Final Exam Soil and Environment
The water potential at the leaf surface is expressed in kPA is most likely to be `
-10
At which of the following soil moisture potentials (expressed as kPa) is the waters energy level lowest?
-3100
At which of the following soil moisture potentials (expressed in kPa) is the soil held most tightly
-3100
Which of the following pH values represents an acidic conditions?
1.0
Which of the following pH values represent the most akaline condition
10.0
Hydrogen ion concentration are greatest in a soil solution with a pH value of
3
The ET from a pine forest was found to be 50 cm during the growing season. If the evaporation for the soil surface during the period of time was 5 cm, what is the level of loss from the leaf surface?
45 cm
"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
Which of the following locations in the United States would have the highest evaporation (E) from the soil surface in July?
A furrow-irrigated cotton field in Arizona
Two soil samples, A & B, at different soil moisture levels are placed in contact with each other. Water will more likely move from soil A to soil B if their water potentials, expressed in kPa, are:
A=-25 B=-35
Which of the following practices is(are) useful in stabilizing surface soil structure?
All the above (use of organic mulches, use of green manure crops, growing grass sod, and minimizing tillage)
which of the following describes a soil likely to contain a significant content of low activity clays?
An Alfisol in New York
The osmotic potential would likely be the lowest in soils of which of the following orders
Aridisols
In which of the following horizons has the process of illuviation most likely occurred?
B horizon
silicate clay accumulation is most common in the
B horizon
In the soils of which great group would most likley find wide surface cracks during periods of dry weather
Calaciusterts
The process of aerobic respiration is a significant source of which of the following gases
Carbon dioxide
Which of the following sources of water have the shortest average residence time?
Clouds
Which of the following processes are most apt to encourage good soil aeration?
Creation of more macropores
In which of the following soil orders would recent alluvium most likely be a common parent material?
Entisols
A friable soil is usually more likely to be indurated (hardened)
False
A soil of -0.02 kPa is more moist compared to soils with -0.0001 kPa soil water potential
False
Alluvial parent materials are those that have been laid down in former lake bottoms.
False
Although the total soil water content of a clay soil is about the same as a nearby well-structured silt loam, the clay will likely provide more available water to plants because of its higher volume of small pores
False
At the optimum water content in Proctor test the bulk density of a soil is at its lowest point
False
Because soil development is just beginning in Entisols, these soils are generally less variable in properties than are those in the Andisol or Ultisol orders.
False
COLE is measured of soil elasticity rather than expansiveness of soil
False
Eutrophication is enhanced by the presence of pesticides in the water draining from agricultural soils.
False
Evapotranspiration includes vapor losses from the soil surface and from the roots of plants
False
Filling the bottom half of a flower pot with gravel will greatly improve the aeration of the soil-mix in the top half.
False
For any soil, the bulk density is always lower than the particle density
False
For most soils, plowing and harrowing every year improves soil tilth in the long run.
False
Glacial till is laid down by melt waters gushing out from the front of glaciers
False
Gravitational water is water that is used by plants
False
Hysteresis is the phenomenon whereby a soil has a the same water content and water potential relationship when it is being dried as when it is being wetted
False
Hysteresis is the phenomenon whereby a soil has the same water content/potential relationship when it is being dried as when it is being wetted.
False
If the CO2 content of soil air is 3.5%, it is 10 times higher than that of the atmosphere.
False
Light colored surface soils are likely to be warmer than dark-colored surface soils if soil moisture and other conditions are the same
False
Polysaccharides produced by soils microbes and similar synthetic polymers applied to soils are largely responsible for the crusts that form when rain follows tillage
False
Roots of most plants have difficulty growing through soil if the bulk density is greater than 1.0 Mg/m^3
False
Soil of -1000 kPa has a higher potential than soil of -0.0001 kPa
False
Soils classified as Inceptisols have the least well developed profiles of those in any order in the Soil Taxonomy system.
False
Soils in the Oxisols order are deeply weathered and have deep subsurface horizons of silicon oxide
False
Spodosols are generally less acidic and less sandy than are Alfisols.
False
Subsoiling is a primitive deep tillage technique that results in extremely high subsoil bulk density.
False
The average residence of water in clouds over the ocean is about a year
False
The categories of Soil Taxonomy can be listed from the broadest (first) and most specific (last)as: order, suborder, great group,,suborder,series,family
False
The hydrogen end of a water molecule is attracted to positively charged cations such as Na+ and Ca2+
False
The particle density of water is 2.65g/cm^3and the density of soil is only 1.0g/cm^3, indicating that water is heavier than soil.
