Soil Science Final
Dissolved organic matter is described as:
low molecular weight organic compounds that are readily soluble in water
Which of the following describes the fine earth fraction?
mineral particles less than 2 mm in diameter.
According to the lecture notes, soil is composed of:
mineral particles, organic matter and living biomass
What process releases soluble, inorganic nitrogen molecules as the result of the decomposition of nitrogen-containing organic substrates.
mineralization
When a soil is moist, the soil surface will be cooler than when the soil is dry because:
moist soil has a greater thermal conductivity and a greater heat capacity.
The soil surface beneath a plant canopy is cooler if the soil is moist than if the soil is very dry because:
moist soils support greater evapotranspiration rates than very dry soils.
When there are large quantities of basic cations and few acidic cations associated with the soil colloids the soil pH is seen to be:
neutral to alkaline
When there are large quantities of basic cations and few acidic cations associated with the soil colloids the soil pH is seen to be:
neutral to alkaline.
Most nitrogen leaching to groundwater is in the form of:
nitrate (NO3-).
Most plants obtain nitrogen from the soil by taking up:
nitrate (NO3-).
The transformation of ammonium (NH4+) into nitrate (NO3-) is called:
nitrification
The nutrient most often limiting the growth of phytoplankton and zooplankton in unpolluted ocean waters is:
nitrogen
The opposite process from nitrogen mineralization by the soil microflora is:
nitrogen immobilization by the soil microflora.
Which of the following nitrogen transformations in soil is not entirely or partially performed by soil microflora?
none of the other options listed (nitrification, denitrification, and N-mineralization)
Waterlogged soils when soil temperatures are also cold is:
not a serious problem for plants because O2 consumption rates are small.
In a collection of soils where time is the dominant soil forming factor
older soils will be deeper than younger soils.
In a collection of soils where time is the dominant soil forming factor:
older soils will be deeper than younger soils.
The great majority of nitrogen (95 to 98%) in soil-plant system can be found in the form of:
organic compounds
Thick O Horizons are commonly found in wet and/or cold soils because:
organic matter decomposition rates are slowed under these conditions.
Within the glaciated regions of Ohio are stream terraces whose soils were formed from sands and gravels deposited by rapidly flowing glacial meltwater. Which of the following is the parent material of these soils:
outwash
Which of the following soil organic matter components is the principal carbon and energy source for heterotrophic soil organisms?
particulate organic matter.
When comparing two soils, the one with the greater chemically reactivity would likely also have the larger:
passive SOC pool.
The pool within the soil carbon cycle that has the longest half-life is which of the following:
passive carbon pool.
The wetness state when a plant has done all the work it can do in removing water from the soil is called:
permanent wilting point
The wetness state when a plant has done all the work it can do in removing water from the soil is called:
permanent wilting point.
The higher plant symbiont benefits from the mycorrhizal relationship by principally obtaining which of the following from the fungus.
phosphorus
The nutrient most often limiting the growth of algae and cyanobacteria in unpolluted fresh water lakes is:
phosphorus
The nutrient most often limiting the growth of algae and cyanobacteria in unpolluted fresh water lakes is:
phosphorus.
The pores within a fine textured, clayey soil are
predominately micropores
The pores within a fine textured, clayey soil are:
predominately micropores.
Riparian buffer strips principally function in environmental protection to:
prevent the transport of nutrients and sediments from fields to streams.
Cation exchange in soils serves to:
retain nutrient cations within the rooting zone providing a continuous supply to the plant.
Which of the following is the correct ordering of organisms contribution to soil biomass (where > means greater than):
root biomass > microbial biomass > worm biomass
A landscaping contractor wants to change the texture of a clay loam soil to meet the specifications for a sandy loam soil. What would they likely add to the clay loam soil?
sand
The form of tillage used in row-crop agricultural production has little effect on the saturated hydraulic conductivity (Ks) value for which soil texture?
sand
Downslope lateral water flow in saturated soil below the water table is called:
seepage
A soil water fate contributing to baseflow of streams is:
seepage.
