CHAPTER III 

 PHYSICAL PROPERTIES OF SOILS 



By physical properties are meant weight, color, tempera- 

 ture, and the way in which air and water circulate through 

 the soil. 



Weight. — The weight of a soil depends upon what it is 

 derived from. A cubic foot of sandy soil will weigh more 

 than a cubic foot of loam, and a cubic foot of loam is heavier 

 than a like amount of muck. The sandy soil is composed 

 almost entirely of hard flinty or quartz rock particles, which 

 have very little vegetable matter among them. The loam 

 contains, besides the quartz particles, many particles of rock 

 not so hard nor so heavy. The loam has also much more 

 organic matter in it than there is in the sand. Muck is rather 

 light, because it is made up so largely of organic matter and 

 has so little of rock particles. A cubic foot of dry soil will 

 weigh about as follows : sandy about 95 to 100 pounds, clay 

 70 to 80 pounds, loam 65 to 75 pounds, and muck 30 to 40 

 pounds. Sandy soils are the heaviest of all soils by weight, 

 but farmers speak of them as being light because they are 

 easily plowed and cultivated; clay soils are said to be heavy 

 because they are difficult to plow and cultivate. 



Color. — The color of soils is variable and is not a very 



certain sign of their fertility. Sands are generally grayish or 



yellowish. Clays may be whitish, yellow, red or bluish. 



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