soils

Parent material transported by ice is known as This parent material is found where glaciers have deposited material, such as in terminal moraines or lateral moraines.

glacial till

Soils are made up of more or less discrete layers called

horizons

Losses:

Through the movement of wind or water, or uptake by plants, soil particles (sand, silt, clay, and OM) or chemical compounds can be eroded, leached, or harvested from the soil, altering the chemical and physical makeup of the soil.

'Horizons' - revealed by differences in:

i. Color ii. Consistency: Texture, Structure iii. Location in the profile - depth from surface

The terms ------------------ classify parent material transported by lakes or the ocean. Again, this is water acting on parent material, and thus there is a high degree of particle sorting. ----------------- deposits sometimes have visible horizontal layers present, which indicate settling material deposition.

lacustrine and marine

Soil Horizon

: discrete layers of soil that are approximately parallel to the surface. Formed as a result of processes driven by the actions of the Soil Forming Factors.

weathering

Weathering is the process of disintegration of rock from physical, chemical, and biological stresses.

what does soil do to water ?

cleans the water by removing contaminants.

what soil condition would likely have the greatest water holding capacity?

Fine texture, high organic matter

With more water stable soil aggregates, it is expected that:

The rate of water infiltration and percolation will increase Soil crusting will be less; Resistance to the splash effect of raindrops will increase and soil erodibility will decrease; and Runoff will decrease, making more water available to the crop.

Water, being polar, is also attracted to itself

(cohesion

field capacity

- The soil is holding as much water as it can against the force of gravity. The very largest pores do not contain water. The corresponding potential is -33 kPa.

saturation

- The soil is said to be at saturation when all the soil pores are filled with water; that is, there is no air left in the soil. The corresponding potential is 0 kPa.

B horizon characteristics

-typically a mineral subsurface horizon and is a zone of accumulation, called illuviation. -The dominant processes in a B horizon are transformations and additions. -Materials that commonly accumulate are clay, soluble salts, and/or iron.

The bulk density of the soil is found by:

1. collecting a soil sample of known volume, 2. drying in an oven to 105º C, and 3. weighing it to find its oven dry mass.

Clay < 0.002

< 2

Sand < 2.00, > 0.050

< 2000, > 50

Silt < 0.050, > 0.002

< 50, > 2

C horizon characteristics

A C horizon consists of parent material, such as glacial till or lake sediments that have little to no alteration due to the soil forming processes. Low intensity processes, such as movement of soluble salts or oxidazation and reduction of iron may occur. There are no dominant processes in the C horizon; minimal additions and losses of highly soluble material (e.g., salts) may occur.

platy

Aggregates with short vertical dimension and long horizontal dimensions are called platy. Platy structures are common in the E horizon.

compound structure

All the structural types described above are called compound. Compound structure describes soils which have many well-formed aggregates. Soils without compound structure are said to have simple structure; that is, they have no aggregates, only a few aggregates, or many broken aggregates.

SOIL SOLID %

Bulkdensity/particle density x 100

soil structure types

Crumb A Granular A Blocky B Columnar B Platy E Massive C Single Grain C, (A in sandy soils) Puddled A

Cuboidal

Cuboidal aggregates have about equal horizontal and vertical dimensions. They include granular, crumb, and blocky types.

Types of soil structure can be divided into three categories

Cuboidal aggregates have about equal horizontal and vertical dimensions. They include granular, crumb, and blocky types. Prismatic aggregates have long vertical dimension and short horizontal dimensions. Prisms and columns are included in this category. Aggregates with short vertical dimension and long horizontal dimensions are called platy. Platy structures are common in the E horizon.

flat landscapes contribute to what

E horizons and poor drainage

What causes the difference between the surface horizon in the coniferous forest soil, (i.e., the black portion) versus grassland soil‏

Forest litter is acidic and more resistant to degradation by microorganisms

Soil water content may be expressed in two ways:

Gravimetric and Volumetric.

air dry

If oven dry soil is placed in air a small amount of water is taken up by the soil even though it seems dry. The water potential at air-dryness is about -3000 kPa.

