Introduction to Soils

what is soil?

• mixture of minerals and organic matter

• composed of grains and pore spaces containing air or water

Soil is known as a unconsolidated deposit, what does this mean?

loose sediment that has not been cemented or compacted into solid rock.

where is soil in terms of the earth structure?

• outermost layer of the geosphere

• innermost layer of the biosphere

Why is soil known as the critical zone?

• site of processes controlling major element cycling

what are three main functions of soil?

• growth medium

• habitat

• carbon/water store

How is soil formed?

• soils form through weathering of underlying parent material and the deposition of material from above

what 5 factors control the varied distribution of soil types across the world?

• climate

• organisms

• relief/ topography

• parent material

• time

How does climate affect soil formation?

• affects the physical, chemical and biological processes controlling soil formation

i.e

• chemical weathering / leaching

• freeze thaw

• organic matter formation

• precipitation of secondary minerals including clays and salts