the experiment. We can do the same thing to soil'by 

 loosening the top of the soil and making it fluffy and 



Cut supplied by the International Harvester Co. 