A soil is developing in the Southeastern United States, on a geologically old, forested landscape, the temperatures are warm, and precipitation plentiful but the soil is well drained. Which of the following soil profile arrangements will best fit this scenario?

In this scenario, the older landscape with warm, moist conditions will encourage weathering of the soil minerals which will result in the formation and translocation of clays within the soil profile, resulting in a B horizon. The vegetation almost assuredly will provide an A horizon, and somewhere deep within the profile there will be parent material, the C horizon.

three common cementing agents

Iron and aluminum oxides serve as cementing agents in tropical soils. Also humus and clay

what does bright red or yellow soil mean ?

It is well drained and oxidized

soil temperature impacts

Life cycles of plants, insects, and wildlife are impacted and regulated by soil temperature

The color of a soil is described by soil scientists using the _____________________

Munsell Color System.

s the condition where water is under tension.

Negative potential

when the soil is in a dense massive condition that has no discernable aggregated structure or peds. This condition often results from the tillage (and compaction) of a finetextured soil when it is wet.

Puddled

Drainage class

Refers to the frequency and duration of wet periods under conditions similar to those under which the soil formed.

soil porosity

Soil Porosity % = 100% - Soil solids %

Soil aggregates

Soil aggregates are groups of soil particles that bind to each other more strongly than to adjacent particles. The space between the aggregates provide pore space for retention and exchange of air and water.

What is soil composed of ?

Soil is composed of a matrix of minerals, organic matter, air, and water.

E horizon

The E horizon appears lighter in color than an associated A horizon (above) or B horizon (below). An E horizon has a lower clay content than an underlying B horizon, and often has a lower clay content than an overlying A horizon, if an A is present. E horizons are more common in forested areas because forests are in regions with higher precipitation and forest litter is acidic. However, landscape hydrology, such as perched water tables, can result in the formation of an E horizon in the lower precipitation grasslands, as seen in the profile below. The dominant processes of an E horizon are losses.

O horizon characteristics

The dominant processes of the O horizon are additions of organic matter, and transformations from fibric to sapric.

bulk density

The mass of dry soil per unit of bulk volume (volume includes all soil pores). The 'bulk volume' is the volume of the soil at the time of sampling or measurement.

oven dry

The soil condition where all non-structural water has been removed. The Pw and Pv are zero at this point. The soil water potential is about -1,000,000 kPa.

wilting point

The soil does not contain enough water to support the growth of plants. On the average, plants wilt at this water content. The potential is -1500 kPa.

what three things are the soil generally heated by

The soil receives most of its heat from solar radiation with lesser amounts coming from warm rains and the decomposition of organic materials. Soils are also heated by conduction from below.

This soil is developing in an active floodplain in central China. The silty alluvial soils are somewhat poorly drained and the climate is on the cool side. The vegetative cover is grasses and other small forbs. Which of the following is the most likely horizon scenario?

The system described means that the soil is constantly being renewed by the silts that are deposited when the floodplain is flooded. This addition of material constantly resets the soil development clock. And, since this floodplain is active, it would be geologically young, so there has not been much opportunity for mineral weathering. The climate (cool, moist) also is not conducive for soil development in a short timeframe.

structure that has been ruined by destruction of the aggregates existing in the soil by excessive tillage or tillage when the soil conditions were not suitable.

This type is called puddled.

Soil Tilth

Tilth is the physical condition of the soil in relation to plant growth. It is described by the ease with which a soil can be tilled, it's fitness as a seed bed, it's impedance to plant seedling emergence and root penetration. A well aggregated soil, with good aeration provided by an abundance of macropores, water holding capability provided by micropores and adequate organic matter to maintain structure would be said to have good soil tilth.

Passive soil forming factors

Time Topography Parent Material

what does soil water content influence ?

Water content has a direct influence on plant growth, soil organism activities, soil temperature (heating and cooling), plant nutrient cycling, and leaching.