Downslope lateral water flow in saturated soil below the water table is called:
seepage.
Meso- and macrofauna contribute to organic matter decomposition primarily by:
shredding litter to enhance microbial activity
The weathering of silicate clays to form oxide clays is accompanied by the loss of:
silica
The soil components associated with P-fixation are, in order of degree of fixation:
silicate clays (least) << carbonate minerals < crystalline oxide clays < amorphous oxide clays (greatest).
Typically, the most erodible soil mineral particles are:
silt
Which of the following soil textures retains the greatest quantity of available water?
silt loam.
Typically, the most erodible soil mineral particles are:
silt.
Soil organic carbon can be classified into pools having differing half-lives. Which of the following pools is most closely associated with the soil's physical status (via aggregation)?
slow pool.
Using information presented in the table below, indicate which soil has the greatest potential fertility.
soil B (has all of the greatest numbers)
The association of mineral soil particles (sand, silt and clay) together with organic matter into larger sized units results in the formation of:
soil aggregates
Which statement below is not included in our definition of soil:
soil is the preferred depository of municipal and industrial waste.
Comparing soil microbes and forest litter:
soil microbes have a smaller C:N ratio than forest litter.
Water drainage in soil occurs between the wetness states of:
soil saturation and field capacity
Available phosphorus levels decline in lower pH, acidic soils because:
soluble phosphate (H2PO4-) reacts with Al3+ to form aluminum phosphate minerals.
The rate of plant litter decomposition depends on its biochemical form. Choose the appropriate order for rate of decomposition ranging from rapid to slow.
sugars, cellulose, lignins.
Which of the following supplies the greatest quantity of natural, nitrogen fixation?
symbiotic relations between bacteria and a host plant.
Exfoliation is caused by changes in:
temperature
The C:N ratio is:
the % total dry matter that is carbon divided by the % total dry matter that is nitrogen.
The active soil organic carbon pool is the most sensitive to cultivation because:
the active pool has a short half-life
The active soil organic carbon pool is the most sensitive to cultivation because:
the active pool has a short half-life.
As water drains from a soil:
the air-filled porosity value increases.
The heat capacity of a soil is:
the amount of heat energy required to increase the soil temperature by 1 degree Celsius.
The accumulation of fibrous, particulate organic matter as found in waterlogged peat bogs is the result of:
the compromised status of fungi under anaerobic conditions.
Mineral nitrogen that has become immobilized can be subsequently released by:
the death and decay of the early generation of microbes
Mineral nitrogen that has become immobilized can be subsequently released by:
the death and decay of the early generation of microbes.
The air-filled porosity of a soil can be calculated as:
the difference between the total porosity and wetness (water content) values at a specified soil depth.
The ratio between the amount of solute associated with soil colloids and the concentration of solute dissolved in the soil solution is called
the distribution coefficient
The ratio between the amount of solute associated with soil colloids and the concentration of solute dissolved in the soil solution is called:
the distribution coefficient.
According to the speaker, the better we understand the soil the more we understand the immense role microbes play in the continued capacity of a soil to function to its capabilities. Yet what do these soil microbes need most to perform their role?
the diverse habitat that a soil managed for health provides
According to the speaker, the better we understand the soil the more we understand the immense role microbes play in the continued capacity of a soil to function to its capabilities. Yet what do these soil microbes need most to perform their role?
the diverse habitat that a soil managed for health provides.
Which of the following groups of organisms are responsible for greatest magnitude of organic matter decomposition in soils, gaining nourishment from dead organisms or decaying organic substrates?
the heterotrophic microflora.
The greatest magnitude of cation exchange capacity (at neutral pH) is associated with which colloid class:
the humus colloids
The greatest magnitude of cation exchange capacity (at neutral pH) is associated with which colloid class:
the humus colloids.
In the 3-soils simulation shown in class, which of the following soils become driest at the surface due to water drainage below the rooting depth
the loamy sand soil.
In the 3-soils simulation shown in class, which of the following soils does not become saturated at the surface during the rain event?
the loamy sand soil.
