SSC 201 Exam 1

cold air damming

Cold, damp air is confined to the side of the mountains then spills over side

Lacustrine parent materials have been subject to weathering for shorter periods of time than residual parent materials nearby

T

residual parent materials have formed in place and have not been transported from one area to another

T

effective precipitation

The amount of precipitation that is actually flowing through regolith

lithification

The process that converts sediments into solid rock by compaction or cementation.

T or F: a 1:250,000 soil survey covers a larger area with less detail than a 1:12,000 soil survey

True

Select the appropriate soil order: Organic soils that are not frozen. a. Gelisols b. Mollisols c. Spodosols d. None of the above

None of the above

solum

O, A, E, B

Highly trained soil scientists generally map a soil landscape by sampling the soil in ___________.

bore holes in boundaries

vertisols

high in swelling clays, deep cracks when dry, vertical mixing

In which of the following epipedons is the organic matter level generally lowest?

ochric

Soil taxonomy listed from broadest to most specific?

order, suborder, great group, subgroup, family, series

what criteria are used to distinguish among soils in soil taxonomy?

organic matter, thickness, softness

Which of the following subsurface diagnostic horizons would you expect to find in a highly weathered soil of the humid tropics?

oxic

What is the regolith and how is it related to soil?

Solum plus parent material - the unconsolidated mantle of weathered rock and soil material on the earth's surface. -->loose earth materials above solid rock -->equivalent to soil in engineering -->varies in thickness from virtually non- existent to meters in other places -->regolith material is transported often many kilometers from the site of original formation and then deposited over the bedrock which it now covers

list the diagnostic subsurface horizons:

argillic, spodic, kandic, oxic, cambic

Which is one of the soil forming processes? Select one: a. Biotic Activity b. Transformations c. Time d. Climate

b

Saprolite

"rotten rock" that is easy to break, color and form of hardened bedrock

Bt

*clay accumulation* is indicated by finer soil textures and by clay cutans coating peds and lining pores

Bw

*development of color or structure* non illuvial "w" can = "weak"

Bh

*illuvial OM* accumulation

Bg

*mottling and gleying* of structurally altered material associated with periodic reduction

Ap

*plowed/disturbed* surface horizon (cultivation, pasture, forestry)

spodic

- Bh - an illuvial horizon characterized by the accumulation of colloidal OM, aluminum oxide and iron - commonly found in highly leached forest soils of cool humid climate, on sandy parent materials

organic epipedon

- Histic: a layer of organic soil that is naturally saturated with water (most OM) - Folistic: like the histic except it is not saturated with water for more than 30 days

mollisols

- dark soils of grasslands - high OM content - soft soils of grasslands - good physical condition - among the world's most productive (often used intensively for grain production)

A horizon

- dominated by mineral particles but darkened by the accumulation of organic matter - TOPSOIL - humus mixed with mineral particles - seeds germinate and roots grow here

aridisols

- dry soils - in natural state, the productivity is generally low - when irrigated these soils can be very productive

inceptisols

- few diagnostic features - process of soil formation begins in its early stages - weak B horizons (Bw) are typical

Which horizon would be the first to form in an Entisol? Select one: a. A b. Bt c. E d. B

A

alfisols

- have an Argillic subsurface horizon that is at least 35% saturated with basic cations - found under conditions of mild acid weathering - common under broad leafed forests and savannas

ultisols

- highly weathered soils developed under forests in the humid areas - more weathered and acidic than Alfisols - less weathered than Oxisols - not naturally as productive as Mollisols or Alfisols - low bases

oxic

- highly weathered, very high in Fe and Al oxides - only has 10% weatherable minerals in the sand, silt or clay sizes - these horizons are found mostly in humid tropical and subtropical regions

E horizon

- intensely weathered - eluviation, leached horizon so almost no clay or minerals - light in color - sand and silt Spodic?

B horizons

- less organic matter than the previous horizons nearer to the surface - silicate clays, iron and aluminum oxides, gypsum, or calcium carbonate - illuviation - SUBSOIL

entisols

- little if any profile development - lack a B horizon - parent material is the main determiner of potential productivity - ochric common

melanic epipedon

- mineral horizon that is very black in color due to its high OM content - density is very low - characteristic of soils developed from volcanic ash

C horizon

- parent material - slightly broken up bedrock - plant roots do not penetrate this layer - LEAST WEATHERED PART OF THE SOIL PROFILE

gelisols

- permanently frozen layers (permafrost and frost churning)

andisols

- recent volcanic ash deposits subjected to only mild weathering - dark in color, low in density, and quite easily managed

umbric epipedon

- same characteristics as the mollic except the percent base saturation is less than 50% due to leaching of basic cations (Ca, Mg & K). - develops in areas with higher rainfall than the mollic

mineral particles consist of ___. sizes?