Very poorly drained

Water is removed from the soil so slowly that free water remains at or very near the ground surface during much of the growing season. The occurrence of internal free water is very shallow and persistent or permanent. Unless the soil is artificially drained, most mesophytic crops cannot be grown. The soils are commonly level or depressed and frequently ponded. If rainfall is high or nearly continuous, slope gradients may be greater.

Excessively drained

Water is removed very rapidly. The occurrence of internal free water commonly is very rare or very deep. The soils are commonly coarse-textured and have very high hydraulic conductivity or are very shallow

(adhesion).

Water, being polar, is attracted to the surfaces of the soil particles

Soils are __________ when air fills the soil pores.

aerobic

Prismatic

aggregates have long vertical dimension and short horizontal dimensions. Prisms and columns are included in this category.

Soils are__________ when soil pores are filled with water.

anaerobic

The very outer skin of Earth, the Soil, however has a ___________ much lower than Earth's overall average, and ranges from less than 1.0 g/cm3 for loamy soils with ample organic matter content, to over 2.0 g/cm3 for coarse textured soils that are tightly compacted.

bulk density

course soils have higher

bulk density

Inherent color

color of the rocks the soil formed from

Which of the following would cause an otherwise functional soil to lose its ability to perform its natural function in the ecosystem? A. mismanagement B. salinization C. overharvesting D. contamination E. none of the above

contamination

what type of soils do not form aggregates

course

physical property that compares the mass of a substance to its volume.

density

The main factors responsible for destruction of aggregates are

falling raindrops and tillage, or other soil disturbance

soil structure classes

fine, medium, course, very course

Water at a higher level is always at a higher potential than water at a lower level, because gravity pulls water downward. This component is called the _______________.

gravitational potential

what does soil textured determine

he rate of water and air entry into soil, water-storage capacity, and the ease with which roots move through the soil. It determines whether cation nutrients or pollutants are held in the soil or move downward.

gray soil comes from

humas

bulk density

indirect measure of the amount of pore space in the soil

grade,

is a measure of how well the aggregate is cemented together or, conversely, how easily it is broken down.

lack of moisture and high temperatures promote evaporation and thus CaCO3 (lime) accumulation near the surface and throughout the soil profile, making soil pH higher. what is the result of this ?

less humas

minerals

lithosphere

what does it mean when something is poorly drained

lots of moisture this adds to more humas

Density=

mass/volume

bulk density

mass/volume

If the soil material is fine, but there are no aggregates, and the soil is just a uniform mass, the structural type is ________

massive

cumulose

materials composed of mainly organic substances

What are two general practices which are key to preserving soil structure and maintaining soil aggregates?

minimize soil disturbance and maintain a soil surface cover

Soils that seasonally alternate between anaerobic and aerobic conditions have both gray and orange patches called ____________

mottles.

In addition, parent material formed from water flowing from glaciers is known as

outwash or glacial outwash.

the average density of the minerals themselves in the soil. It is a function of the mineral composition, not the arrangement of the particles

particle density

Particle density =

particle mass/particle volume

effects are not immediately observed

passive factors

A group of soil particles cemented together but separated from the rest of the soil is called

peds or aggregates

primary producers

plants

fine soils have higher

porosity

a condition where water pressure exists such as in soils covered with standing water.

positive potential

high albedo

reflects light (white)

osmotic potential.

salts in soils attract water (always negative)

Five water constants have been defined to help in our thinking about water potentials. These are:

saturation field capacity wilting point air dry oven dry

Soil structure 'Type' describes the ______________ of the soil aggregates.

shape

Medium and coarse sands naturally do not form aggregates. Their type is called

single grain

Which three of the following are considered 'Simple' soil structural types? Select 3 that apply.

single grain, massive, puddled

Soil structure 'Class' describes the ______________ of the soil aggregates.

size

something with high specific heat will warm up _______ and cool of ____________

slowly

. A wet soil warms and cools very _________ and a dry soil warms and cools __________

slowly - rapidly

the less the soil bulk density, the greater the .....

soil porosity.