The advantages of applying compost to the soil as compared with an equal quantity of fresh residues include:
the low C/N value of compost eliminates the nitrate depression period.
Which of the following colloids have the greatest proportion of positive, as compared to negative charges on their surface, and thus contribute to the anion exchange capacity of a soil?
the oxide clays
Runoff is:
the process that contributes stormflow to waterways.
The air-filled porosity of a soil is defined as:
the proportion of the total soil volume that is air-filled.
The soil cation exchange capacity (CEC) is defined as:
the quantity of exchangeable cations (expressed in moles of charge) for a given mass of dry soil.
Soil texture is:
the relative proportion of sand, silt and clay particles in a soil sample.
The risk of groundwater contamination by nitrate, NO3-, is particularly prevalent in the US Corn Belt because:
the small anion exchange capacities of these soils
The risk of groundwater contamination by nitrate, NO3-, is particularly prevalent in the US Corn Belt because:
the small anion exchange capacities of these soils.
What is the source of the direct uptake of plant nutrients by roots?
the soil solution
The author of the Quiz 6 article, notes that the presence of plants positively impact the abundance and diversity of microbes in soil because:
they provide a full menu of compounds exuded from roots and from decaying roots and leaves.
The nitrate losses from agricultural fields into streams that ultimately contribute to hypoxia in the Gulf of Mexico result from:
tile drain flow during the months of November through April.
The forest biome having the greatest Annelid biomass is the:
tropical forest
The undisturbed ecosystem having the greatest microbial biomass is:
tundra
As a simple demonstration of cation exchange:
two hydrogen ions in solution can exchange with one calcium ion on an exchange site.
Which of the following is not considered one of the four major factors influencing the mechanisms of soil formation?
valence state
Under which of the following conditions is a pollutant chemical prevented from leaching through the soil?
when in a colloid associated state
Which of the following places where potassium is found in soil makes this potassium unavailable to plants within a growing season:
within the crystalline structure of soil minerals.
Globally, the residence time of water in soil is approximately:
1 to 2 months
For adequate soil aeration, the air-filled porosity of a soil should not be below this value for extended periods of time:
10%.
The figure below was created from the 3-soils simulation results. It shows the infiltration rate of 3 soils all subjected to a rainfall at 12.7 mm/h from hours 1 to 8. Choose the best estimate for the percentage of the rainfall that infiltrated the sand textured soil.
100%
Globally, approximately what fraction of the historical soil carbon stock has been lost since the beginning of cultivation.
20 to 30%.
The figure below was created from the 3-soils simulation results. It shows the infiltration rate of 3 soils all subjected to a rainfall at 12.7 mm/h from hours 1 to 8. Choose the best estimate for the percentage of the rainfall that infiltrated the clay loam textured soil.
26%.
Choose the atmospheric conditions that support the greatest potential evapotranspiration (pET):
5% relative humidity during a windy, sunny day.
Globally, approximately what fraction of the historical soil carbon stock has been lost since the beginning of cultivation.
50 to 70%.
In the mid-latitudes, such as in Ohio, the soil temperature will remain constant throughout the year at which soil depth?
6 meters.
In what range of soil pH is phosphorus generally most available to plants?
6.0-7.0
Earthworm casts have properties different from the surrounding soil in which the worm is living, including:
A greater humus concentration.
A layer of soil, roughly parallel to the land surface that differs in properties from adjacent layers, below or above, is called:
A soil horizon
O2 and CO2 values in soil are dynamic, varying throughout the seasons:
Also, smaller O2 values correspond with larger CO2 values
O2 and CO2 values in soil are dynamic, varying throughout the seasons:
Also, smaller O2 values correspond with larger CO2 values.
In native biomes that have been undisturbed by tillage, organic carbon amounts are typically greater at the soil surface and decline with depth:
Also, this decline with depth is more gradual in prairie biomes.
For a silt loam soil which soil management practice will result in the larger saturated hydraulic conductivity (Ks) value?
An undisturbed native forest
In which of the following horizons has the process of illuviation most likely occurred?
