Introduction to Soils Laboratory Exercise #1 By: Carlin Conk

Introduction to SoilsIntroduction to Soils

Laboratory Exercise #1Laboratory Exercise #1

By: Carlin ConkBy: Carlin Conk

Definition of SoilsDefinition of Soils

Soil is the collection of natural bodies on earth’s Soil is the collection of natural bodies on earth’s surface containing living matter and supporting, or surface containing living matter and supporting, or capable of supporting plants. Its upper limit is the capable of supporting plants. Its upper limit is the atmosphere (air) or water, and at its lateral margins atmosphere (air) or water, and at its lateral margins it grades to deep water or barren areas of rock and it grades to deep water or barren areas of rock and ice. Its lower limit is normally considered to be the ice. Its lower limit is normally considered to be the lower limit of the common rooting zone (root zone) of lower limit of the common rooting zone (root zone) of the native perennial plants, a boundary that is the native perennial plants, a boundary that is shallow in the deserts and tundra and deep in the shallow in the deserts and tundra and deep in the humid tropics.humid tropics.

Soil ProfileSoil Profile

A A soil profilesoil profile is the is the vertical display of vertical display of soil horizons.soil horizons.

epod.usra.edu/archive/images/

100_3733.jpg

OOAA

EE

BB

Soil PedonSoil Pedon

PedonPedon is a 3-D unit that is a 3-D unit that represents the entire soil represents the entire soil body and is the smallest body and is the smallest volume of soil that volume of soil that shows all of the shows all of the characteristic properties characteristic properties of a particular soil.of a particular soil.

Typically represents 10-Typically represents 10-100 ft100 ft22 of surface area. of surface area.

A group of pedons is A group of pedons is calles calles polypedons.polypedons. www.soils.umn.edu

Soil SeriesSoil Series

A A soil seriessoil series includes soils that have developed from includes soils that have developed from similar materials by similar processes resulting in similar materials by similar processes resulting in similar appearances and properties.similar appearances and properties.

The characteristic properties of a soil series are The characteristic properties of a soil series are unique.unique.

There are more than 20,000 soil series in the United There are more than 20,000 soil series in the United States.States.

Soil Series ExampleSoil Series Example

http://ilmbwww.gov.bc.ca/risc/pubs/teecolo/soil/soil-1.htm

Soil ColorSoil Color

Soil color can suggest soil properties that may Soil color can suggest soil properties that may influence plants.influence plants.

Dark soil near the surface may indicate a high Dark soil near the surface may indicate a high organic matter content, which may lead to organic matter content, which may lead to easier cultivation and higher nutrient content.easier cultivation and higher nutrient content.

Soil Color in Young & Old SoilsSoil Color in Young & Old Soils

A young, unweathered soil may have a soil of A young, unweathered soil may have a soil of uniform color.uniform color.

In older, weathered soils, yellow and red In older, weathered soils, yellow and red colors may dominate well below the surface of colors may dominate well below the surface of the soil.the soil.

In North Carolina, we typically have bright red In North Carolina, we typically have bright red subsoils, would this indicate young or old subsoils, would this indicate young or old soils? Weathered or unweathered? soils? Weathered or unweathered?

Soil Forming FactorsSoil Forming Factors

CL - ClimateCL - Climate OR - OrganismsOR - Organisms P - Parent MaterialP - Parent Material T - TimeT - Time T – TopographyT – Topography

==CLORPTTCLORPTT (an easier way to remember the (an easier way to remember the soil forming factors)soil forming factors)

ClimateClimate

ClimateClimate refers to rainfall and temperature. refers to rainfall and temperature. The main effects are: weathering, the The main effects are: weathering, the

production of organic matter , and the production of organic matter , and the decomposition of organic matter.decomposition of organic matter.

