106 ELEMENTAKY AGKICULTURE 



how much food is in the soil, the plants will die 

 in the midst of plenty. It is the farmer's task to 

 see that the plant food in his soil is ready for his 

 crops to use, and he tills the soil so that moisture 

 can enter and be kept near the roots. Tillage 

 loosens the soil so air can enter. Tillage also keeps 

 down the weeds that steal the plant food and keep 

 out the sunlight and warmth that the crops need. 

 We can see that a great deal depends upon the 

 farmer's stirring his soil at the right time. 



Keeping Moisture in the Soil. The well-tilled soil 

 is broken into very fine grains or particles (Fig. 55). 

 These fine particles will hold much more water than 

 coarse ones, because each tiny grain has its own 

 coat of moisture. This, you remember, is the reason 

 clay soil will hold more moisture than sandy soil. 

 Clay does not drink it in so rapidly, but it holds on 

 to it better. 



Moisture passes easily from wet grains of earth 

 to dry ones that touch them, so we see that the 

 looser the soil is the fewer are the particles which 

 touch one another. If they do not touch one another, 

 water cannot pass so easily from wet particles to 

 dry ones and in this way climb to the surface and 

 pass off into the air. The surface soil especially 

 must be loose to keep the moisture from evaporat- 

 ing, or getting back into the air. 



The Dust Mulch. The loose layer of surface, 

 which we call dust mulch, acts just like a blanket. 

 Turn over a log or a board in the barn lot in the 