B horizon
Evidence from a pasture ecosystem suggests that:
Below ground respiration rates from roots and food web members are comparable to that of above ground respiration rates from plant shoots and herbivores.
Soil macropores have two forms; biopores and inter-aggregate pores. Which one of the following statements is correct?
Both biopores and inter-aggregate pores function in the rapid conveyance of water and air long distances through soil.
In which of the following horizons has the process of illuviation most likely occurred?
E horizon.
A well aerated soil has O2 concentration values exceeding that of the above-ground atmosphere throughout a substantial soil depth.
False
Ammonia volatilization is a process by which much needed nitrogen is added to the pool of plant-available nitrogen in soil.
False
An indication that the plant is experiencing drought stress is when the actual ET exceeds the potential ET.
False
Anecic earthworm middens help protect the soil surface from crusting, runoff & erosion.
False
Even if managed properly, livestock serve no role in improving soil health.
False
For unimpeded root growth, soil O2 concentrations should be as large as, and soil CO2 concentrations should be as small as, the corresponding concentrations in the atmosphere.
False
Forests, due to their larger root biomass, contribute a greater carbon input into the soil than grasslands.
False
Most nitrogen leaching to groundwater is in the form of ammonium (NH4+).
False
Mycorrhizae do not normally kill their host plants, but merely reduce the efficiency of the plant root system.
False
Phosphorus fixation is due to the electrostatic attraction of phosphate anions to positively charged anion exchange sites on soil colloids.
False
Soils developed in loess, a parent material created by wind blown silts, are generally of little agricultural value.
False
Soils developed in wind-blown parent materials such as loess are generally of little agricultural value.
False
Soils having the greater available water capacities are only found in humid areas of the US.
False
Terra Preta describes the highly leached and infertile, Amazon Basin soil that was never influenced by human activity.
False
The magnitude of available water capacity is the same for all soils.
False
The order of strength of adsorption of ions by colloids and the relative amount of adsorbed cations when their solution concentrations are the same is Na > K > Mg > Ca > Al (where > means "is greater than").
False
When native prairie soils are brought under cultivation, the pool of soil organic carbon which disappears most quickly is the passive pool.
False
Of the total amount of potassium in soil, which fraction is the smallest.
K in solution
Of the total amount of potassium in soil, which fraction is the smallest.
K in solution.
Which of the following is a key soil health management principle?
Maximize the presence of living roots.
The phosphorus cycle is different from the nitrogen cycle principally because:
NO3- and NH4+ do not form mineral complexes like PO4-3 does.
If fallen tree leaves with a high C:N ratio (for example 80) are tilled into your garden soil, the micro-flora of the soil requires which of the following mineral nutrients in order to grow & decompose this organic substrate:
Nitrogen
If fallen tree leaves with a high C:N ratio (for example 80) are tilled into your garden soil, the micro-flora of the soil requires which of the following mineral nutrients in order to grow & decompose this organic substrate:
Nitrogen.
Organic carbon content is greatest in the
O horizon
Phosphorus as a plant nutrient presents fertility management issues (i.e. the phosphorus problem) because:
P content of native soils is relatively low due to phosphorus fixation.
In the un-glaciated regions of S.E. Ohio, where soils formed directly on the weathered in-place bedrock, the parent material of the soil is referred to as:
Residuum
A 5 C increase in soil temperature is likely to increase shoot growth of most plants more than a similar increase in air temperature.
True
A means to avoid non-point source phosphorus pollution in agricultural watersheds is to avoid applications that bring the available supply of P in soils to amounts higher that can be used by crop plants.
True
A pH probe when placed in a 1:1 water:soil suspension measures only the H+ ion concentration in the soil solution.
True
A soil with 80% base saturation would have a high percentage of the exchange sites occupied by basic cations, likely including the plant nutrient cations Ca2+, Mg2+ and K+.
True
An A horizon is more likely to be cultivated than a C horizon
True
Climate plays a role in plant-soil-water relations because, for example, a finer texture soil having proportionately more micropores will infiltrate a larger proportion of rainfall resulting from low intensity rains as compared with high intensity rains.
