Unit 3 Part 4 Soil.ppt

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Soils

Characteristics

Texture

Soil Profile

Soil Types

Threats to Soil

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Soil Characteristics

3 characteristics of soil that affect its value for 3 characteristics of soil that affect its value for

farming and growing vegetation a

farming and growing vegetation are:re:

1.

1. Organic Content

_{Organic Content}

2.

2. Mineral Content

Mineral Content

3.

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Soil Characteristics

1.

1. Organic Content

Organic Content

- A soil's fertility is determined as a ratio

of the organic content to the content of

ground bed rock. Amount of dead and

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Soil Characteristics

2.

2. Mineral Content

Mineral Content

- Varies with precipitation because

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Soil Characteristics

3. Soil Texture (pg. 138)

-

refers to the mixture of fine particles

_{refers to the mixture of fine particles}

(sand),

very fine particles

(silt)

and

extra fine particles

(clay).

The best

texture for agriculture is an even

mixture of each

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Triangular graph of

Soil Texture

_{Soil Texture}

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Soil Profile

(pg. 135-136)

 O Horizon – “Organic”_{O Horizon – “Organic”}  HUMUS:_HUMUS: dead or _{dead or}

decaying plant matter,

leaf litter and other

organic material

organic material lying lying on the surface

on the surface..

 dark_dark because of the _{because of the}

decomposition.

 decompose into _{decompose into}

nutrients

nutrients that enrich the that enrich the soils.

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Soil Profile

 A Horizon – “Topsoil”_{A Horizon – “Topsoil”}  darker than the lower _{darker than the lower}

layers.

 loose_loose and _andcrumbly_crumbly with _with

varying amounts or

organic matter.

 _most_most_productive_productive_{layer of}_{layer of}

soil.

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Soil Profile

 B Horizon – “Subsoil”_{B Horizon – “Subsoil”}  Light colored_{Light colored}, dense, _{, dense,}

and

and low in organiclow in organic matter

matter..

 _materials_materials_{leached from}_{leached from}

the topsoil

the topsoil accumulate accumulate here.

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Soil Profile

 C Horizon – _{C Horizon –}

“Weathered Parent

Material”

 _{transition area}_{transition area}_between_between

soil and parent material.

 _{Partially disintegrated}_{Partially disintegrated}

parent material.

 _mineral_mineral _particles._particles.

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Soil Formation/Advancement

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Differentiate among the terms

Differentiate among the terms humushumus, , leachingleaching, , eluviation

eluviation and and capillary actioncapillary action..

 _Humus_Humus _{is the accumulation of dead and decayed plant and animal}_{is the accumulation of dead and decayed plant and animal}

matter that makes up the

matter that makes up the organic nature of soilorganic nature of soil. Occurs where . Occurs where there is substantial

there is substantial plant and animalplant and animal growth. growth.

 _Leaching_Leaching_{is the process where nutrients are washed down through}_{is the process where nutrients are washed down through}

the soil with the

the soil with the movement of water downmovement of water down the soil profile. Occurs the soil profile. Occurs where there is substantial rainfall.

where there is substantial rainfall.

 _Eluviation_Eluviation _{is the lateral or}_{is the lateral or}_{downward movement of clay and}_{downward movement of clay and} other fine materials

other fine materials in suspension. Occurs where there is in suspension. Occurs where there is

substantial rainfall substantial rainfall..

 _{Capillary action}_{Capillary action} _{results when water molecules are attracted to clay}_{results when water molecules are attracted to clay}

particles and

particles and drawn upwarddrawn upward through the soil profile. Occurs where through the soil profile. Occurs where it is

it is substantially drysubstantially dry. .

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Using the triangular graph of soil texture, which combination would make the poorest soil?

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Using the triangular graph of soil texture, which condition would make the

least favourable soil for farming?

(A) 40% sand, 20% clay, 40% silt

(A) 40% sand, 20% clay, 40% silt (B) 30% sand, 10% clay, 60% silt(B) 30% sand, 10% clay, 60% silt (C) 25% sand, 60% clay, 15% silt

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Using the triangular graph of soil texture, a soil texture combination of

20% sand, 10% clay and 70% silt would constitute which soil type?