- sand (2-.05mm) - silt (.05-.002mm) - clay (<.002mm)

spodosols

- sandy, quite acidic, have a Bh horizon - extremely acid soils in forested areas - found in moist (usually cold) regions - low bases - because of their high acidity and coarse texture, these soils are not naturally very fertile

factors that effect the rate of chemical weathering

- smaller particle sizes have greater surface area resulting in more rapid weathering - vegetation (CO2 evolution and carbonic acid formation, "Leakage of organic acids") - a decrease in temperature results in increased mechanical weathering - increasing water increases chemical weathering rates

Poor soil management can lead to _____ which can lead to _______ which leads to ____.

- soil erosion, salt accumulation, OM depletion, etc; - soil degradation - hunger and poverty

cambic

- the Bw horizon designation is used for this horizon - a slightly altered layer that has not undergone enough illuviation to become argillic

Soil texture

- the amount of different sizes of mineral particles in a soil defines the soil (sandy loam, silty clay, and clay loam, etc) - greatly affects water holding capacity and soil fertility

oxisols

- the most highly weathered of the soil orders - primary minerals have been essentially all destroyed - subsurface horizons dominated by oxides of iron and aluminum

What are the three general groups of minerals that tend to be found in well-weathered soils?

1) silicate clays, (2) very resistant end products, including iron and aluminum oxide clays, and (3) very resistant primary minerals, such as quartz

Organic matter makes up ____% soil dry weight

1-6

What are some of the benefits of organic matter in the soil?

1. binds mineral particles into a granular soil structure that is largely responsible for the loose, easily managed condition of productive soils 2. increases the amount of water a soil can hold and hte proportion of water available for plant growth 3. a major source of the plant nutrients phosphorus and sulfur and the primary source of nitrogen for most plants 4. the main food that supplies carbon and energy to soil organisms

Which six macronutrients are obtained primarily from the soil?

1. calcium 2. magnesium 3. nitrogen 4. potassium 5 phosphorous 6 sulfur

Why is water such an important component of the soil?

1. essential for the survival and growth of plants and other soil organsms 2. a major determinant of the productivity of terrestrial ecosystems, including agricultural systems 3. carries dissolved substances 4. not all soil water is available to plants

While the topsoil is where the majority of plant roots are located, why is an understanding of the subsoil and its properties important for proper soil management?

1. many soil properties are only discovered in deeper layers 2. plant growth problems can be caused by improper conditions in the B or C horizons 3. Subsoil is the zone of major accumulations of minerals and clays

What are the six "crucial ecological roles" of soil in our environment?

1. medium for plant growth 2. recycling system for nutrients and organic wastes 3. modifier of the atmosphere 4. habitat for soil organisms 5. engineering medium 6. system for water supply and purification

What special properties of soil water distinguish it from other forms of water?

1. never pure, contains many dissolved inorganic substances 2. resists changes in its composition even when compounds are added or removed from the soil, known as the buffering capacity of soil. 3. buffering capacity is dependent on many chemical and biological reactions

What essential needs for plant growth are supplied by the soil?

1. physical support 2. air 3. water 4. temperature moderation 5. protection from toxins (humus stains hands) 6. nutrient elements

What are the three mechanisms by which plant roots acquire nutrients from the soil system?

1. root interception 2. mass flow 3. diffusion

For every ____ degrees Celsius, biochemical activity doubles

10

one cubic meter of soil contains

100 earthworms 1000 insects 1M nematodes 1B fungi 1T bacteria

components of an "ideal soil"

50% solid (45% mineral and 5% organic material) and 50% pore space (1/2 air and 1/2 water)

Hydroxyl ion concentrations are greatest in a soil solution with a pH value of ________.

6.5

There are six soil master horizons, each designated by a different capital letter. The O horizon is a highly organic layer. The Rhorizon is the bedrock horizon. What are the other four master horizons, and what are the features that distinguish each?