True
Compared to land that is not disturbed by tillage, moldboard plowed cropland usually loses much more particulate P than dissolved P.
True
Compared to the rest of the soil, the rhizosphere is considered a local hot-spot of organism activity due to the release by roots of exudates.
True
Evapotranspiration includes water losses both from the soil surface and from the leaves of plants.
True
For large areas of the US, there is a spatial correspondence between historical biomes and Soil Orders.
True
From the NE Ohio woodlot example, the passive SOC pool increases throughout the year, more rapidly with warmer soil temperatures and increased biological activity.
True
Fungal hyphae play an important role in stabilizing granular soil aggregates.
True
Fungi tend to better tolerate acidic soil conditions, such as found in forest biomes, than bacteria.
True
In acid soils the availability of some essential plant nutrient ions (eg. Ca, Mg, K) is decreased and the availability of some plant toxic ions (eg. Al) is increased.
True
In freshwater, P is the limiting nutrient that causes eutrophication while in ocean waters, N is the limiting nutrient that causes eutrophication.
True
In natural wetlands one would expect the redox potential (Eh) to be a comparably small value because of the low oxygen content.
True
Increasing amounts of organic matter can serve to increase the Available Water Capacity of a sandy textured soil and also increase the Saturated Hydraulic Conductivity of a clayey textured soils.
True
Mites and Collembola make up 80% of all soil arthropods.
True
Monthly streamflow is greatest during the winter months in a Mediterranean climate.
True
One reason why finer textured soils typically contain greater quantities of soil organic carbon is because clay - humus complexes protect organic matter from decomposition.
True
Phosphates bound to carbon in plant litter, roots, animal excreta and remains is the principal source of phosphorus input to the soil within natural, undisturbed ecosystems.
True
Potassium uptake in plants can exhibit luxury consumption, the uptake in excess of that needed for optimal growth or yield.
True
Residuum parent materials have formed in place and have not been transported from one area to another.
True
Soils of good tilth and high productivity are usually characterized by stable aggregation and a balanced percentage of macropores and micropores.
True
Soils with exceedingly small or exceedingly large percent base saturation, in their native states, are typically infertile.
True
Solutes in soil can exist in 2 possible states, either dissolved in the soil solution or associated with the soil colloids.
True
Some legume plants like clover enrich the soil with nitrogen, to the benefit of non-nitrogen fixing plants growing nearby.
True
Strongly weathered soils that contain mostly oxide clays have a relatively small cation exchange capacity and a relatively large anion exchange capacity.
True
Summer soil temperatures and growing vegetation result in a greater rate of O2 consumption and CO2 production than in winter with a bare soil.
True
The activity of anecic earthworms in corn-belt soils has some influence on hypoxia in the Gulf of Mexico.
True
The author of the quiz 4 article views soil health with its focus on building soil biology as the new agricultural revolution, supplanting the green revolution and its focus on chemicals and biotechnology.
True
The formation of unconsolidated material from rock relies on both physical disintegration and chemical alteration because physical exposure of new surfaces aids in the chemical alteration of minerals.
True
The greater percentage of gas exchange between the atmosphere and the soil occurs by diffusion of the concerned gases.
True
The heterotrophic microflora of the soil consumes POM by releasing extra-cellular enzymes and taking up some of the resultant, low molecular weight DOM.
True
The magnitude of available water for a given soil has a large effect on the local hydrologic cycle.
True
Unsaturated soils contain air-filled pores.
True
When mapped in 1912, peat deposits in Ohio were only found in the glaciated regions.
True
When precipitation and aET amounts are similar throughout the year, such as in Spencer, IA, and the soil has a large available water capacity; then soil wetness will vary slightly more or less than available water capacity value.
True
Within a semi-arid climate monthly soil wetness values are commonly less than the available water capacity of the soil.
True
Individual cations (e.g. Al3+, Ca2+, Mg2+, K+) vary with regard to their strength of attraction to cation exchange sites.
Yet, any one cation can replace any other cation by the rule of mass action.