The amount of sand, silt, and clay in a soil is measure of _______?

soil texture

The __________ of a substance is defined as the amount of heat it takes to raise one gram of that substance one degree C

specific heat

Soil structure 'Grade' describes the ______________ of the soil aggregates.

strength

low albedo

takes in heat (black)

Parent material transported from volcanic eruptions is called

tephra;

Subsoil:

that part of the soil profile below the plow or topsoil layer, generally considered to consist of B and C horizons.

soil structure-

the arrangement of soil particles

particle density

the density of the solid particles only

water

the hydrosphere

Capillarity

the movement of water in very fine tubes. If a fine glass tube stands in a pan of water, the water will rise up in the tube. The finer the tube, the higher the water will rise. The same process occurs in fine soil pores.

what does bright red and yellow soil mean

there is more oxygen in the soil to rust the iron within the soil

simple structure

they have no aggregates, only a few aggregates, or many broken aggregates

what has the opposite effect of mulch when regarding soil temperature

tillage mulch keeps water in therefor making the temperature changes act more slowly, whereas tillage dries out the soil making temperature changes more rapid

how deep down is soil ?

typically less than one yard

converted to lbs

volume x 62.4

The specific heat of most dry soils is about the same (0.25 cal/g. deg). However, the specific heat of water is 1.0 cal/g. deg, almost 4 times as high as that of soil. Therefore the rates of warming and cooling of soils are directly related to their ____________

water content.

matric potential

water is always attracted to soil particles (this potential is always negative)

Structural grades are classified as

weak moderate strong

loess

windblown sislt

volume

π x r(squared)x length

Seven classes of natural soil drainage are recognized—

—excessively drained, somewhat excessively drained, well drained, moderately well drained, somewhat poorly drained, poorly drained, and very poorly drained.

Parent material transported by flowing water (streams and rivers) is called

alluvium

consumers

animals

air

atmosphere

The soil seen here is very deep formed in alluvial and wind-blown deposits. The area between 30-60 cm (1-2 feet; measuring tape is in feet) has strong prismatic structure due to an accumulation over time of clay from overlying horizons. This accumulation of clay suggests what horizon type?

b

decomposers

bacteria, mold, fungi

is the weakening and subsequent disintegration of rock by physical forces.

Physical weathering

microbes that produce organic acids would be an example of

biological chemical

plant roots would be an example of

biological physical

Things that soil provides :

food, water, fiber, shelter

Hydration

the absorption of water into the mineral structure. A good example of hydration is the absorption of water by anhydrite, resulting in the formation of gypsum. Hydration expands volume and also results in rock deformation.

earth

the biosphere

Topsoil:

the layer of soil moved or disturbed by cultivation, usually consisting of any or all of the O, A, and E horizons.

soil

the predosphere

For plant growth, the__________ is the richest and most valuable part of the soil. __________ formation is a very slow process, which makes it a non-renewable (but re-usable) resource in terms of human lifespans. Keeping the soil in place while it is used for construction or crops is one of the greatest challenges faced by engineers and land managers.

topsoil

In an acidic, coarse-textured soil, in a location with a high rainfall, organic matter moves from the litter layer and is deposited on sand grains about 30 centimeters below the soil surface. This is an example of: ‏

translocation

why are we losing soil

we are trying to feed more and more people on fewer and fewer grounds causing the nutrients to deplenish and the soil to die

Biological weathering

weakening and subsequent disintegration of rock by plants, animals and microbes.

