282 NATURE STUDY AND AGRICULTURE 



Does this have water standing in it ? Where is the moist- 

 ure ? This is called capillary water because it is found in 

 the pores of the soil. It is sometimes called film water, 

 because it forms a film around each particle. 



Put a smooth pebble into some water. Take it out 

 and you can see a layer of water around it. This illus- 

 trates how each tiny particle of the soil holds a film of 

 moisture. Capillary water is that which is used by the 

 plants. 



There is another form in which water is found in the 

 soil. This form is known as hygroscopic water. This is 

 held so firmly around the soil particles that it is very hard 

 to remove. Put a little very fine dry soil into a test tube 

 and heat it to a high temperature over the alcohol lamp. 

 What evidence have you that this dry soil had some 

 moisture in it? 



Do different kinds of soil influence the amount of water 

 that soaks into the ground, and the amount retained? 

 Before answering this question let us become better ac- 

 quainted with the different soils. You have in your col- 

 lection several different kinds of soil; gravel, sand, silt or 

 clay, loam, and humus. Which is composed of the 

 coarsest particles ? Rub a little of each kind between your 

 thumb and finger. How do they differ? If you have a 

 lens, spread a little of each on white paper and examine 

 carefully. How do the particles of sand look ? Note the 

 jagged edges of the hardest particles. Can you find any 

 sand particles in the loam? In the clay? 



Place some sand in a large iron spoon and heat it red 

 hot over the alcohol lamp? Does it burn? Try clay, 

 humus, loam. Which ones burn? It is the organic 