You would be most likely to find P deficient plants in which location?
a corn field in tropical Africa
You would be most likely to find P deficient plants in which location?
a corn field in tropical Africa.
Traveling north to south across the heart-land of the US, the increasing mean annual temperature results in:
a decreasing quantity of soil organic carbon.
Very finely textured (i.e. clayey) soils have the following hydraulic properties:
a large available water capacity & a small hydraulic conductivity.
In the 3-soils simulation shown in class, the loam soil provided the greatest drought avoidance because:
a large proportion of the intense summer rainstorm infiltrated the soil.
Exfoliation is an example of:
a physical disintegration process.
Coarsely textured (i.e. sandy) soils have the following hydraulic properties:
a small available water capacity & a large hydraulic conductivity.
A layer of soil, roughly parallel to the land surface that differs in properties from adjacent layers, below or above, is called:
a soil horizon.
The soil moisture status that favors denitrification is:
a water saturated soil
Which one of the following terms represents a water loss from soil in the Water Balance Equation:
aET, actual evapotranspiration.
The processes involved with physical disentigration of rock into unconsolidated material includes:
abrasion
Among the microflora which group is responsible for the "earthy" smell of freshly plowed soil?
actinobacteria.
Which of the following is the correct order in the passage of carbon between soil carbon pools?
active SOC to slow SOC to passive SOC.
Which of the following soil carbon pools is most closely associated with soil health?
active pool
Which of the following soil carbon pools is most closely associated with soil health?
active pool.
The greatest quantity of O2 consumption in soil results from:
aerobic respiration
The greatest quantity of O2 consumption in soil results from:
aerobic respiration.
Drainage:
all of the other options given
Drainage:
all of the other options given. (generally ceases 2 to 3 days following a rainstorm, mostly removes water from the soil macropores, and reduces wetness in soil horizons positioned above the water table)
Prior to entering the soil surface, heat energy from solar radiation is diminished by which of the following processes?
all of the other options listed
The mineral materials from which soils are formed can be transported to their present locations by:
all of the other options listed
Why do you suppose that the boreal forest has a much smaller Annelid biomass in comparison to a tropical forest?
all of the other options listed
A cover crop is usually grown for the purpose of:
all of the other options listed.
Dissolved P loading in the Maumee River is increasing due to which of the following factors causing a build-up of P at the soil surface:
all of the other options listed.
Nitrogen is a component of which essential plant biomolecules.
all of the other options listed.
Plant root exudates:
all of the other options listed.
The potassium ion (K+) exists in soil as which of the following forms:
all of the other options listed.
Actual evapotranspiration (aET) is less than potential evapotranspiration (pET) when:
all of the other options listed. (a plant factor limits the rate of water flow to the leaf, a plant wilts due to drought stress, and a soil factor limits limits the rate of water flow to the leaf)
Why do you suppose that the boreal forest has a much smaller Annelid biomass in comparison to a tropical forest?
all of the other options listed. (boreal forest soils are commonly thin and acidic, the boreal forest is in a very cold climate, and the boreal forest consists of coniferous vegetation)
Dissolved within the soil solution are substances such as:
all of the other options listed. (cationic ions, anionic ions, gasses)
Factors that influence soil organic carbon levels in agricultural and natural ecosystems include:
all of the other options listed. (climate, soil texture, and vegetative biome)
Net radiation at the ground surface is partitioned into:
all of the other options listed. (latent heat, ground heat, and sensible heat)
The fate of phosphorus in soil is similar to the fate of nitrogen in the soil in which of the following ways?
all of the other options listed. (soluble P and N forms are subject to immobilization through their uptake by soil microflora, organic substrate decomposition mediates both N and P mineralization processes, and large quantities of P and N occur in humus, the passive form of organic matter that has a long half-life)
A cover crop is usually grown for the purpose of:
all other options listed. (contribute nutrients and organic matter to the soil, protect the soil surface, and capture nitrate left in the soil after the cropping season)
Which of the following parent materials is not associated with glacial activity?
alluvium
Which of the following soil parent materials would suggest that an area of soil is prone to flooding:
alluvium
Which of the following parent materials is not associated with glacial activity?
alluvium.