False
The percent of total pore space in a soil can be calculated if only the particle density and the organic matter content are known
False
The plasticity index is used to determine soil texture
False
The polarity of water molecule is due primarily to the fact that it contains two H atoms and only one O atom
False
The presence of iron in a mineral generally increases its resistance to chemical breakdown
False
The property of cohesion in water stems from the attraction of water molecules for soil solids
False
The specific heat of soil solids is significantly higher than that of water
False
The tenacity with which water is held in soils is directly related to the soil moisture content, the higher the moisture level the greater the attraction of the water to the soil.
False
The water potential in the soils is generally considered lower than in the atmosphere
False
When preparing a surface soil seedbed, the soil should generally be in the loosest, least dense soil condition in the row where the seed is placed
False
Wildfires in forested areas result in the formation of organic compounds that enhance the percolation of water through the soil.
False
You would be more apt to find a Gelisol in Iowa than in Alaska
False
If the soils are to be used for crop production, for which soil order would land drainage be most critical?
Histosols
Which of the following is (are) considered the necessary features for an area to be delineated as a wetland
Hydric soil
If the average transpiration (T) loss from leaf surfaces in a particular watershed is 10 mm/day, you expect the evaporation (E) from the soil surface to be ______.
Impossible to calculate from the given data
Which of the following soil temperature regimes would provide the warmest and least variable soil temperatures?
Isohyperthermic
The following are characteristics of a water molecule
It has a positive and negative side
Which of the following statements is correct?
Lacustrine parent materials have been subject to weathering for shorter periods of time than residual parent materials nearby
Soil colors are scientifically described by ________ color designations such as 10YR3/4.
Munsell
A well aerated soil is characterized by a relative abundance of
NH4+ ions
Which of the following will increase the evaporation (E) from the soil surface?
None of the above
organic matter accumulation is most pronounced in the
O horizon
In many soil profiles, the subsoil is high in clay, but is also quite permeable to percolating water. Why?
Prismatic structure may be well developed
Plant roots obtain access to soil water in which of the following ways?
Roots extend into moist soil area and water flows to the roots by capillarity
Which of the following is not a textural class name?
Sandy silt
Which of the following categories of Soil Taxonomy provides the greatest specificity of soil properties?
Series
Soils in this order are commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates
Spodosols
The difference between the liquid and plastic limits of soil is
The plasticity index
Entrophication
The presence of macro pores in the soil
Which of the following statements is not correct?
Tropical forests protect the soil from excessive weathering.
An abundance of macropores in soils helps assure an abundance of oxygen in the soil.
True
An aquic soil moisture regime connotes a higher degree of soil moisture saturation than an ustic one.
True
An argillic horizon is a diagnostic horizon characterized by the subsurface accumulation of silicate clays.
True
Andisols are found mostly near recently active volcanoes.
True
Atmospheric vapor pressure has little effect on the vapor losses from soil surfaces.
True
Capillary movement is made possible by the processes of cohesion and adhesion.
True
Chemical weathering is accelerated by water, oxygen, and organic and inorganic acids moving down through the regolith
True
Conservation tillage is not practical in some areas of Northern part of the USA because the practice lowers the surface soil temperature in the spring of the year
True
Drip irrigation is generally more efficient in the use of water than sprinkler irrigation especially for high valued crops
True
Drip irrigation is most likely used in the production of oranges and strawberry than in the production of corn
True
Evaporation from the soil surface (E) is determined to a large degree by soil surface wetness
True
Flocculation is the process by which certain chemicals in the soil stabilize large soil aggregates
True
Fungal hyphae play an important role in stabilizing surface soil aggregates.
True
Gypsum or nylon blocks are most useful in estimating the soil water content if the soil is quite dry.
True
Histisols generally have higher organic matter contents than Mollisols
True
Hydrolysis involves the splitting of water into its H+ and OH- components while hydration attaches intact water molecules to a compound.
True
In alkaline soils you would be concerned if the redox potential was low since it could mean a deficiency of some plant nutrients such as iron and maganese
True
Marine sediments are typical parent materials in coastal plain areas
True
Mollisols are characterized by a deep epipedon that is high in organic matter.
True
More than 98% of the earth's water does not take part in the annual cycling known as the hydrologic cycle.
True
Organic deposits are most common in areas where water flow over the soil surface is restricted
True
Osmotic and matric potentials are commonly negative because the soil water has a lower energy level than that of pure water
True
Oxisols are more highly weathered than are the soils of any other order.
True
Proper timing of tillage is generally more difficult for a clayey than a sandy soil.
True
Residual parent materials have formed in place and have not been transported from one area to another.
True
Respiration by plant and animal cells along with photosynthesis releases oxygen and consumes.
True
Soil and crop management generally has a great influence on evaporation from the soil surface (E) than on transpiration (T) from the leaf surface
True
Soil consistence changes with changes in soil water content.
