Soil review

Soil profile

2D section of soil showing the surface to the deepest plant roots

Soil pedon

3D profile of soil that shows all characteristics

Soil horizions

Various layers of soil shown by soil pedon and profile; shows major horizons

Humus

organic debris in soil created from plant and animal litter

O horizion

20-30% organic composition

A horizion

Topsoil organically rich and dark

E horizion

Course sand and silt, leaching removes fine particles

Leaching

Water percolates through soil, removing fine particles and nutrients

Eluviation

Removal of fine particles from upper soil horizions

B horizion

Accumulations of clay, aluminum, and iron via illuviation

Illuviation

Deposition of fine particles from upper soil horizions

C horizon

Weathered bedrock/parent material, few plant roots

R horizion

Consolidated rock or unconsolidated material

Soil structure

Size and shape of particle clumps

Soil texture

Mixture of particle sizes

Loam

Balanced soil mixture (of clay/silt/sand)

Consistence of soil

Cohesion of particles

Porosity

How soil is filled with air/water

Soil colloids

Small particles of clay/organic matter that attract chemicals for plant uptake

Oxisols

Typical soil, low fertility, less distinct horizons

Aridisols

Desert soil, largest coverage, shallow horizons, lack of moisture

Mollisols

Grassland soils significant for agriculture; soft, large, organic

Alfisols

Moderately weathered forest soils, fertile, subsurface clay horizon

Ultisols

Highly weathered forest soils, reddish, not fertile due 2 leaching

Spodosols

Northern coniferous forest soils, sandy parent material

Entisols

Recent, underdeveloped soils, little vertical development

Inceptisols

Weakly developed, young, infertile; usually in moist regimes

Andisols

Volcanic soils, previous soil horizon is buried

Vertisols

Soils high in expandable clays, vertical cracks, moisture variability

Histosols

Accumulation of organic matter, thick peat, largely hydric (saturated w water-anaerobic conditions)

Peat

Accumulation of partially decayed vegetation

Laterization

Soil that is humid, warm, well-drained, and leaches nutrients

Calcification

Arid/semi arid, accumulation of calcium carbonate in lower horizons

Salinization

Desert/semiarid, lots of salts left behind

Podzolization

Cool, moist, leaches with high acidity

Gleization

Cold, wet, poor drainage, humus/clay accumulation