SCSC test 3

What do the Youngest soils have?

• NoBhorizon:AC(ent)

• Weakly developedBhorizon,Bw(ept)

What do Pretty Young soils have?

• Arid climates with Bk, By, Bz horizons (id)

• Volcanic soils (and)

• Frozen soils (el)

• Organic soils (ist)

What do medium develiped soils have?

• Grassland/prairie soils: deep, dark A horizon (high base status) (ol)

• Shrink/swell clay soils: clay throughout profile, Bss (high base status) (ert)

• Savanah soils: Bt horizons (high base status) (alf)

• Acidic, sandy, coniferous forest soils: Bhs (od

What do well developed soil have?

• Forest soils: Bt horizons (moderately high to low base status) (ult)

• Tropical soils: Bo horizons (low base status) (ox)

soil formation process from newest to oldest. 9 Steps

1. Physical disintegration of rock

2. Chemical alteration of the rock

3. Changes in mineral distribution

4. Formation of secondary minerals

5. Appearance of higher plants

6. Development of soil structure

7. Leaching of bases becomes significant

8. Downward movement of clay

9. Fe/Al Oxides are the remaining

minerals

eluviation

seen in E horizons eluviation (loss) of

clay, Fe and Al oxides,

O Horizons, and sub distintions, most decomposed least decomposed

– Shallow O horizons usually present in forests– Generally absent in grassland soils– Needs to be mostly organic material, this is not the same as organic matter found

in the A horizon.

-(they are based on the degragation of organic matter) (decending alphabet order.)

• Oi (slightly decomposed = fibric)

• Oe (moderately decomposed = hemic)

• Oa (highly decomposed = sapric)

A Horizons

• Topmost mineral horizon, Rich in OM but not mostly composed of it

• Enriched with decomposed (humified) organic matter to give soil darker color

• Often coarser in texture (i.e., sandier) than other horizons due to

translocation and erosion of finer particles

• Most common subordinate A horizon– Ap -Plowing or other disturbance

E Horizons

• Zones of maximum leaching or eluviation (loss) of

clay, Fe and Al oxides

• Remaining materials are generally composed of quartz

and is light in color than A or B horizons– Albic

• Common in forest soils, but not in grassland soils

B Horizons

The loss (eluveation) went down to this horizon

• Different from original parent material

• Usually a zone of accumulation (or illuviation) – or change in color and/or structure from

Subordinate B horizons

bw, bt, Bo, Bhs, Btn, Bk, By, Bss

– Bw = no accumulation, but weakly weathered with changes in color and/or structure from A

– Bt = accumulation of clay, (T=clay)

– Bo = accumulation of Fe and Al oxides

– Bhs = accumulation of humus, Fe and Al oxides (red humus)

– Btn = accumulation of clay and sodium

– Bk = accumulation of carbonates (CaCO3) (k for carbonates)

– By = accumulation of gypsum (CaSO4∙H2O)

– Bss = presence of slickenside

C horizon

• Unconsolidated material underlying the solum

• Cr = soft bedrock

R horizon

• Consolidated rock with little evidence of weathering

• Hard bedrock

Where are the zones of eluviation and illuviatior

qualities inherited from parent material

– Mineralogy

– Texture

– pH

– Stratification

Qualities acquired by soil formationprocesses (also can be managed)

– Structure

– Organic matter (color value)

– Horizonation

Pedon

is the individual

Polypedon

is a group of similar individuals

Soil Series

is a class of soils with similar characteristics

Soil Taxonomy

is a classification scheme for soil

– Based on soil properties that can be objectively observed or measured

– Name has meaning for the major characteristics of the soi

Epipedons

Diagnostic Surface Horizons ( O & A)

Endopedons

diagnostic Subsurface Horizons– (E and B)

What are the 4 epipedons?

• Mollic (A)

• Umbric (A)

• Ochric (A)

• Histic (O)

Mollic (A)

Dark, high bases

Umbric (A

Dark , low bases

Histic (O)

near 100% organic

Ochric (A)

If you are trying to guess a soil with a value of less than 4 look at organic matter content, then high or low bases. If it’s not these 3, then it’s ochric.

Albic (E)

• E horizon

• Maximum zone of eluviation

• Albino, white

Cambic (Bw)

• Weakly weathered or weakly developed

• Usually only changes in color or structure (no accumulation)

• Cambiare, to exchange, change

Argillic (Bt)

• Accumulation of clays with high bases

• Argilla, clay

Kandic (Bt, Bts)

• Accumulation of clays with low bases (e.g., kaolinite)

• “old clay”

Spodic (Bh, Bs)

– Illuvial horizon with humus and Fe/Al oxides

– Forms in highly leached forest soils of cool humid

climates

– (easy to identify: Only dark/black horizon under E)

If you see somthign dark under e its prob bh or bs

Oxic (Bo)

ozides= old soil, last to develop

– Illuvial zone of oxides, 1:1 clays and very few weatherable minerals

• Calcic (Bk)

calcium carbonate (CaCO3)

Petrocalcic (Bkm)

– calcium carbonate that is cemented– Petro, rock, m for massive

Gypsic (By)

– gypsum (CaSO4H2O)

Petrogypsic (Bym)

– gypsum that is cemented

Salic (Bz)

– soluble salts– Sal, salt

Natric (Btn) –

clay with high levels of Na Natrium, sodium, bt= the clay n = the sodium

Entisols (ent)

VERY young, A and C only, ochric surface horizon

Inceptisols (ept)

Young soil; cambic horizon (Bw)

A over Bw

Mollisol (oll)

Mollic epipedon; high bases; dark, soft

grasses mollify

Alfisol (alf)

Argillic high bases

Alfisoil and argillic have A and L

Ultisol (ult)

Kandic horizon; low bases; moderately high weathering

• Subsurface: kandic**

Oxisol (ox)

Oxic epipedon; highly weathered

• Subsurface: oxic

Vertisol (ert)

High in swelling clays (>30%); deep cracks when dry; slickensides; can have mollic or argillic horizons

swelling clay with cracks

Aridisol (id)

Dry climate, usually ochric

aird

Spodosol (od)

Spodic horizon

Histosols (ist)

Organic O horizon, abput 80 cm of organic soil

Andisol (and)

volcanic ash

Gelisol (el)

permafrost)

A= R K (LS) C P

annnual, rainfall, erodibility, slope lengh, steepness, crop cover, pracices to prevent erosion

land use capability classes e, w, s, c,

Erosion, wet, (shallow) root zone, climate.