Soil Horizons, Texture and Structure

Topic 2054 Torey Birchmeier

Brian Sobecki

Soil Horizons

3 Horizons

A Horizon B Horizon C Horizon

A Horizon

Common names - Organic layer and top soil Traits

Contains most plant roots Heavily leached from heavy rainfall Contains high organic matter Dark in color

B Horizon

Common name - Subsoil Traits

Zone of acclimation ( Nutrients, silts and clays accumulate in this zone)

Little to No organic matter Red and yellow in color

C Horizon

Common name - Parent material Traits

Below the root zone Outside the Biological zone (Point were no

plant or animals can grow or live)

Texture

Definition: Percentage of sand, silt and clay particles Size of particles.(largest to smallest)

Sand Silt Clay

Texture

Why is texture Important? Water absorption rates Soil water storage capacity Ease of tillage Amount of aeration Soil Fertility

Texture

Determining Soil Texture By Feel Sand

• Coarse gritty feel Silt

• Medium-silty, floury feel Clay

• Fine-sticky when wet

Structure

Definition - the physical arrangement of soil particles Structure affects the movement of water, air

and root penetration

Structure

Types of structures Columns Blocky Granular Plate-like

Structure

Columns Water penetration-good Drainage-good Aeration-good

Structure

Blocky Water Penetration-good Drainage-moderate Aeration-moderate

Structure

Granular Water Penetration-good Drainage-best Aeration-best

Structure

Plate-like Water Penetration-moderate Drainage-moderate Aeration-moderate

References

hpwww.gsfa.nasa.gov/globe/protocol/structure.htm

www.soils.agri.umn.edu/academics/classes/soil3125/doc/2chap3.htm