soils

what factors influen the soil formation?

parent material, climate, organisms, topography, and time

know different weathering processes

Physical weathering breaks rocks down, often through temperature changes or water action.

Chemical weathering involves chemical reactions that alter the mineral composition of rocks, such as dissolution or oxidation.

Biological weathering occurs when living organisms, like plants and animals, contribute to the breakdown of rocks

know transported materials by wind, water, gravity, etc

Wind erosion transports sand, soil, dust and soluble compounds in arid regions

water erosion is capable of transporting a wide range of particles like sand, gravel, or even boulders

Gravity moves materials downslope, landslides, mudflows, etc

Ice/glaciers transport enormous amounts of sediment

how are organic maerials deposited? can you explain the steps/processes

Organic matter deposition involves several steps, starting with the initial source of organic material, like plants or microorganisms, then their breakdown or secretion into the environment, and finally their accumulation and transformation into sediment or soil organic matter

what are principal climatic variables

temperature and effectibe precipitation

Define effective precipitation

to be effective in the soil formation, water must penetrate regolith. the freater depth of penetration, the greater the depth of weathering soil and development

beside the climate facotr, what are four factors that influence the soil formation?

Parent Material: The type of rock and mineral material from which soil develops significantly influences its characteristics.For instance, soil derived from acidic parent rocks will tend to be acidic, and soil from sedimentary rocks may contain more clay

Topography (Relief): The slope, elevation, and exposure of the land affect soil formation. Steeper slopes promote erosion, leading to thinner soil layers, while flatter areas may have thicker soil accumulations

Organisms: Living organisms, including plants, animals, and microorganisms, contribute to soil formation and health.Plants add organic matter to the soil through leaf litter and root decay, improving its structure and nutrient content.

Time: The duration over which soil formation occurs significantly impacts its development and characteristics. older soils have thicker profies and more complex structures

how does topography affect the soil formation/weathering

Topography significantly impacts soil formation and weathering by influencing water movement, erosion, and temperature, which in turn affects vegetation, soil development, and chemical reactions

how does “time factor” affect the formation of different horizons

Time is a crucial factor in soil horizon development, allowing for the accumulation of organic matter, the breakdown of parent material, and the translocation of materials within the soil profile

4 basic processes of soil formation

additions, losses, translocations, and transformations

know charactersitics of master soil horizons

are distinct layers within a soil profile, each with unique characteristics resulting from soil-forming processes

O - organic matter liked decaying leaves and humus

A - topsoil, ca mizture of mineral soils, organic matter, and humus. Dark in color

E - zone of eluviation where OM, clay, and other minearls have been leached. light in color

B - subsoil, materials leached from A and E accumulate. results in higher clay content and darker color than E. generally exhibits a higher bulk density

C - parent material with minimal alteration due to soil forming processes

R - bedrock

know types of soil erosion

geological erosion: s oil erosion that takes place naturally, without the influence of human activities

Accerelated erosion: the erosion processes speed up when we disturb the soil or the natural vegetation by grazing livestock and cutting forests for ag

water erosion: detachment, transport, deposition. raindrop slash effects: detach soil particles and send them in all directions

• sheet erosion - splashed soil is renoced nore lor less uniformily except for tiny columns

• rill erosion - numerous small channels only several centimeters in depth

• gully erosion - channels eventually remove the soil from this narrow area to considerable depth

wind erosion: about 28% of total soil deteriorations. removes most fertile part of topsoil

how much vegetated lan have we lost due to the land degradation

~5 billion ha (~45%)

mechanics of water erosion

deposition of eroded soil:

• deposition of eroded soil particles to the depression on a hillside of a slope and or to water channels and ocenas

transportation of soil

• raindrop splash effect: detach soil particles and send them in all directions

• role of running water: transportaiton of soil particles by runoff water

the universal soil loss equation (USLE)

R - rainfall erosivity: driving force for sheet and rill erosion

K - soil erodibility: a soil’s inherent susceptibility to erosion

L - slope length

S - slope gradients/steepness

C - cover and managment: types of vegetatove cover and cropping systems

P - erosion-control practices: tillage and contour strip-cropping, terrace systems, etc

