HOW THE ROOT GETS FOOD FROM THE SOIL 17 



tumbler quite dry, put a little water in the second, 

 still more in the third, and so on, increasing the amount 

 of water so that the earth in the last tumbler will be 

 very wet. By looking at the earth in the tumbler in 

 which the wheat grows best and rubbing it between 

 the fingers you can get a fair idea of the appearance 

 of soil which contains the right amount of water. 



Third, we must give the roots air by breaking up the 

 crust on the surface of the soil. The crust keeps out 

 air and helps water to escape from the soil. If it is 

 broken up, it makes a dry mulch which lets the air into 

 the soil but keeps the water from escaping. 



"Water your garden with a rake "N simply means, 

 break up the crust and keep the water from escaping 

 from the soil into the air. This is the chief reason for 

 tillage. 



VRoots need air to breathe.! If they cannot get 

 plenty of air, they may stop growing and finally die. 

 This is why trees are often killed by flooding the soil 

 with water, or even by covering it with clay or concrete 

 in making roads or sidewalks. 



When there is plenty of air in the soil, the roots can 

 take up food much more rapidly. 



If the soil is too wet, it must be drained by means of 

 ditches. This lets in air. 



In order to do these things properly, and so help the 

 root in its work, we must know something about the 

 soil itself, and this we will now study. 



