Soils Exam 1
Geophagy
Deliberate eating the soil
A soil developed in transported parent materials will likely have properties related to the properties of the rock below the C horizon.
False
Alluvial parent materials are those that have been laid down in former lake bottoms.
False
Although subsoil is more difficult to obtain, it is generally equally as good as topsoil for landscaping purposes.
False
Except for some kinds of foods, modern industry has made human dependence on soils a thing of the past.
False
Glacial till is laid down by melt waters gushing out from the front of glaciers.
False
Soils developed in wind-blown parent materials such as loess are generally of little agricultural value.
False
Subsoil is typically equivalent to the O horizon.
False
The C horizons are generally more completely weathered than the other horizons.
False
The topmost horizon in most humid region forest soils is the A horizon.
False
Where organic matter constitutes only 1 or 2 percent of the soil by weight, it has only negligible influence on soil properties.
False
While many organisms depend on the soil for nutrients and water, only a few very specialized organisms live in the soil itself.
False
Horizon A
surface mineral horizon; lots of organic matter mixed with
Exfoliation is caused by changes in _________.
temperature
The amount of different sizes of mineral particles in a soil defines the soil ________.
texture
Horizon B
illuviation that has collected from the E horizon
Inceptisol
weakly developed, no clay accumulation
Which of the following is (are) essential plant nutrients?
Cu
layer of soil profile
Horizon
the relative proportions of the various soil separate in a soil
Soil Texture
Which of the following pH values represents the most acid condition?
1.0
A soil
3d natural body
In a load of 10 cubic meters of topsoil, approximately how many cubic meters of the volume would be solid material?
5
In a typical mineral soil in optimal condition for plant growth, approximately what percentage of the pore space would be filled with water and what percentage filled with air?
50% water and 50% air
Hydroxyl ion concentrations are greatest in a soil solution with a pH value of ______.
6.5
Which of the following pH values represents a neutral condition?
7.0
"Topsoil" is generally equivalent to which soil horizon?
A
In a given soil, the horizon with the highest organic matter content is generally the _____ horizon.
A
Discuss how a soil, a natural body, differs from soil, a material that is used in building of roadbed?
A soil is an organized, three dimensional body that is a component of a landscape. Mere soil is some material from such a body that can be moved around by a shovel or bulldozer
The water in the soil typically differs from pure water because the soil water ________.
A. contains organic compounds B. contains mineral nutrients C. is restrained in its flow by attraction to particle surfaces
Igneous rocks can best be characterized as:
A. rocks formed when molten magma solidifies
Use the key given in Figure 3.11 to determine the soil order of a soil with the following characteristics: a spodic horizon at 30 cm depth, permafrost at 80 cm depth. Explain your choice of soil order
Always begin at the top of the key. The presence of permafrost causes the soil to key out as a Gelisol. Only a "no" answer for the first two queries would allow the spodic horizon to come into play in keying out a Spodosol.
"Subsoil" is generally equivalent to which soil horizon?
B
In which of the following horizons has the process of illuviation most likely occurred?
B horizon
Increasing the organic matter content of a soil is likely to _____.
B. increase the soil's water holding capacity
Residual parent materials are best described as __________.
B. materials formed by weathering of rocks and minerals in place.
Compared to silt, clay-sized soil particles are characterized by ______.
C. greater attraction for water
organic and inorganic matter with very small particle size and a corresponding large surface area
Colloidal
the science that deals with influence of soils on living things particularly plants, including human use of land for plant growth.
Edaphology
Rearrange the following soil orders from the least to the most highly weathered: Oxisols, Alfisols, Mollisols, Entisols, and Inceptisols
Entisols (least); Inceptisols; Mollisols; Alfisols; Oxisols (most weathered)
Weathering of rocks usually is most intense in the center of a rock fragment, and gradually decreases toward the outside.
False
Andisol
Formed in volcanic material's has specific material properties related to density, phosphorus, and water holding
the more or less stable fraction of the soil organic matter remaining after the major portions of added plant and animal residues have been decomposed, usually dark in color.
Humus
water removed from first plant, hold water least tightly replaced with air
Macropore
Functions of soils in our ecosystems:
Medium for plant growth Regulator of water supplies Recycler of raw materials Atmosphere modifier Habitat for soil microorganisms Engineering medium
water held tightly, not always available to plant when here, generally filled with water rather than with air
Micropore
Which of the following is considered to be a plant macronutrient?