Climate of North CarolinaClimate of North Carolina

In North Carolina, rainfall is fairly similar across the In North Carolina, rainfall is fairly similar across the Piedmont and Coastal Plain. However, the rainfall is Piedmont and Coastal Plain. However, the rainfall is more variable in the mountains of North Carolina.more variable in the mountains of North Carolina.

http://www.ocs.orst.edu/pub/maps/Precipitation/Total/States/NC/nc.gif

Mountain Piedmont Coastal Plain

Organisms or Biotic ActivityOrganisms or Biotic Activity

Vegetation is the main Vegetation is the main biotic factorbiotic factor.. The type of vegetation affects the soil color The type of vegetation affects the soil color

and organic matter content, especially in the A and organic matter content, especially in the A (or top) horizon.(or top) horizon.

Grasslands vs. ForestsGrasslands vs. Forests

Trees contribute less organic matter to the soil each Trees contribute less organic matter to the soil each year when compared to grasslands.year when compared to grasslands.

The top horizons, or A horizons, in forests are The top horizons, or A horizons, in forests are usually thinner than A horizons in grasslands.usually thinner than A horizons in grasslands.

http://www.soils.umn.edu/academics/classes/soil2125/doc/s10chap1.htm

OM content

Parent MaterialParent Material

Parent materialsParent materials are defined as the materials are defined as the materials underlying the soil and from which the soil underlying the soil and from which the soil developed.developed.

There are many different parent materials, including:There are many different parent materials, including:

Residual minerals and rocks (bedrock)Residual minerals and rocks (bedrock)

Glacial depositsGlacial deposits

Loess depositsLoess deposits

Alluvial and marine depositsAlluvial and marine deposits

Organic depositsOrganic deposits

Residual Rocks and MineralsResidual Rocks and Minerals

Residual minerals weather in place to form soils.Residual minerals weather in place to form soils.

Bedrock

Soil

http://www.gly.uga.edu/railsback/FieldImages.html

Glacial DepositsGlacial Deposits Glacial deposits formed as Glacial deposits formed as

massive ice sheets, moving massive ice sheets, moving across North America, across North America, approximately one million approximately one million years ago.years ago.

As the glaciers expanded, As the glaciers expanded, they "bulldozed" rocks, they "bulldozed" rocks, minerals and soil in front of minerals and soil in front of them. them.

As the ice sheets melted, the As the ice sheets melted, the exposed parent material exposed parent material began to weather and soil began to weather and soil was formed. was formed.

http://www.soils.umn.edu/academics/classes/soil2125/img/1usglac.jpg

Glacial SoilsGlacial Soils

Boulders and RocksBoulders and Rocks

Loess DepositsLoess Deposits

Loess depositsLoess deposits formed as high speed winds formed as high speed winds picked up predominantly silt-sized particles picked up predominantly silt-sized particles and carried them across open areas. and carried them across open areas.

As the wind speed slowed the particles fell to As the wind speed slowed the particles fell to the ground covering the native soil and parent the ground covering the native soil and parent material. material.

Loess Deposits ExampleLoess Deposits Example

http://esp.cr.usgs.gov/info/eolian/11aNew.jpg

Alluvial DepositsAlluvial Deposits Alluvial depositsAlluvial deposits

refer to sediments refer to sediments carried by and carried by and deposited in fresh deposited in fresh water. water.

Flooding events Flooding events carry rocks and carry rocks and minerals, which minerals, which are deposited in are deposited in bands.bands.

http://cee.engr.ucdavis.edu/faculty/boulanger/geo_photo_album

Marine DepositsMarine Deposits

Marine sedimentsMarine sediments refer refer to sediments carried by to sediments carried by fresh water but fresh water but deposited in salt water. deposited in salt water.

Marine sediments can Marine sediments can build up over long build up over long periods of time until periods of time until eventually they are quite eventually they are quite deep. deep.

http://www.mo15.nrcs.usda.gov/features/gallery/bonneau.jpg

Organic DepositsOrganic Deposits

Organic depositsOrganic deposits originate from plants that originate from plants that have died or shed their leaves. have died or shed their leaves.

