Soil as a system

Soil consists of mineral matter, organic matter, air, and water
Dead and living microorganisms, and decaying material
Bacteria, algae, earthworms, insects, mammals, amphibians, and reptiles

Soil consists of mostly mineral matter
varying proportions of organic matter
Rest is pore space taken up by air, water, and other soil gases
Parent material = the base geologic material of soil
Mineral content
Determines the starting composition of the soil

Organic matter includes living and dead microorganisms as well as decaying plant and animal material
Water – is not pure, contains dissolved minerals and organics and is important for support of plant growth
Air – soil air is not the same as air we breathe
Soil can have an influence on a region’s ecosystem

Soil formation begins when parent material is exposed to the effects of the atmosphere, hydrosphere, and biosphere
Parent material can be lava, volcanic ash, rock, dunes or most commonly, bedrock
Bedrock is the continuous mass of solid rock comprising the Earth’s crust

Weathering = the physical, chemical, or biological processes that break down rocks to form soil
Physical (mechanical) = wind and rain, no chemical changes in the parent material
Chemical = substances chemically interact with parent material
Biological = organisms break down parent material