A, B, C, and E -descriptions to follow in order from top to bottom

example of a least mature soil profile

A-C-R

example of a most mature soil profile

A-E-Bt-C

rank the following 4 moisture regimes from wettest to driest: ustic, aquic, udic, aridic

Aquic, udic, ustic, aridic

R horizon

BEDROCK

Select the appropriate horizon: Strong gleying indicating iron has been reduced and removed during soil formation. a. Ap b. Bg c. Bh d. Bt

Bg

Select the appropriate horizon designation: Illuvial accumulation of organic matter. a. Ap b. Bg c. Bh d. E

Bh

What three elements are NOT found in soil water

C, O, and H

Sedimentary rocks are classified into what three categories?

Clastic - broken pieces put together chemical - gypsum, halite biologic - coal

Calcium carbonate accumulation is more prominent in humid than in arid regions (t/f)

F

Limestone parent materials enhance the process of acidification.

F

Nutrient cycling in forested areas contributes little to soil formation

F

T or F: cold dry conditions result in deep well developed soils whereas wet and warm conditions result in shallow immature soils

F

Tropical forests protect the soil from excessive weathering (t/f)

F

Till and outwash are both examples of parent materials readily found in North Carolina

F - those are not parent material examples

crustal warping

Geologic forces, acting over time, can result in different parent materials being pushed into the zone of weathering

What are the differences among igneous, metamorphic, and sedimentary rocks?

Igneous rocks are formed when magma (or molten rocks) have cooled down and solidified. Sedimentary rocks are formed by the accumulation of other eroded substances, while Metamorphic rocks are formed when rocks melt and get pressurized deep in earth

What is pH and why is it considered a master variable in the soil environment?

Many chemical and biological reactions are dependent on the relative levels of hydrogen ions and hydroxyl ions in the soil solution, which are commonly determined by measuring the pH of the soil.

xeric

Mediterranean climate (moist, cool winters and dry, warm summers)

How do plants and animals contribute to physical weathering?

Plant roots sometimes enter cracks in rocks and pry them apart, resulting in some disintegration. Burrowing animals may also help disintegrate rock somewhat.

What country said soil has bodies?

Russia

How is the soil important in the life (and death) of many organisms?

Soil recycles plant and animal wastes and corpses, changing it to humus. Think of everything that has died since the earth began, were it not for soil we would be sitting on a pile of dead bodies right now. --->soil collects lots of carbon!

Particularly in terms of plant nutrient availability, why is the interaction of the soil solution and soil solids so important?

Soil solids, particularly the fine organic and inorganic colloidal particles (clay and humus), release nutrient elements to the soil solution from which they are taken up by plant roots.

A 1:1,000,000 soil survey has a larger scale than a 1:5000 soil survey (T/F)

True

If you wanted to find a soil where physical weathering dominated over chemical breakdown you would be most apt to find it in ________.

a desert region of Arizona

What is a soil individual? What is soil series?

a polypedon that is of sufficient size to be recognized as a landscape component - all of the soil individuals in the world that have in common a suite of soil profile properties and horizons that fall within a particular range are said to belong to the same soil series

A soil profile consists of _____. horizons in order

a set of layers in a vertical cross section' O, A, E, B, C, R

a subordinate designation of p indicates what?

a soil horizon with evidence of disturbance by agricultural activities

kandic

accumulation of Fe and Al oxides and low activity silicate clays, Kaolinite clays

Argillic horizons are characterized by ______.

accumulation of silicate clays (Bt)

organic matter is ______. clay and salts ______. and parent material ______.

added to surface translocated weathers into new soil

four general processes of soil genesis

additions, losses, transformations, and translocations

What are the four major components of soil?

air, water, mineral, organic

Organic parent materials are formed under the following conditions: Select one: a. Restricted aeration b. Permanently standing water c. Poorly drained marshes, bogs and swamps d. All of the above

all of the above

Floodplain (terraces and oxbows)

alluvial sediments carried and deposited terrace - old riverbanks, steps forming from sediment deposit oxbow - old stream cut off

A place where farms treat and store animal waste for fertilizer

anaerobic lagoons

Which of these diagnostic horizons develops as a direct result of eluviation and illuviation processes? Select one: a. Melanic b. Histic c. Ochric d. Argillic

argillic

deep rooted trees ____ in _____ soil and shallow rooted trees ___ in ____ soil

break/aerated, topple/saturated

Increase in rain increases _____ weathering while decrease in temperature increase _______ weathering.

chemical, mechanical

Secondary minerals are most prominent in the ________ fraction of soils.