N, P, S, Ca
Are all elements contained in plants essential nutrients? Explain.
No, plants also take up elements which are not essential to the plant's growth. Examples are silica and sodium (not essential for some plants), selenium, vanadium, lead, etc. Some of these are nutrients for animals eating the plants, others (such as lead) are not, but are of concern because of their potential for animal toxicity
Organic matter accumulation is most pronounced in the ____.
O horizon
soils
One of the individual soil bodies
the unconsolidated and more or less chemically weathered mineral or organic material from which the solum of soils is developed by pedogenic processes
Parent Material
Compare the pedological and edaphological approaches to the study of soils. Which is more closely aligned with geology and which with ecology?
Pedologists study soils as natural bodies in the landscape without a particular land use in mind. Pedology is therefore closely related to surficial geology. The edapthological approach to soils aims at understanding the soil system as it relates to the suitability of the soil as a medium for plant growth. Edaphology is therefore a kind of ecology
the science that deals with formation morphology, and classification of soul bodies as landscape components.
Pedology
What does the soil provide for the plant?
Physical support Air Water Temperature moderation Protection from toxins
List the essential nutrient elements that plants derive mainly from the soil.
Plants derive these essential (or quasi-essential) elements mainly from the soil: N, P, K, S, Ca, Mg, Si, Na, Fe, Mn, B, Zn, Cu, Cl, Co, Mo, Ni
the unconsolidated mantle of weathered rock and soil material on the Earth's surface; loose earth materials above solid rock.
Regolith
the capacity of a soil to return in its original state after a disturbance
Resilience
a layer of soil, approximately parallel to the soil surface, differing in properties and characteristics from adjacent layers below or above it.
Soil Horizon
a vertical section of the soil through all its horizons and extending into the parent material.
Soil Profile
vertical section of the soil through all its horizons and extending into parent material
Soil Profile
the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation
Soil Quality
the combination or arrangement of primary soil particles into secondary soil particles into secondary soil particles, units, or peds
Soil Structure
Explain why Soil Taxonomy is said to be a hierarchical classification system.
Soil Taxonomy is hierarchical because at each level, several taxa are group together within a higher level category, e.g. several great groups are included in each suborder and several suborders, in turn, are included in each order.
the negative logarithm of the hydrogen ion activity of the soil
Soil pH
Soils in this order are commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates
Spodosols
Below the layer B horizon; deeper layer that stores water for later usage; not as good as topsoil for plant growth
Subsoil
The configuration of the land surface described in terms of elevation, slopes, and landscape position, the lay of the land
Topography
a horizon located; gets moved around with cultivation; fertile layer of soil; referred to as cultivated soil
Topsoil
Hydrolysis involves the splitting of water into its H+ and OH- components while hydration attaches intact water molecules to a compound.
True
Igneous rocks are formed when molten magma cools and solidifies.
True
Most of the water in our rivers and lakes has come in contact with and has been affected by soils.
True
Organic deposits are most common in areas where water flow over the soil surface is restricted.
True
Plants can be grown without any soil
True
Residual parent materials have formed in place and have not been transported from one area to another.
True
Secondary minerals are recrystallized products of the chemical breakdown and/or alteration of primary minerals.
True
Soil air usually has a higher carbon dioxide content than the air in the atmosphere.
True
The A horizons are more apt to be cultivated than the E horizons.
True
The O horizons of a soil are dominantly organic horizons occurring above mineral horizons.
True
The mineral particles in soil consist of sand, silt, and clay.
True
What is the principal soil property by which Ultisols differ from Alfisols? Inceptisols from Entisols?
Ultisols have a lower percentage base saturation (<35%) deep in the profile than do Alfisols. Inceptisols have some kind of easily developed B horizon while Entisols have no B horizon.
Of the five soil-forming factors discussed in Chapter 2 (parent material, climate, organisms, topography, and time), choose two that have had the dominant influence on developing soil properties characterizing each of the following soil orders: Vertisols, Mollisols, Spodosols, and Oxisols.
