SOILS 89 



water passes through rapidly. This explains why 

 clay soil is sticky and w^et while sand is a dry soil 

 and almost never forms puddles. 



Holding Water for Plants. It is easy to under- 

 stand how w^ater will move downward through the 

 soil wherever there are openings or pores. We also 

 know that water-coated particles will pass on some 

 of their moisture to dry ones that touch them, just 

 as lamp oil passes up the wick. Thus, you see, mois- 

 ture is always moving toward dry areas. This 

 means a great deal to plants, for when their rootlets 

 drink up the water that is around them and the soil 

 about them is becoming dry, more moisture moves 

 toward the dry place and supplies the thirsty plants. 

 In this way plants may obtain nearly all the water 

 in a good soil. 



Importance of Drainage. Some regions have con- 

 siderable rainfall. Water soon forms a coat about 

 each tiny grain of soil and fills the pore spaces. If 

 more rain keeps falling, and the water cannot pass 

 down easily through the soil, we have swampy land. 

 This happens especially where the under drainage, 

 as we say, is not good. In such swampy lands, the 

 open spaces, or pores of the soil, are always full of 

 water, and no air .can penetrate the soil. 



Good Soil Contains Air. All plants need air about 

 their roots as well as about their stems and leaves. 

 The roots can not do their work without air, and 

 they will not go deeper than the air can follow. 

 Without air, seeds will not sprout, but will rot. 