Erosion control technologies

Conservation tillage

vegatative barrier & control of gully erosion

• a check dam: the construction of damns can reduce the flow of water to prevent further erosion

• narrow grass hedge: grass hedge can be effective in reducing runoff and erosion from soils

the great dust storm

1934, dust storm swept from great plains across eastern states

• experts estimate that 650000000 tons of topsoil have been blown away by this storm

• caused tremendous crop and livestock losses in kansas

what caused the dust storm

months of drought, the poor condition of soil from years of overproduction

how do you control wind erosion

To control wind erosion, the primary strategy is to reduce the wind's impact on the soil surface by either protecting it with vegetation or creating barriers

types of on-site and off-site damages of wind erosion

on-site: loss of surface horizon

• lowers CEC

• reduced nutrient supply

• less biological activity

off-side: sediment deposition inboth aquatic and terrestrial environments

• cause high turbidity

• raise the level of river due to sediment accumulation

• fill waterwats

• cover roads

what is rangeland in accelerated erosion

rangeland: grass cover generally protects soil surfaces

• poorly manage livestock grazing often leading to soil erosion

• cattle trails can channelize runoff water

what is forestland accelerated erosion

o horizons in undistrubuted forest protect the soil from the impact of rain droplets

• the construction of logging roads, timber-harvest operations

control of eccelerated erosions

• intensity of timber harvest - selective cutting and clear cutting on gentle slopes with stable soils

• tree removal methods could have impact on exposing soils

• scheduling of timber harvest: limiting entry into the forest by machineries could prevent the erosion

• design and managment of roads: placement of gravel on the road surfaces and lining the ditches with rocks

pedon

we characterize a soil individual in terms of imaginary 3D unit

polypedon

a soil unit in a alandscape usually consists of a group of very similar pedons

solum

upper and most weather part of soil (A, E, B)

soil profile

a vertical section of the soiil through all its horizons and extending into the parent materials

soil taxonomy

• moisture and temp

• color

• texture

• structure

• OM content

• clay, iron, and aluminium oxides, silicate clays, salts

• low activity clay (low CEC)

• pH

• % base saturation

Mollic (A)

thick, dark colored, high base saturation, strong structure

umbric(A)

same as mollic except low base saturation

ochric (A)

too light colored, low organic content or thin to be mollic; may be hard and massive when dry

melanic (A)

thick, black, high in organic matter common in volcanic ash soils

histic (O)

very hgih in organic content, wet during some parts of year

anthropic (A)

human modified mollic like horizon, high in available P

plaggen (A)

human made sodlike horizon created by years of manuring

Argillic (Bt)

silicate clay accumulation

Natric (Btn)

argillic, high in sodium, columnar or prismatic structure

spodic (Bh, Bs)

OM, Fe and Al ozides accumulation

cambic (Bw, Bg)

changed or altered by physical movement or by chemical reactions, generally nonilluvial

oxic (Bo)

highly weathered, primarily mixture of Fe, Al oxides and non-sticky type silicate clays

duripan (Bqm)

hardpan, strongly cemented my silica

fragipan (Bx)

brittle pan, usually loamy textured, dense

albic (E)

light colored, clay and Fe and Al oxides mostly removed

calcic (Bk)

accumulation of CaCO3 or CaCO3, MgCO3

gypsic (By)

accumulation of gypsum

kandic (Bt)

accumulation of low activity clays

salic (Bz)

accumulation of salts

Alfisols

distribution:

• dominate in ohio, indiana, and michigan, wisconsin, minnesota, penn, NY

• areas that recieve 20-50in precipitation under the forest veg

characteristics:

• >35% base saturated

• argillic horizon

• characterized by subsurface diagnostic horison in which silicate clay has accumulated by illuviation

Andisols (blacksoil)

distribution:

• found near volcano source or in areas downwind from volcanoes

• washington cascade in us, japan, new seasland, and chile

Characteristics:

• the principal soil-forming process has been the rapid weathering of volcanic ash to produce amorphous or poorlu crystallized silicate minerals such as allophane and the iron oxy-hydroxide

• some have a melanic epipedon a surgance diagnostic horizon that has a high organic matter content and dark color

Aridisols (dry)

distribution:

• southern cali, nevada, arizona, central NM, N mexico

characteristic:

• dry

• generally light in color and low in organic matter

• orchric epipedon, sometime argillic

• may have horizons that are irch in calciun carbonate, gypsum, soluble salts, or exchangebale sodium

Entisols

Distribution

• rocky mountains

• NW nebraska and SE coastal plain

• river valley, riverbanks, and deltas

characteristics

• With little or no morphological development other than an A horizon

• Weakly developed mineral soils without subsurface horizons (no diagnostic horizons). and most are basically unaltered from their parent material, which can be unconsolidated sediment or rock.