Organic deposits are common to areas such as Organic deposits are common to areas such as swamps and marshes since the chemical and swamps and marshes since the chemical and biological process that decompose the organic biological process that decompose the organic matter are greatly limited by the saturated matter are greatly limited by the saturated conditions conditions

Organic Soils of North CarolinaOrganic Soils of North Carolina

http://soils.usda.gov/technical/classification/orders/images/histosol.jpg

http://www.soil.ncsu.edu/publications/Soilfacts/AG-439-26/image2.gif

Time as a Soil Forming FactorTime as a Soil Forming Factor

We may regard time as continuous yet still We may regard time as continuous yet still recognize a "time zero" for a given soil. recognize a "time zero" for a given soil.

Time zeroTime zero is the point in time at which a is the point in time at which a catastrophic event (flood or earthquake) is catastrophic event (flood or earthquake) is completed and a new cycle of soil completed and a new cycle of soil development is initiated. development is initiated.

Time is important in soil formation because it Time is important in soil formation because it determines the degree to which the other soil determines the degree to which the other soil forming factors express themselves. forming factors express themselves.

““Old” SoilsOld” Soils

"Old" soils are those "Old" soils are those that have experienced that have experienced intense weathering of intense weathering of parent material in the parent material in the presence of biotic presence of biotic factors. These soils will factors. These soils will have well developed have well developed profiles containing A, E, profiles containing A, E, and B horizons. and B horizons.

http://soils.ag.uidaho.edu/soilorders/spodosols_02.htm

““Young” SoilsYoung” Soils

Young soils have Young soils have weakly developed weakly developed horizons and may often horizons and may often lack E and B horizons. lack E and B horizons.

This soil profile lacks This soil profile lacks any horizon any horizon development.development.

http://soils.usda.gov/technical/classification/orders/entisols.html

Absolute AgeAbsolute Age

If the absolute ageIf the absolute age of a soil is of interest, a soil of a soil is of interest, a soil scientist may measure the activity of scientist may measure the activity of radioactive carbon. radioactive carbon.

Knowing the activity of the radioactive carbon Knowing the activity of the radioactive carbon the scientist can estimate the age of the parent the scientist can estimate the age of the parent material that has been subjected to weathering. material that has been subjected to weathering.

TopographyTopography

Topography consists of three parts: elevation, Topography consists of three parts: elevation, slope, and aspect. slope, and aspect.

Slope is the tilt or inclination of the land.Slope is the tilt or inclination of the land. Elevation is the height above mean sea level.Elevation is the height above mean sea level. Aspect is the direction the slope is facing. Aspect is the direction the slope is facing.

Soils on a Steep SlopeSoils on a Steep Slope

As slopes increase, soils As slopes increase, soils become shallower and become shallower and have thinner and fewer have thinner and fewer horizons. horizons.

This is because the This is because the steeper the slope the steeper the slope the greater the runoff and greater the runoff and the greater the erosion. the greater the erosion.

http://soils.ag.uidaho.edu/soilorders/inceptisols_05.htm

Review of Soil Forming FactorsReview of Soil Forming Factors

ClimateClimate OrganismsOrganisms Parent MaterialParent Material TimeTime TopographyTopography

Describing SoilsDescribing Soils

As a soil develops on the landscape, distinct layers or As a soil develops on the landscape, distinct layers or bands parallel to the earth's surface may form. bands parallel to the earth's surface may form.

These layers or bands are called soil horizons. These layers or bands are called soil horizons. Soil horizonsSoil horizons,, are soil layers that differ from the are soil layers that differ from the

overlying and underlying layers in some property, overlying and underlying layers in some property, such as color, clay content, abundance of cracks, etc.such as color, clay content, abundance of cracks, etc.

Color is one property that is commonly used to Color is one property that is commonly used to separate different soil horizons. separate different soil horizons.