Four things that soil does for us

-Soil provides a physical matrix, chemical environment, and biological setting for water, nutrient, air, and heat exchange for living organisms. -Soil controls the distribution of rainfall or irrigation water to runoff, infiltration, storage, or deep drainage. Its regulation of water flow affects the movement of soluble materials, such as nitrate nitrogen or pesticides. -Soil regulates biological activity and molecular exchanges among solid, liquid, and gaseous phases. This affects nutrient cycling, plant growth, and decomposition of organic materials. -Soil acts as a filter to protect the quality of water, air, and other resources.-

Characteristics of A horizon

-mineral horizon -usually found at the top, howver it can be burred by flooding, volcanic eruptions, landslides, and dust deposition -dark color because they are rich in organic matter - The A horizon, over time, is also a zone of loss - clays and easily dissolved compounds being leached ouy -typically more course (less clay) than lower horizons -Additions and losses are the dominant processes of A horizons.

An "ecosystem" is ...

.a body of relationships that connect a community of living things with their environment and each other.

Humus:

1) organic materials in or on a soil that are in an advanced stage of decomposition. 2) A product of soil organisms that undergoes continuous breakdown, change, and synthesis. 3) previously living tissues that have been repeatedly consumed and/or digested by the variety of soil organisms, it coats soil particles and darkens their underlying colors due to its high percentage (>50%) of the element Carbon

how long does it take to develop an inch of soil

500 years

Which of the following soil properties have the LEAST influence on the ability of the soil to recycle dead plants, insects, and animals into the simple raw materials necessary for plant growth? A. soil textural class (% of sand, silt and clay) B. soil porosity and aeration C. tchemical composition of the material D. soil water content E. temperature

A

Soil Profile

A vertical cross-section of all the soil horizons at a particular location.

Soil is home for an enormous variety of living organisms (plants, insects, microorganisms, etc.). Which of the following soil properties will have the greatest influence on the ability of the soil to provide a suitable habitat for these organisms? A. textural class (% of sand, silt and clay) B. porosity (aeration) C. organic matter type and composition D. soil water content E. All of the above Check It

All of the above

Active soil forming factors

Climate- Organisms

is the weakening and subsequent disintegration of rock by chemical reactions.

Chemical weathering These reactions include oxidation, hydrolysis, and carbonation.

Soil Formation - Factors and Processes. What are the five factors that work in concert to produce a 'soil profile'?

Climate Organisms Relief Parent Material Time

Five soil forming factors

Climate, Organisms, tyopography, parent material, time

the removal of water from rock or mineral structures

Dehydration

The process by which water splits into hydrogen (H) and hydroxide (OH). Hydrogen and hydroxide replace elements on minerals. a chemical reaction caused by water. Water changes the chemical composition and size of minerals in rock, making them less resistant to weathering.

Hydrolysis

Master Horizons:

Layers of soil with distinctive characteristics and designated with the uppercase letters O, A, E, B, C, and R.

Additions

Materials added to the soil, such as decomposing vegetation and organisms (organic matter--OM), or new mineral materials deposited by wind or water.

Translocations:

Movement of soil constituents (organic or mineral) within the profile and/or between horizons. Over time, this process is one of the more visibly noticeable as alterations in color, texture, and structure become apparent.

Removal or exchange of electrons usually by combining with oxygen.

Oxidation Oxidation is the reaction of rock minerals with oxygen, thus changing the mineral composition of the rock. When minerals in rock oxidize, they become less resistant to weathering. Iron, a commonly known mineral, becomes red or rust colored when oxidized.

Carbonation

Reaction with carbonic acid. Carbonation is the process of rock minerals reacting with carbonic acid. Carbonic acid is formed when water combines with carbon dioxide. Carbonic acid dissolves or breaks down minerals in the rock.

What does soil do?

Soil provides mechanical support for living organisms and their structures. People and wildlife depend on this function.

What is soil quality ?

Soil quality is the fitness of a specific kind of soil to function within its surroundings, support plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation.

Soil is living resource that supports plant life

Soils is alive Dirt is dead

Soil Fertility

The ability of a soil to supply nutrients necessary for plant growth.

Soil Chemical Properties

The attributes of a soil described in chemical terms. Examples are mineralogy, acidity (pH), salinity, organic matter, and nutrient content.