An acid soil is known to contain plant toxic elements in sufficient quantities to damage roots. Which of these elements is it most likely to be?
aluminum
An acid soil is known to contain plant toxic elements in sufficient quantities to damage roots. Which of these elements is it most likely to be?
aluminum.
The fungal symbiosis with herbaceous plant species wherein the fungus penetrates root cortical cells to form arbuscules; this fungus is referred to as:
an endomycorrhizal fungi.
Extreme environments such as acid mine drainage can support life in the form of:
archaea.
Fungi:
are aerobic heterotrophs.
Within plant tissue and soil biomass potassium exists solely as:
as part of the crystalline structure of feldspar.
In the winter, the coldest temperatures are observed at which soil depth.
at the soil surface
During months of the year when soil wetness greatly exceeds the available water capacity of the soil:
baseflow to streams is also large in comparison to other months of the year.
The class of soil structure that exists as cube-like units and is typically found in well-developed subsoil horizons is called:
blocky
Why do wet soils have a greater thermal conductivity than dry soils?
both minerals and water are good conductors so there are many paths heat can follow through the soil
The rate at which a mineral is chemically altered can depend on its composition. Therefore, all other factors being equal:
carbonates (as in CaCO3) weather faster than silicates (as in MgSiO4)
The rate at which a mineral is chemically altered can depend on its composition. Therefore, all other factors being equal:
carbonates (as in CaCO3) weather faster than silicates (as in MgSiO4).
The exchange of the adsorption state between a positively charged ion adsorbed to the colloid surface and one dissolved in the soil solution is the process of:
cation exchange
The exchange of the adsorption state between a positively charged ion adsorbed to the colloid surface and one dissolved in the soil solution is the process of:
cation exchange.
Choose the correct ordering (from fast to slow) for the rates of weathering of these common mineral classes.
chlorides > sulfates > carbonates > silicates > oxides
Choose the correct ordering (from fast to slow) for the rates of weathering of these common mineral classes.
chlorides > sulfates > carbonates > silicates > oxides.
Which individual textural class covers the largest area of the soil texture triangle?
clay
The weathering of sedimentary rock yields soil particles directly with little chemical alteration. Thus, mudstones weather to:
clay particles
In the unglaciated regions of S.E. Ohio, where rock fragments have tumbled to the valley floor, the parent material of the soil is referred to as:
colluvium
In the unglaciated regions of S.E. Ohio, where rock fragments have tumbled to the valley floor, the parent material of the soil is referred to as:
colluvium.
The mixed angular gravel, rock, and fine earth found at the foot of a slope is typical of what type of parent material?
colluvium.
Actinobacteria:
contribute to organic substrate decomposition by degrading chitin and cellulose.
One of the reasons why croplands have comparatively small microbial biomass values is that:
croplands do not commonly support perennial vegetation.
An example of a soil parent material formed "in place" is:
cumulous-organic.
The flow of carbon in soil:
cycles between living biomass and non-living organic matter.
For soil food web members the carbohydrate in aerobic respiration comes from:
decomposition of organic substrates mediated by the heterotrophic microflora.
The transformation of nitrate (NO3-) into nitrogen gas (N2) is called:
denitrification
Phosphorus can be found in 2 forms within surface waters: dissolved P and particulate P. Which of the following statements is correct.
dissolved P is highly bioavailable to algae.
Calcium, Ca2+, and magnesium, Mg2+, are essential plant nutrients and crop production in Iowa, for example:
does not require Ca2+ or Mg2+ fertilizer inputs
Calcium, Ca2+, and magnesium, Mg2+, are essential plant nutrients and crop production in Iowa, for example:
does not require Ca2+ or Mg2+ fertilizer inputs.
Which of the following actions would best assure good aeration in a soil?
drain excess water from the soil.
During months of the year when soil wetness is substantially less that the available water capacity of the soil
drought stress of vegetation is also evident.
