The Science of the Soil 91 



2. CLASSIFICATION OF SOILS 



Soils are classified in various ways, according to their texture and 

 mechanical composition. Thus such terms as poor, hungry, cold, hot, wet, 

 heavy, light, sour, sweet, are used to denote various conditions; while the 

 terms sandy, clayey, loamy, chalky, marly, and peaty indicate the pre- 

 dominating constituent of a particular soil. 



Several of these terms really mean the same thing to the cultivator. 

 A poor, hungry, light, or hot soil, as a rule, indicates one of a sandy or 

 gravelly nature. Such a soil is " poor " because it is impoverished of plant 

 foods; it is "hungry" because it eats up enormous quantities of organic 

 manures; it is "light", not because of its actual weight, but because it 

 crumbles and falls to pieces easily, and its particles will not cohere and 

 retain sufficient moisture or food; it is "hot" because its gritty particles 

 absorb so much heat during the day that moisture is driven away from the 

 roots of the crops. A " hot " soil also has great variations and fluctuations 

 of temperature, being generally too hot by day in the summer and too cold 

 by night in winter. A hot soil, however, that is well manured and supplied 

 with sufficient moisture is valuable for the production of early crops. 



On the other hand, a cold, wet, heavy soil usually denotes one of an 

 ill-tilled, clayey nature. Such a clayey soil is " cold " because of its 

 "wetness", the heat of the sun being used to dry up the superfluous 

 water instead of being available to warm the soil particles and promote 

 root action. It thus follows that a wet and cold soil is also a "heavy" 

 one, that is, one very difficult to lift, owing to the cohesiveness of its 

 particles, and not so much on account of its actual weight. 



When a cold, wet, and heavy, clayey soil is also full of decaying organic 

 material, and is never deeply cultivated, it then becomes "sour". This 

 sourness is due to the fermentation and decomposition of the organic 

 refuse, which liberates the carbonic acid gas so freely that oxygen is 

 driven out of the soil. A good loamy soil even may be brought into a 

 sour condition by overdressing with stable manure, and by not digging 

 deeply to allow the fresher air to enter and the water to pass away freely 

 to the lower strata. 



To test a soil for sourness or aciditjr, place a small portion into a clean 

 Florence flask, adding enough distilled or filtered rain water to cover it. 

 Boil over a lamp for about fifteen minutes, afterwards allowing the solid 

 matters to settle. Then pour off the clear liquid, and test with a slip of 

 blue litmus paper. If the paper turns red, it is a sign that the soil is sour. 

 To remove the acidity, the soil should be deeply dug, and lime or basic 

 slag added. 



It may be well to say something as to the peculiarities of sand, clay, 

 loam, chalk, lime, peat, and humus. 



Sand. Sand consists of small pieces of hard rock that have been 

 broken down into various degrees of fineness or coarseness from such 



