EXERCISE A-10. TO STUDY SOIL GRANULATION. 



Equipment: Three shallow pans; sample of heavy 

 clay soil. 



Method: Fill each of three pans nearly level full with 

 dry clay soil. To the first pan add all the water which 

 it will hold, continuing to pour on water as it soaks in, 

 while working the soil with the fingers or with a stick. 

 Over the second pan sprinkle one-half cup of water. Leave 

 the third pan untreated. Place all three pans near a 

 stove or in the sun, and dry thoroughly. Compare the 

 size of the lumps of soil in the pans to which water was 

 added., Which crumbles more easily between the fmgers? 

 Which is more like a field in good tilth? What happened 

 to the first pan? 



Discussion: The fine rock particles in a pile of clean 

 sand always remain separate, but the very, very fine par- 

 ticles of rock which form the soil stick together to form 

 crumbs or granules. When these granules are comparativel}^ 

 small and easily crushed, the soil is said to be ivcll granulated. 

 Large hard granules are called clods. When a large amount 

 of water is added to a clay soil, the soil becomes " puddled " 

 or " run together," and clods are formed. Similarly, if a 

 wet clay soil is compacted by the feet of men or horses, 

 or if it is plowed when too wet, hard clods are formed. 



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