Which of the following is the precipitation that infiltrates into the soil and penetrates deeply enough to aid in soil formation?
effective precipitation
The wetness state when gravity has done all the work it can in removing water from the soil is called:
field capacity
The available water capacity is the volume of water that can be retained by soil between the wetness states of:
field capacity and the wilting point
The soil wetness state when the force of gravity is insufficient to remove additional water from soil is called:
field capacity.
The natural grouping of individual clay colloids into a card-house arrangement is called a:
floc
The natural grouping of individual clay colloids into a card-house arrangement is called a:
floc.
One attribute of soil when serving as a natural resource it that it is:
fragile.
The loss of soil tilth is principally a response to:
frequent tillage associated with continuous row crop production
The loss of soil tilth is principally a response to:
frequent tillage associated with continuous row crop production.
Particulate organic matter in soil consists of:
freshly deposited or decaying organic tissues with an identifiable cellular structure
Which class of organisms contribute the greatest to the microbial biomass of the soil?
fungi
The exchange of gaseous molecules between the above-ground and soil atmospheres, from areas of greater concentration to areas of lesser concentration is specifically:
gas diffusion
The exchange of gaseous molecules between the above-ground and soil atmospheres, from areas of greater concentration to areas of lesser concentration is specifically:
gas diffusion.
Soil aeration is:
gas exchange between the soil and the atmosphere.
The principal process responsible for maintaining adequate O2 levels within the plant rooting zone of a soil is:
gaseous diffusion of O2.
Which type of soil structure is typically found in the topsoil (A) horizon of larger organic matter content soils?
granular
The dynamics of carbon flow through soil is illustrated by the:
half-lives of the active, slow and passive pools.
Soil pH:
has a large influence on the electrostatic charge of humus colloids.
An organic component of soil that is colloidal, gel-like and contains many carbon rings is:
humus
When fresh plant litter is added to soils, the priming effect may result in the decomposition of some:
humus.
A plant nutrient such as potassium, K+, that is retained on a cation exchange site can be displaced into the soil solution for subsequent root uptake by which ion that is released into the soil solution by the root itself:
hydrogen, H+
The various processes of chemical alteration of minerals includes:
hydrolysis.
Which of the following mechanisms of soil formation is considered to be a translocation process.
illuviation
In humid climates, the process whereby colloidal particles are entrained by percolating water and transported to a deeper depth is called:
illuviation, which over time results in a B horizon.
Which of the following mechanisms of soil formation is considered to be a translocation process
illuviation.
Arbuscules are biologic structures that are typically formed:
in root cortical cells by endomycorrhizal fungi.
The microflora of the soil:
includes bacteria, archaea, actinobacteria, fungi, and algae.
The active fraction of soil organic carbon largely accounts for which of the benefits of adding organic matter to soils?
increased biological activity
The active fraction of soil organic carbon largely accounts for which of the benefits of adding organic matter to soils?
increased biological activity.
Soil wetness at the wilting point:
increases uniformly with fineness of soil texture.
The rate or intensity of rainfall, such as given in units of in/h, influences the partitioning of water flow between:
infiltration and runoff
The saturated hydraulic conductivity (Ks) of a soil:
is a measure of the ability of a soil to transmit water when saturated
The saturated hydraulic conductivity (Ks) of a soil:
is a measure of the ability of a soil to transmit water when saturated.
A solute that has a large Kd value for a given soil:
is strongly associated with soil colloids and is prevented from leaching.
The magnitude of soil cation exchange capacity (CEC):
is unique to a given soil and also depends on the soil solution pH.
Fungi
lack cellular organelles such as mitochondria.
A soil having mostly macropores is expected to be well drained because of its:
large Ks and large drainable porosity values.
For a climate such as here in Ohio, a soil having a greater available water capacity would result in:
less seasonal streamflow and less seasonal drought stress
For a climate such as here in Ohio, a soil having a greater available water capacity would result in:
less seasonal streamflow and less seasonal drought stress.
Which of the following is not a mechanism of soil formation:
local topography
Which of the following is not a mechanism of soil formation:
local topography.
