NRES 251: Soil Formation and Physical Properties (Ch 1-4)

What are the 6 types of parent material?

Alluvium, Colluvium, Outwash/Till, Eolian, Residuum, Lacustrine

What is alluvium?

Soil transported by water

What is colluvium?

Soil transported by gravity

What is Outwash/Till?

Soil transported by glaciers

What is the difference between outwash and till?

Outwash is soil spread out like throwing the contents of a bucket. Till is slamming that bucket straight down.

What is eolian?

Soil transported by wind

What is residuum?

Soil that erodes in place. Not transported.

What is lacustrine?

Sediment that settles at the bottom of a lake

What are the 5 forming factors?

Climate, Organisms, Relief, Parent Material, Time

What are the 4 forming processes? Example of each?

What is weathering?

A combination of physical and chemical destruction and synthesis

What are the 3 types of physical weathering?

Abraision, expansion, exfoliation

What are the 5 types of chemical weathering?

Dissolution, Hydrolysis, Carbonation, Oxidation/Reduction, Hydration

What is dissolution?

The mineral comes apart while water stays the same

What is hydrolysis?

When water comes apart and reacts with the mineral

What is carbonation?

When acid increases activity of H+. Causes acidification

What is Oxidation/Reduction?

The loss and gain of electrons

What is soil texture and how is it measured?

The amount of sand, silt, clay, or organic matter in soil. Measures with hydrometer, sieve, lab, or hands.

What does soil texture do for the ecosystem?

Provides water drainage, nutrient holding, weight bearing, particle attraction

Why is surface area important?

More surface area means more capacity to hold water and nutrients.

What does surface area do for the environment?

Provides absorption, nutrient holding, plasticity

What is soil structure?

The arrangement of sand, silt, clay, and organic particles (aggregates/peds)

What do aggregates do for the environment?

They provide microorganisms with a place to live which increases fertility, quality, and prevents compaction.

What is Bulk Density and how is it calculated?

The dry mass divided by total volume. (Mt/Vt)

Why is bulk density important?

It is important for building and agriculture.

What is Particle Density and how is it calculated?

The dry mass of only the solids divided by the total volume (Ms/Vt)

What is porosity?

The volume of air and water in a volume of soil. (Va,w/Vt)

Why is porosity important?

It determines water holding capacity, supports plants, allows drainage, and prevents erosion.

How do you manage porosity?

Through minimized tillage and spreading the weight of foot traffic.

What is the formula for volumetric water content?

0v = Volume of water / Total volume

What is the formula for gravimetric (mass) water content?

0g = Mass of water / Mass of solids

What is hue? What can change it?

The degree of red or yellow. The state of oxides can change it.

What is chroma? What can change it?

The brightness. The state of oxides can change it.

What is value? What can change it?

The lightness or darkness. Changed by organic matter and water.

What are the master horizons?

O - A - E - B - C - R