(A) sandy clay

(A) sandy clay (B) sandy loam(B) sandy loam (C) silty clay

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Using the triangular graph of soil texture below, which combination would

make the most favourable soil for farming?

(A) 10% sand, 15% clay, 75% silt

(A) 10% sand, 15% clay, 75% silt (B) 15% sand, 55% clay, 30% silt(B) 15% sand, 55% clay, 30% silt (C) 20% sand, 70% clay, 10% silt

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Which process transports insoluble inorganic matter downward through the soil?

A) accumulation of humus B) capillary action

C) eluviation D) leaching

Which term refers to the process by which particles of insoluble inorganic matter are transported downward through the

soil?

(A) accumulation of humus (B) capillary action

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Which refers to the upward movement of soluble material Which refers to the upward movement of soluble material

through the soil by water? through the soil by water?

(A) capillary action (A) capillary action (B) eluviation (B) eluviation (C) erosion (C) erosion (D) leaching (D) leaching

Which term refers to the process by which minerals and Which term refers to the process by which minerals and

dissolved salts are transported upward through the soil? dissolved salts are transported upward through the soil?

(A) accumulation of humus (A) accumulation of humus (B) capillary action

(B) capillary action (C) eluviation

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3 types of Soil

pg. 136-137

1.

Latosol

2.

Podzol

3.

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Latosol

 Typically in _{Typically in}tropical rainforest_{tropical rainforest}._.  Very deep, very well drained, _{Very deep, very well drained,}

homogeneous.

 Infertile_Infertile due to…._{due to….}

- Highly

- Highly weatheredweathered and and

leached

leached soils because of high soils because of high amounts of

amounts of rainfallrainfall. .

 They tend to have medium to _{They tend to have medium to}

very high

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Podzol

 Typically found in the Typically found in the Boreal Boreal

forest

forest..

 Extends immediately Extends immediately south south

of the tundra

of the tundra regions of the Northern regions of the Northern Hemisphere.

Hemisphere.

 Gray in color, ashy appearance.Gray in color, ashy appearance.  Often Often severely leachedseverely leached and and

highly acidic.

 They are They are low in agricultural low in agricultural

value, forests

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Chernozem

 _{Rich in organic matter in the}_{Rich in organic matter in the}

form of

form of humushumus. .

 _{True chernozem is}_{True chernozem is}_{black in}_{black in}

color.

 _{They are found in}_{They are found in}_grasslands_grasslands

which are

which are semi-aridsemi-arid……

 Resulting in _{Resulting in}less leaching_{less leaching} and a _{and a}

mineral rich soil

mineral rich soil. .

 _{It is}_{It is}_{very suitable for}_{very suitable for}

agriculture

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Threats to Soil

Environmental

Factors:

1. Temperature

- affects

- affects humus humus (low temps. slow the (low temps. slow the decay

decay of organic matter).of organic matter).

2.

2. Precipitation

Precipitation

- affects

- affects mineral contentmineral content (rain causes (rain causes minerals to be eluviated).

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Threats to Soil

pg. 140-143

• Poor soil management_{Poor soil management}

- agricultural areas and

grasslands.

• Urban Expansion_{Urban Expansion}

- settling in rich farmland

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Threats to Soil

•

Desertification

–

the spread of desert-like

conditions in semi-arid environments

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Threats to Soil

•

Flooding

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Reducing Soil Erosion

Pg. 142

Soil Erosion can be reduced by:

1. Strip cropping

• Alternating strips of open-growing crops and close-growing crops.

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Reducing Soil Erosion

2. Cover cropping

• When soil is ready to use, this crop gets ploughed back into the soil, increasing the humus content. • Planting close-growing

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Reducing Soil Erosion

3. Contour ploughing

• Respects the natural shape of the land and

forms

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Reducing Soil Erosion

4. Terracing

• Constructing steps or shelves in the sides of hills or sloping land to reduce water run-off and retain