clay

metamorphism

contact and regional, where minerals and crystals are rearranged in the rock

Glacial till parent materials

contain a heterogeneous mixture of mineral debris dropped by receding glaciers

the water in the soil typically differs from pure water because the soil water

contains organic compounds, is restrained by particles, contains mineral nutrients

silicates

crystalize from cooling magma

What is the difference between dark-colored and light-colored igneous rocks? What are examples of each? Which are more easily weathered?

dark-colored igneous rocks such as gabbro and basalt are more easily broken down than are granite, syenite, and other lighter-colored igneous rocks

Grass vegetation affects soil development in ways that will leave the soil _____ than soils under forest vegetation. Select one: a. lighter and less acid b. darker and less acid c. darker and more acid d. lighter and more acid

darker and less acid

what are the three basic tasks associated with mapping soils?

define each soil unit to be mapped compile information about the nature and classification of each soil delineate the boundaries where each soil unit occurs in the landscape

eolian (dune sands and loess)

dune sands - med to fine piled sand with short distance loess - fine sand, silt, and coarse clay moved far, in the Midwest region of the US

losses processes

erosion and leaching

ochric epipedon

fails to meet the definitions for any of the other epipedons (too light, too thin or too low in OM)

Ultisols are the result of physical weathering only. (T/F)

false

organic deposits are rarely found in areas of extreme wetness or extreme cold

false

The parent materials for most coastal plain soils are residual in nature. (t/f)

false - marine

foliated and non-foliated rocks

flattened or no obvious banding

Mineral composition and crystal/grain shapes can tell how a rock was ____.

formed

Lacustrine

former lake bottoms, layered because of different deposition events

crytoturbation

freezing causing slate to flake off slowly

In which of the following processes are space satellites used to collect geographic information about soils?

geo-positioning and multi-spectral imagery

Which mineral is most resistant to weathering under humid temperate conditions?

gibbsite

glacially transported material

glacial till - pushed in front of glacier glacial outwash - material transported and left as sediment when water melts

compared to silt, clay-sized soil particles are characterized by

greater attraction for water

information about condition at 2-4 meters deep in a soil is usually most helpful for understanding ______.

how best to design a building foundation

All chemical weathering reactions involve water in some way? In regards to the water, what is the difference between hydration and hydrolysis? Between these and dissolution?

hydrolysis reactions: water molecules split into their hydrogen and hydroxyl components, and the hydrogen often replaces a cation from the mineral structure. hydration: one mineral may be changed into another by the binding of intact water molecules Dissolution reactions occur when water hydrates cations and anions in a mineral until they become dissociated from each other and surrounded by water molecules

translocation processes

illuviation, eluviation, bioturbation, and cryoturbation

Synthesis

in-situ formation of secondary minerals and compounds from eluviated materials

what are diagnostic surface horizons? (epipedons)

includes upper part of the soil darkened by organic material, the upper eluvial horizons, or both. It may include part of the B horizon if the latter is significantly darkened by organic matter mollic, ubric, melanic, organic (histic), ochric

increasing organic matter will likely ______.

increase soil water holding capacity

Reduction Oxidation

ionic change to a lower valence in response to microbial activity in saturated conditions - exposure of mineral and organic materials to O2 which can lead to ionic change to a higher valence

More water or wet climates slow decomposition because ______

less oxygen present

Why is physical weathering more prevalent in dry, cool regions, while chemical weathering is more prevalent in wet, hot regions?

likes water and oxygen and biological agents- chemical

residual parent material

materials formed by weathering of rocks and minerals in place

exfoliation

method of physical (mechanical) weathering; process in which curved plates of rock are stripped from a larger rock mass

Frost Action

method of physical (mechanical) weathering; water freezes at night and expands because the solid occupies greater volume

Which of the following is not a secondary mineral? calcite, microcline, silicate clay, hematite, gypsum

microcline

What are the defining properties of a mollic epipedon?

mineral surface horizon noted for dark color associated with organic matter, thickness, and softness even when dry. high base saturation > 50%, - characteristic of soils developed under native prairies

rocks are made of

mixtures of minerals and other materials, broken rock, or even shells

delta deposits

mouth of a river into another body

how are soil series named?

named after a geographic feature near where they were first recognized

do all soils need to have a diagnostic subsurface?

no, since they may have not undergone very much soil development (unlike the epipedon)

histosols

peat or bog, high organic matter - most extensive in cool and cold climates, but are found all over the world

What are the two major weathering pathways? What is the primary difference between the two?

physical disintegration breaks down rock into smaller rocks and eventually into sand and silt particles that are commonly made up of individual minerals. Simultaneously, the minerals decompose chemically, releasing soluble materials and synthesizing new minerals, some of which are resistant end products.