• Most have an ochric epipedon and a few have human-made anthropic or agric epipedons.

• Some have albic (light color eluvial) subsurface horizons

Gelisols (very cold)

distribution

• in northern russia. canada, and alaska

characteristics

• gelisols are young soils with little profile development

• the presence of a permafrost layer

• often contain cryoturbation

• some have developed in accumulations of mainly organic materials, making them histels

histosols (tissue)

distribution

• in wet areas of alaska, canada, finland, russia, iceland, ireland, and scotland

• in the everglades of florida and the bayous of NO

characteristics

• have undergone little profile development because of the anaerobic environment in which they form

• accumulate the partially decomposed organic parent material without permafrost

• due to high OM content, bulk desnity can be as low as 0.1 Mg/m3

cryoturbation

the physcial disturbance of soil materials caused by the formation of ice wedges and by the expansion and contraciton of water as it freezes and thaws

inceptisols (beginnning)

distribution

• in the mountains from southern ny through carolinas

  characteristics

• Few diagnostic features

• Often found on steep topography,

• resistant parent materials, low temperatures low precipitation.

• Often have only thin surface horizons (ochric or umbric epipedons).

• Slow development because of fast erosion/weathering before it develops.

• Weathering morphological features are being formed and destroyed continuously

  
  

mollisols (soft)

distribution:

• great plains of NA

• large grass land area

characteristics:

• dark soils, deep A horizon

• mollic epipedon

• >50% base sat

• some with argillic and natiric horizon

oxisols (oxide)

distribution:

• commonly occur in SA and africa

characteristics

• the most highly weathered soils

• form in hot climates with nearlt year round moist condiitons

• have either ochric or umbric epipedon

• have deep oxic horizon

4 important functions of soil

• medium for plant growth

• water storage supply and purificaiton

• modifier of the atmosphere

• a habitat for organisms that take part in decomp and habitat for other organisms

spodosols (wood ash)

distribution:

• northern europe and russia

• easternc anada

• NE us and michican

• alaska

Characteristic:

• occurunder coniferous forest in cool an dmoist areas

• the spodic horizon is usually thin, dark, illuvial horizon, typically underlies a light ash colored eluvial albic horizon

ultisols (last)

distribution:

• SE united states

• hawaii and in wester cali oregon

characteristics:

• highly leached, clay accumulation in a b horizon

• have an argillic and or kandic horizon

• have a relatively acidic b horizon with < 35% base sat

• some have horizons of iron rich mottled material called plinthite

soil

a mixture of minerals, OM, gases, liquids and myriad of micro and macro organisms that can support plant life. it is a naturla body that exists as part of the pedosphere

vertisols (turn)

distribution:

characteristics:

• 30% of sticky, shrink swelling clays

• form deep cracks when dried

• dark, even blackish in color

• unlike for most other soils, the om content is 1-6%

• develop from limestone or basalt

soil intersects with

• biosphere

• atmosphere

• hydrosphere

• lithosphere

what is the percent of mollisols in Illinois?

43%

Grassland Mollisols

soil ph ~5-6.5

microbiological activity

a thick A horizon

Woodland Alfisols

soil ph ~4 or lower

organic acid → an E horizon

less biological activity → a thin A, but an O

what percentage of Alfisols in Illinois?

