FACTORS AFFECTING SOIL FORMATION

Climate

Most important factor

It determines

Rate of weathering + biological activity

Hot climates

Rapid chemical weathering + decomposition of organic matter

Cold climates

Less biological activity + freeze-thaw action

Wet climates

Leaching + waterlogging

Dry climates

Draught + evaporation leads to salinisation and calcification

Salinisation and calcification

Build up of salt and calcium

Ex. (salinisation and calcification)

Saltpans of Botswana and Bonneville Salt Flats

Parent Material

Original bedrock

This is where

Mineral matter in the soil first developed

Different rocks develop

Different soil characteristics

Igneous rock develops

Acidic soils

Sedimentary rock develops

Large variety

Topography

Soil formation is affected by gradient, altitude and aspect

Each of these affect

Depth and drainage of soil

Flat upland areas tend to be

Cold and wet (waterlogging)

Sloping land tend to experience

Soil erosion (much thinner)

Low lying flat areas tend to be

Abundant in humus (fertile)

Number of organisms determine

The fertility of soil

Decomposition of what occurs

Organic material (plant roots, burrowing animals, bacteria)

Animals such as rabbits

Help aerate and mix the soil as they burrow through horizons

Fungi and bacteria lead to

Humification

Time

Soils take a very long time to form

Young soil

Not well developed

Older soil

Well developed profiles

Most of Ireland’s soils are

Less than 10,000 y/o