Soil Horizon & Layer DesignationSoil Horizon & Layer Designation

In the United States, soil horizons are In the United States, soil horizons are designated by a code of letters and numbers designated by a code of letters and numbers developed by soil scientists of the National developed by soil scientists of the National Cooperative Soil Survey.Cooperative Soil Survey.

Master horizonsMaster horizons are major layers designated are major layers designated by capital letter such as 0, A, E, B, C and R. by capital letter such as 0, A, E, B, C and R.

Master Horizons – O HorizonMaster Horizons – O Horizon 0 0 Horizon:Horizon: Organic Organic

horizons are dominated by horizons are dominated by organic material. organic material.

The 0 horizons contain The 0 horizons contain organic litter from plants organic litter from plants and animals. and animals.

0 horizons are usually 0 horizons are usually present on the soil surface present on the soil surface except in the case of peats except in the case of peats and mucks where the 0 and mucks where the 0 horizon extends almost to horizon extends almost to the bottom of the soil.the bottom of the soil.

http://aggieturf.tamu.edu/aggieturf2/golf/layering.html

O Horizon

Master Horizon – A HorizonMaster Horizon – A Horizon A HorizonA Horizon : : Mineral Mineral

horizons that have formed at horizons that have formed at the soil surface or just the soil surface or just below the 0 horizon.below the 0 horizon.

The A horizon may contain The A horizon may contain some organic material some organic material mixed with mineral mixed with mineral material.material.

Properties of the A horizon Properties of the A horizon may reflect plowing, may reflect plowing, pasturing or similar pasturing or similar activities. activities.


Master Horizon – E HorizonMaster Horizon – E Horizon E HorizonE Horizon : : Mineral horizon Mineral horizon

in which the major in which the major characteristic is loss of clay, characteristic is loss of clay, iron and aluminum oxides iron and aluminum oxides by by eluviation eluviation or leaching. or leaching.

An increase in concentration An increase in concentration of sand and silt size of sand and silt size particles of resistant particles of resistant minerals occurs as clay is minerals occurs as clay is leached to lower depths. leached to lower depths.

Color is lighter than the Color is lighter than the overlying A horizon. overlying A horizon.


Master Horizon – B HorizonMaster Horizon – B Horizon

B Horizon:B Horizon: Mineral Mineral horizon that includes horizon that includes layers in which layers in which illuviationilluviation or or accumulation of accumulation of materials has taken materials has taken place. place.

Clay, iron and Clay, iron and aluminum oxides from aluminum oxides from the overlying E horizon the overlying E horizon have accumulated here.have accumulated here.

http://soils.ag.uidaho.edu/soilorders/ultisols_04.htm

Master Horizon – C & R HorizonsMaster Horizon – C & R Horizons

C C Horizon:Horizon: Mineral horizon Mineral horizon consisting of consisting of unconsolidated, partially unconsolidated, partially weathered material that is weathered material that is neither soil or rock. neither soil or rock.

The horizon is below the The horizon is below the zone of most biological zone of most biological activity. The upper layer of activity. The upper layer of the C horizon may become the C horizon may become part of the B horizon as part of the B horizon as weathering continues.weathering continues.

R Layer:R Layer: Underlying Underlying consolidated bedrockconsolidated bedrock


Transitional HorizonsTransitional Horizons

Transitional horizonsTransitional horizons are layers of soil are layers of soil between two master between two master horizons. horizons.


Subordinate DistinctionsSubordinate Distinctions

Subordinate distinctionsSubordinate distinctions are specific features are specific features within master horizons within master horizons that are designated by that are designated by lowercase letters. lowercase letters.

There are many There are many subordinate distinctions subordinate distinctions such as:such as:p – plow layerp – plow layer

t – accumulation of clayt – accumulation of clay b – buried layerb – buried layer


Questions?Questions?

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Introduction to Soils Laboratory Exercise #1 By: Carlin Conk