SOLUM

The upper part of the pedon most influenced by rainfall, roots and microorganisms

SOIL TEXTURE

A description of the ratio of particle sizes, whether sand, silt or clay, within a given soil sample.

SOIL STRUCTURE

A description of how particles are arranged within a given soil sample

HUMUS

Large, complex molecules that remain in the soil as resistant by-products of decay in plant tissue.

COLLOID

A material in the form of fine particles, conferring enormous surface area per unit mass.

What really causes soils to change?

It's the result of energy flow.

What are the main factors of soil formation?

Parent Material, Climate, Organisms(vegetation), Topography & Time

SOIL

(according to a soil scientist)

A particular three-dimensional body of soil materials occuring naturally within a landscape

How are soils related to ecosystems?

A soil is both an ecosystem itself and part of a larger ecosystem. Soils are fundamental to all terrestrial ecosystems, be they urban or rural, highly modified or undisturbed.

M Horizon

A Horizon

C Horizon

R Horizon

ULTISOL

B Horizon

MOLLISOL

SPODOSOL

ALFISOL

What determines soil classification?

W Horizon

Oxisol

E Horizon

Vertisol

ANDISOL

ARIDISOL

INCEPTISOL

GELISOL