NRES 251 - Exam I

C.L.O.R.P.T.

CLimate

Organic material

Relief/Topography

Parent material

Time

O.M.W.A.T. — soil needs to…

Organic matter

Minerals

Water

Air

To support/be capable of supporting plant life

How does clay occur?

A chemical reaction.

Lithosphere

rock

Ideal Soil Conditions

• Air 20-30%

• Water 20-30%

• Organic 5%

• Mineral 45%

Macronutrients

• N - Nitrogen

• P - Phosphorous

• K - Potassium

Secondary Nutrients

• S - Sulfur

• Ca - Calcium

• Mg - Magnesium

Micronutrients

• Fe - Iron

• B - Boron

• Na - Sodium

Selenium

While animal, fungal and bacterial life need it, plant life does not. However, plants will still absorb it. Some soil is deficient in selenium, and that can lead to issues such as HIV.  

Physical Factors of Good Soil Quality

• Open/strong structure.

• Deep soil.

Chemical Factors of Good Soil Quality

• Neutral pH.

• Soil fertility.

Biological Factors of Good Soil Quality

• Plenty of organic matter.

• Biodiversity.

Aggregates

Clumps of soil particles.

Alluvium

• Soil transported by water

• Can look pretty different from one place to another. Closer to the river, there’s a higher chance of flooding.

• Rivers have more sand deposits.

• Sorted, layered, and non-uniform thickness.

Colluvium

• Soil transported by gravity

• Ex: mudslide

• Requires a slope, like a hill or mountain.

• Unsorted

Lacustrine

• Lake sediment

• You can have lacustrine deposits in post-glacial lakes, but they look different from glacial lake deposits regarding landscapes. 

• Thinly layered

• Fine texture

• In post-glacial lakes, there might have been living things inside. Not in the glacial lakes, though.

• In post glacial lakes, there are typically a series of alternating dark and light bands that move through the soil called varves.

Eskers

Lakes that had banks of ice a long time ago.

Residuum

• Soil that erodes in place

• Soil formed from bedrock weathering in place. 

• There’s no “nice” way to categorize residuum. 

Aeolian

• Soil transported by air (loess)

• Can be sand/dune forms, or loess, which is wind blown into deposited silt. Silt is easily eroded. 

• Like water in that it sorts particles.

• Generally tilted.

• Silt sized particles

• Little evidence of layers

Glacial deposits

all possible glacial deposits.

• drift/till

• soil transported by glaciers

• Unsorted

• Faceted stones

• Rocks from different places. 

Glacial deposits

• Outwash

• Sorted sand-gravel

• Thickly layered

Parent Material Changes

• Inputs

  • Water

• Losses

  • Water

  • Erosion

  • Minerals getting dissolved

• Translocation

  • Picking up and moving rocks

  • Minerals can get moved downward 

• Transformation

Histosol - factors

• Parent material – organic matter ≥ 40 cm

• Relief

Aridisol

• Arid soil that is dominated by its climatic factors

• Evaporation takes up most of the water

Oxisols

• Soil order that is driven primarily by transformations 

• Fe + Al oxides

Spodosol

• Translocation

• Pine needle tea

O Horizon

• Organic layer

• Greater or equal to 20% of organic matter

• Leaf litter

• Humus

A Horizon

• More mineral material

• Lesser than 20% organic matter

• Topsoil

How can you tell between horizons?

• Color

• Texture

• Lab test

E Horizon

• Greyish-white

• Leaching layer

B Horizon

• Accumulation

• Clay

C Horizon

• Parent material

R Horizon

• Bedrock

Subordinate Distinctions: p

Plow Layer

Subordinate Distinctions: w

Distinctive color without clay accumulation

Subordinate Distinctions: h

Illuvial accumulation of organic matter

Subordinate Distinctions: s

Illuvial organic matter and Fe and Al oxides

Subordinate Distinctions: t

Accumulation of silicate clays

Subordinate Distinctions: g

strong gleying.

Subordinate Distinctions: a

Sapric. (black goo)

Subordinate Distinctions: e

hemic

Subordinate Distinctions: i

Fibrous

Entisol

• Brand new, young

• A, C₁, C₂

Inceptisol

• Teenage soil

• A, B_w, C

(Primarily Coniferous) Spodosol

• O

• E

• Bhs: Fe + Al oxides

• C:

(Primarily Deciduous) Alfisol

• A

• E

• B_t: t - translocated. What’s getting translocated here: clay.

• C

Histosol

• O_i

• O_e

• O_a

• C

Igneous rock

formed from the cooling of molten magma, e.g. granite, basalt.

Sedimentary rock

resulting from deposition or compaction – e.g. sandstone, limestone

Metamorphic rock

formed from changes in igneous or sedimentary rocks due to pressure and temperature. 

• Schist

• Slate

Results of Weathering

• Plant nutrients are released

• Secondary minerals (clay) formed

• Silicon leached out, making soil rich in Al

• Moderately weathered minerals make fertile soil

• Extremely weathered minerals make infertile soil

(Physical weathering) Disintegration

• Abrasion

• Expansion

• Exfoliation

(Chemical Weathering) Dissolution

• Water hydrates ions which are dissociated from each other

• Some minerals plus water = sodium, chloride, and water.

(Chemical Weathering) Hydrolysis

• Water molecules split and H⁺ replaces a cation from mineral structure

• Similar equation to dissolution

(Chemical Weathering) Carbonation

Acid increases the activity of H⁺ in water through the formation of stronger acids. It causes acidification.

(Chemical Weathering) Hydration

• Water combines with a mineral to form a new mineral.

(Chemical Weathering) Oxidation/Reduction

• Oxidation: Loss of electrons. 

• Reduction: Gain of electrons

Results of Weathering

• Plant materials are released

• Secondary minerals (clay) are formed

• Silicon leached out, making soil rich in Al

• Moderately weathered minerals turn to fertile soil

• Extremely weathered minerals turn to infertile soil

Krotovina

a filled-in animal burrow.

Catena

Chain toposequence. A catena in soil science is a series of distinct but co-evolving soils arrayed down a slope.

Chronosequence

 A chronosequence describes a set of ecological sites that share similar attributes but represent different ages.

How many textural classes are there?

12

Heavy Soil

Has more clay in it, and therefore more water. Low D_B

Light Soil

Has more sand in it, and therefore less water. High D_B

Importance of Texture

• Mostly permanent property

• Mapping and classification

• Land use interpretation 

• Water holding and drainage

• Nutrient holding

• Surface area

• Particle attraction

• Porosity

• Expansion and contraction

• Weight bearing

• Organic matter content

Glacial Till - Moraines

• Ground moraines

• Terminal moraines

• Recessional moraines

Rounded Particles

Sand is typically rounded.

Amorphous (Porous)

Humus is mostly porous.

The first stages of soil formation occur because of…?

Biochemical reactions on rock from the excretions of Lichens and Fungi.

Size of soil particles is determined by…?

The diameter.

What is the unit of soil particles?

Milimeters.

(Coarse Earth Fraction) Stones

> 254 mm

(Coarse Earth Fraction) Cobbles

75.5-254 mm

(Coarse Earth Fraction) Gravel

2-75.5 mm

(Fine Coarse Fraction) Sand

0.05-2.00 mm

(Fine Coarse Fraction) Silt

0.002-0.05

(Fine Coarse Fraction) Clay

< 0.002 mm

Humus

< 0.0001 mm

Coarse textures consist of…?

Sands.

Fine textures consist of…?

Clays.

Medium textures consist of…?

Loams.