Vertisols: parent material, climate (dry season) Mollisols: organisms (grass vegetation), parent material (high calcium) Spodosols: climate (humid, high effective precipitation); parent material (sand or sand-forming) Oxisols: climate (hot, humid), time (very old)
Soil
a dynamic body on the surface of the earth in which plants grow and is comprised of air, water, minerals, and organic matter interacting with living organisms and is a product of climate and vegetation acting on a parent material in a specific location over time.
A soil pedon is ____
a three-dimensional unit that embodies the primary characteristics of an individual soil
As a society, is our reliance on soils likely to increase or decrease in the decades ahead? Explain.
a. Need to transform solar energy into food energy over huge areas of the Earth's surface. b. -Society's increased appreciation of and continued dependency on the services of natural soil-based ecosystems for water, wildlife, natural cycles and recreation. c. - Increasing replacement of petroleum by soil-grown plant products as feedstocks for chemical industry (e.g. soy bean based inks). . d. - Increasing replacement of finite fossil fuels with renewable plant-based biofuels (e.g. ethanol).
What are the six main roles of soil in an ecosystem? For each of these ecological roles, suggest one way in which interactions occur with another of the five roles.
a. Six soil roles or functions: i. (1) medium for plant growth; ii. (2) regulator of water supplies; iii. (3) recycler of nutrients and carbon; iv. (4) modifier of the atmosphere; v. (5) habitat for soil organisms; vi. (6) engineering medium. b. Examples of interactions between these roles: Plant cover (medium for plant growth) enhances infiltration of rainwater (regulator of water supplies); an abundance of soil organisms (habitat for soil organisms) enhances the release of nutrients (recycler of nutrients) by the decay of plant residues.
Describe four processes that commonly lead to degradation of soil quality.
a. Some soil degrading processes: erosion, salt accumulation (salinization), nutrient depletion, and chemical pollution.
Spodosol
acid, sandy, forest soils; highly leached; cold regions; coarse texture feel, highly acidic; not very put together
Utisol
argilic horizon, highly weathered and leached, developed under forests in humid topics and subtropics
Horizon R
bedrock; parent material
`the composite or generally prevailing weather conditions a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds throughout the year, averaged over a series ofyears
climate
The soil
collection of individually different soil bodies
Mollisol
dark, soft soils, associated with grasslands: worlds productive soils, great plains over the US is made up of
Verisol
dark, swelling, and cracking clay
Aridisol
dry soils; prominent in the west parts of the U.S. can be productive if managed and fertilized
the water that moves through the regolith and is largely available for plant growth
effective precipitation
Which of the categories in the Soil Taxonomy system indicates properties that have implications for root growth as well as for the construction of building foundations?
family
Which of the following categories of Soil Taxonomy provides the greatest specificity of soil properties?
family
Sedimentary Rock
form when weathering products released from older rocks collect under water as sediment and eventually reconsolidate into a new rock; most common
Igneous Rock
formed form molten magma
Metamorphic Rock
formed from other rocks by a process of change call metamorphism
The mixed angular gravel, rock, and soil found at the foot of a slope is typical of what type of parent material?
glacial
Gelisols
has permafors
The layers of contrasting material found when one digs a hole in the ground are called _______.
horizons
Horizon O
illuviation
Horizon C
minimally weathered; just becoming soil it lacks characteristics of other horizons
Alfisol
moderate leached; broad leafed forests and savannas
Oxisol
most highly weathered of the soil orders, rainforest, tropical areas like Hawaii
Histosol
organic soils without permafrost, peat moss
the smallest volume that can be called soil
pedon
two or more contigugous pedons all of which are within the defined limits if a single soil series, commonly referred to as a soil individual
polypedon
Most of the different nutrients essential for growth are supplied to plants directly from the ______.
rain water
Entisol
relatively undeveloped
Essential nutrients
required to finish life cycle
The lithosphere is made up of _________.
rock
A soil profile consists of _________.
soil feels
Nonessential nutrients
things that the plant takes up and doesn't need to grow.
Igneous, sedimentary, and metamorphic are three _________.
types of rock
Soil occupies the ______part of the regolith.
upper
Which of the following is not considered one of the five major factors influencing soil formation?
valence state
Horizon E
washed out, missing a lot of characteristics
all physical and chemical changes produced in rocks, at or near the earth's surface by atmospheric agents
weathering
Glacial till is a term used to describe parent materials that:
were transported by water gushing from glacial fronts.
