Revision: the soil class 5th

-- SOIL COMPOSITION

Soil is a complex body composed of five major components :

1. mineral matter obtained by the distintergration and decomposition of rocks;
2. organic matter, obtained by the decay of plant residues, animal remains and microbial tissues;
3. water, obtained from the atmosphere and the reactions in soil (chemical, physical and microbial);
4. air or gases, from atmosphere, reactions of roots, microbes and chemicals in the soil
5. organisms, both big (worms, insects) and small (microbes)

--  THE SOIL PROFILE

The vertical section of the soil that is exposed when a soil pit or a hole is dug from the top surface to the underlying bedrock. 

-- SOIL TEXTURE: 

The look and feel of the soil. It is determined by the size and type of the particles which make up  the soil.

-- SOIL STRUCTURE

The arrangement of the soil particles into larger aggregates of different size and shapes and the pores spaces that are left between them.

http://www.fao.org/fishery/static/FAO

Soil Profile from Saad Farooqi