Soil Productivity

The capacity of a soil, in its particular environment to produce plants under a defined management system

Soil Physical Properties

The characteristics, processes or reactions of a soil that are described by, or expressed in physical terms. Examples include bulk density, water holding capacity, porosity, and pore size distribution

Transformations:

The chemical weathering of sand and formation of clay minerals, transformation of coarse OM into decay resistant organic compounds (humus).

Soil Function

The various roles that soil performs, or the tasks that are placed upon soil, that underpin the concept of Soil Quality

the four general soil forming processes -

additions, losses, transformations, and translocations

This moist, dark slice of soil came from a pasture and shows the upper 30 cm (12 inches; measuring tape is in inches) of the soil profile. There is strong granular structure and lots of grass roots. There is even an earthworm (at yellow arrow). This layer of soil is mainly sand, silt, and clay, but there is also much more organic matter in this layer than the ones deeper in this profile. The likely soil horizon is:

a

The combination of sand silt and clay

a loam

Soil Quality

ability of a soil to function, within ecosystem boundaries to sustain biological productivity, maintain environmental quality, and promote plant and animal health.

influence over soil development can be directly observed.

active factors

The layer at 60-90 cm (2-3 feet; measuring tape is in feet) in this image is darker because it is wicking water up from below, much like a sponge set in a pan of water. The layers above it are drier. Wetting a soil up tends to make it darker. The texture of the indicated layer is sand and there is very little organic matter or soil activity (no clay accumulation, no leaching) going on. What is the likely horizon designation for this layer?

c

which soil properties will most influence soil fertility?

clay and organic matter content

Material transported due to gravity is known as --------. Gravity is a poor sorter of particles, and thus soils which develop at the base of mountains, for example, contain particles from clays through rocks, pebbles, and boulders.

colluvium

Soil Texture:

describes the content of sand, silt, and clay particles in a soil. Can be described as fine - clayey, medium - loamy, or coarse - sandy

Soil Structure:

describes the shape, size, and strength of aggregated soil particles.

provisioning ecosystem services

ecosystem services that come from soil and provide for us (place to grow food, used to build etc)

regulating ecosystem services

ecosystem services that help regulate the environment (soil cleans water through physical filtration system, and stores carbon)

One example of microbial activity is _______; _________ is fungi and algae, living together in a symbiotic relationship. Fungi release chemicals that break down rock minerals; the minerals thus released from rock are consumed by the algae. As this process continues, holes and gaps continue to develop on the rock, exposing the rock further to physical and chemical weathering.

lichen

Parent material transported by wind has many names. The most common names are --------

loess or aeolian.

Calcium carbonate (CaCO3) in a soil layer dissolves in water that is percolating through the soil. The water flows deeper into groundwater and eventually enters a stream. This is an example of: A. Addition B. Loss C. Transformation D. Translocation

loss

Soils perform five key functions in the global ecosystem. Soil serves as a:

medium for plant growth, regulator of water supplies, recycler of raw materials, habitat for soil organisms, and landscaping and engineering medium.

Which of the following categories of land degradation would be most likely to leave the soil in a condition making it vulnerable to erosion? A. mismanagement B. salinization C. overharvesting D. contamination E. none of the above Check It

mismanagement

Question 10: This slice of soil was pulled from a wetland. The first 10 cm (4 inches; in the yellow box) is all decomposing organic matter. The dark gray layer underneath is mostly mineral with some organic matter mixed in. The horizon indicated in the yellow box is a(n) ____ horizon.

o

Which of the following results in a gradual loss of natural soil fertility? A. mismanagement B. salinization C. overharvesting D. contamination E. none of the above Check It

overharvesting

Finally, parent material weathered in place is called either --------------------

residual or residuum.

Irrigation of soils in an arid environment can contribute to which of the following? A. mismanagement B. salinization C. overharvesting D. contamination E. none of the above

salinization

Subordinate horizons

soil layers designated by lowercase letters to indicate specific characteristics of a master horizon.

the combination of all the soil layers

soil profile