Bioturbation

physical mixing of soil material by organisms (humans) or tree-throw

the transformation of gneiss into mica, quartz, and feldspar crystals is and example of ____.

physical weathering and disintegration

Organic matter greatly influences:

plant available water, porosity, microbiological properties, chemical properties

Why does clay have the most surface area?

plated and contains primary and secondary minerals, more negative charge resulting

What is the difference between primary minerals and secondary minerals?

primary mineral A mineral that has not been altered chemically since deposition and crystallization from molten lava. secondary mineral A mineral resulting from the decomposition of a primary mineral or from the reprecipitation of the products of decomposition of a primary mineral.

Why is a knowledge of soil properties critical when considering building on or in the soil?

provides support to built structures, poor soil provides a poor foundation.

Shrink-swell clay agriculture is dominated by _____ crop.

rice

Four natural environmental filters for water entering?

riparian buffers grassed waterways wetlands urban storm water management

Alluvial fans are usually characterized by ______ soils.

sandy and gravelly

Triasic Basin

sediments fell into huge canyon between chapel hill and NCSU, the clay here shrinks and swells so only huge corporations can afford to dig it up - creating research triangle

The map units on a detailed soil map in a county soil survey report are most likely to be labeled with names from which category of soil taxonomy?

series

Marine sediments form soils high in

silt and clay

atomosphere + pedosphere = lithosphere + pedosphere = biosphere + pedosphere = Hydrosphere + pedosphere =

soil air soil particles organic matter and biomass soil water

most of the different nutrients essential for growth are supplied to plants directly from the _____.

soil solution

regolith

solum + C

Most (usually 80% or more) of soil potassium and calcium can be found in the form of ______.

structural components of minerals

Human influence on formation of soils, such as many urban soils, is highlighted at what level in soil taxonomy?

subgroup

Which of the following categories of Soil Taxonomy provides the greatest specificity of soil properties? a. Great group b. Order c. Subgroup d. Suborder

subgroup

transformation processes

synthesis, weathering, reduction, oxidation (example: weathering of primary minerals to form secondary minerals)

Exfoliation is caused by changes in _____.

temperature

The topsoil is roughly equivalent to which master horizon?

the A horizon

Soil Structure

the combination or arrangement of primary soil particles into secondary particles, units, or peds. - These secondary units may be, but usually are not, arranged in the profile in such a manner as to give a distinctive characteristic pattern. - The secondary units are characterized and classified on the basis of size, shape, and degree of distinctness into classes, types, grades, respectively.

precipitates

the solid materials left behind after a liquid evaporates

O horizon

the top, organic layer of soil, made up mostly of leaf litter and humus, can be buried in layers below (does NOT illuviate)

Why are soil pores so important?

this is where air and water circulate, roots grow, and microscopic creatures live

what are the five major factors influencing soil formation?

time, climate, biota, topography, parent material

Increase of effective precipitation increases ___________

translocation (eluviation and illuviation)

A 1:5000 soil survey covers a smaller area with more detail than a 1:1,000,000 soil survey (T/F)

true

An argillic horizon is a diagnostic horizon characterized by the subsurface accumulation of silicate clays. (T/F)

true

Chemical weathering is accelerated by water, oxygen, and organic/inorganic acids moving down the regolith

true

Grasslands tend to have higher organic matter than forests (t/f)

true

T or F: Organic matter distribution in the profile is a significant criterion for differentiating epipedons.

true

The family category focuses on properties affecting plant roots and suitability for engineering uses of soils (T/F)

true

coniferous forests are found mostly in cool humid areas (t/f)

true

Worms, microorganisms, natural systems, mammals, and insects play a major role in ____ the soil.

turning

How do umbric, ochric, and histic epipedons each differ from the mollic epipedon?

umbric= percent base saturation is lower ochric= too thin, too light in color, too low in organic matter histic= thick layer of organic soil materials overlying a mineral soil

Soil occupies the ____ part of the regolith

upper

What is humus?

usually black or brown, a collection of very complex organic compounds that accumulate in soil because they are relatively resistant to decay, the colloidal fraction of soil organic matter

what is chemical weathering accelerated by?

water, oxygen, and organic acids moving down through the regolith

humus

well-decomposed organic matter, colloidal, relatively resistant to microbial attack

What conditions accumulate the most organic matter?

wet and cold

what types of information are contained in a modern county soil survey report?

yield potentials, suitability for different irrigation methods, drainage requirements