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BOTANY 



Inorganic soil is being formed by weathering. 



that once upon a time at least 

 apart of the earth was molten. 

 Later, it cooled into solid rock. 

 Soil-making began when the 

 ice and frost, working with the 

 heat, chipped off pieces of rock. 

 These pieces in time became 

 ground into fragments by action 

 of ice, glaciers, or the atmos- 

 phere. This process is called 

 weathering. Weathering is 

 largely a process of oxidation. 

 A glance at crumbling stone 

 will convince you of this, be- 

 cause of the oxide of iron (rust) disclosed. So by slow degrees this earth 

 became covered with a coating of what we call inorganic soil. Later, gen- 

 eration after generation of tiny plants and animals which lived in the 

 soil died, and their remains formed the first organic materials of the soil. 



You are all familiar 

 with the difference be- 

 tween the so-called rich 

 soil and poor soil. The 

 dark soil simply contains 

 more dead plant and 

 animal life, which forms 

 the portion called humus. 

 A simple experiment 

 may be performed to 

 show the amount of vege- 

 table and mineral mat- 

 ter in different soils. 



Amount of Organic 

 Matter in Soil. — Gather 

 about a pound of leaf 

 mold from a forest, a like 

 amount of the rich loam 

 taken from beneath the 

 leaf mold, and the same 

 amount of soil taken from 

 a barren roadside or 

 field. Dry them carefully 

 and then weigh equal 

 amounts (say 100 grams) 

 of each kind of soil. 

 Place them on pieces of 



tin and heat them red- This picture shows how the forests help to cover the 



hot over a coal fire or in inorganic soil with an organic coating. 