45%

A horizon

the surface horizon of a mineral soil having maximum organic matter accumulation, maximum biological activity, and/or elevation of materials such as Fe and Al oxides and silicate clays

Abiotic

nonliving basic elements of the environment, such as rainfall, temp, wind, and minerals

accelerated erosione

erosion much more rapid than normal, natural, geological erosion; primarily as a result of the activities of humans or, in some cases, of animals

acid cations

cations, principally Al3+, Fe3+, and H+, that contribute to H+ ion activity either directly or through hydrolysis reactions with water

acid rain

atmospheric precipitation with pH values less than about 5.6, the acidity being due to inorganic acids (nitric and sulfuric) that are formed when oxides of nitrogen and sulfur are emitted into the atmosphere

acid saturation

the proportion or percentage of cation-exchange site occupied by acid cations

acid soil

a soil with a pH value <7.0. Usually applied to surface layer or root zone, but may be used to characterize and horizon

acid sulfate soils

soils that are potentially extremely acid (pH <3.5) because of the presence of large amounts of reduced forms of sulfur are exposed to oxygen when they are drained or excavated. A sulfuric horizon containing the yellow mineral jarosite is often present

acidity, active

the activity of hydrogen ions in the aqueous phase of a soil. it is measured and expressed as a pH value

acidity, residual

soil acidity that can be neutralized by lime or other alkaline materials and cannot be replaced by an unbuffered salt solution

acidity, salt replaceable

exchangeable hydrogen and aluminum that can be replaced from an acid soil by an unbuffered salt solution such as KCL or NaCl

acidity, total

the Toal acidity in a soil. it is approximated by the sum of the salt-replaceable acidity plus the residual acidity

Actinomycetes

a group of bacteria that form branched mycelia that are thinner, but somewhat similar in appearance to fungal hyphae. Includes many members of the order Actinomycetales

activated sludge

sludge that has been aerated and subjected to bacterial action

active layer

the upper portion of a Gelisol that is subject to freezing and thawing and is underlain by permafrost

active organic matter

a portion of the soil OM that is relatively easily metabolized by microorganisms and cycles with a half-life in the soil of a few days to a few years

adhesion

molecular attraction that holds the surfaces of two substances in contact

adsorption

the attraction of ions or compounds to the surface of a solid. Soil colloids adsorb large amounts of ions and water

adsorption complex

the groups of organic and inorganic substances in soil capable of adsorbing ions and molecules

aerate

to impregnate with gas, usually air

aeration, soil

the process by which air in the soil is replaced by air from the atmosphere. In a well-aerated soil, the soil air is similar in comp to the atmosphere above the soil. Poorly aerated soils usually contain more carbon dioxide and correspondingly less oxygen than the atmosphere above the soil

aerobic

1.) having molecular oxygen as a part of the environment.

2.) growing only in the presence of molecular oxygen, as aerobic organisms.

3.) occurring only in the presence of molecular oxygen

aerosol dust

a type of eolian material that is very fine (about 1 to 10 um) and may remain suspended in the air over distances of thousands of kilometers. Finer than most loessgga

aggregate (soil)

many soil particles held in a single mass or cluster, such as a clod, crumb, block, or prism

Argic horizon

a diagnostic subsurface horizon in which clay, silt, and humus derived from an overlying cultivated and fertilized layer have accumulated. Wormholes and illuvial clay, silt, and humus occupy at least 5% of the horizon by volume

agroforestry

any type of multiple cropping land use that entails complementary relations between trees and agricultural crops

agronomy

a specialization of agriculture concerned with the theory and practice of field-crop production and soil management. The scientific management of land

air porosity

the proportion of the bulk volume of soil that is filled with air at any given time or under a given condition, such as a specified moisture potential; usually the large pores

albic horizon

a diagnostic subsurface horizon from which clay and free iron oxides have been removed or in which the oxides have been segregated to the extent that the color of the horizon is determined primarily by the color of the primary sand and silt particles rather than any coatings on the particles

algal blooms

a population explosion of algae in surface waters such as lakes and streams, often resulting in high turbidity and green- or red-colored water, and commonly stimulated by nutrient enrichment with phosphorus and nitrogen

alkaline soil

any soil that has a pH >7.0 usually applied to the surface layer or root zone by may be used to characterize any horizon or a sample thereof.

allelochemical

an organic chemical by which one plants can influence another

allelopathy

the process by which one plant may affect other plants by biologically active chemicals introduced into the soil, either directly by leaching or exudation from the source plant, or as a result of the decay go the plant residue. the effects, though usually negative, may also be positive.