True
Soil temperatures under an organic mulch will likely be lower than that of bare soils in the summer but higher than that of bare soils in the winter.
True
Soils of good tilth and high productivity are usually characterized by stable aggregation and a high percentage of macropores
True
The absorption of water on soil surfaces encourages capillarity
True
The alternative freezing and thawing of soils result in the upward heaving of plants and building foundations
True
The broadest category of classification in Soil Taxonomy specifies 12 soil orders, 11 of which are for mineral soils.
True
The drainage class of soils ( the degree to which the soil becomes water-saturated during the year) can be judged by the presence and location of gley in the soil profile
True
The effect of soil organic matter on the amount of water available to plants is due to organic matter influence on total soil porosity rather than to the water- supplying power of the soil organic matter
True
The family category focuses on properties affecting plant roots and suitability for engineering uses of soils
True
The great bulk of gaseous interchange between the soil pores and the atmosphere occurs by mass flow of the concerned gases.
True
The matric potential is due to the attraction of water molecules to soil surfaces
True
The most important management factors influencing soil aeration in well-drained soils are those that determine the volume of soil's macropores
True
The name of a subgroup indicates the order, suborder, and great group of which it is a member
True
The partial pressure of CO2 in the soil pores is higher than the partial pressure of this gas in the atmosphere
True
The percent nitrogen in the atmosphere is about 78% but carbon dioxide is only 0.035%
True
The plasticity index id the difference between the plastic limit and the liquid limit
True
The polarity of water helps account for the attraction of water molecules fro each other
True
The pollution of ground water is often increased by the presence of macro-pores in soils
True
The redox potential is a measure of the tendency of a substance to accept or donate electrons
True
The soil water potential is dependent upon the presence of salts and other solutes in the soil
True
The water potential at the field capacity for most soils is in the range of -10 to -30kPa
True
Tillage when the soil is too wet is likely to increase the soil bulk density
True
Vertisols are characterized by high contents of swelling-type silicate clays.
True
Water will move from one site in a soil with a water potential of -5kPa to an adjacent site with water potential of -40kPa
True
Water will move from one site in a soil with water potential of -50kPa to an adjacent site with a water potential of -140kPa
True
You would expect the installation of an effective tile drainage system in a naturally poorly drained soil in Iowa to increase soil temperature in the spring of the year
True
You would expect the installation of an effective tile drainage system in a naturally poorly drained soil of Louisiana to increase soil temperature in the spring of the year
True
Soils in which of the following soil suborders would most likely have a prominent E horizon under the A horizon?
Udalfs
Which of the following practices would encourage higher soil temperature in the spring in humid-temperate area?
Use a plastic mulch
You are seeking a soil with high clay content but one that is not sticky when wet nor hard and cloddy when dry. In which of the following suborders would you most likely find this soil?
Ustox
A soil with bulk density equal to 0.35Mg/m^3 is most likely what type of soil?
a peat soil
For which substance would the particle density equal the bulk density?
a quartz pebble
Argillic horizons are characterized by
accumulation of silicate clays
Which of the following diagnostic horizons would likely not restrict root growth in soils?
albic
Because of their greater surface are per unit of soil mass, silt loams soils generally have a greater capacity than loamy sand soils to ______.
all the above (absorb water, absorb gases, release nutrients by mineral weathering, and support bacterial growth)
Which soil moisture regime has the highest soil moisture levels?
aquic
A sticky, putty-like feel indicates a high percentage of which soil separate?
clay
Colloidal properties are exhibited by the ______ fraction of soils.
clay
If a dry soil high in certain types of _____ is moistened, it is likely to swell up with enough force to crack pavements and building foundations.
clay
Secondary minerals are most prominent in the ________ fraction of soils.
clay
Which type of structure is typically found in sodium-rich sub-surface horizons?
columnar
The bulk of gaseous interchange in soils takes place by
diffusion
The expression, P-ET-SS estimates the ________________ from a watershed
discharge volume
Which of the following irrigation systems produce the most biomass per unit of water applied
drip irrigation
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 type of soil structure is typically found in surface soil (A horizons)?
granular
Which of the following means of estimating soil water levels gives a direct measurement of the H2O content.
gravimetric determinations
In which of the following "forms" of soil water are pesticides, excess plant nutrients (excess fertilization), and waste chemical most apt to move through water
gravitational water
compared to silt, clay-sized soil particles are characterized by
greater attraction for water
In which of the following epipedons is the organic matter level generally lowest?
histic
Granite is an example of an?
igneous rock
Increasing the organic matter content of a soil is likely to ________.
increase the soils water holding capacity
Capillary in soils
involves both adhesion and cohesion
The element most often involved in oxidation reactions as minerals weather is
iron
Brown and red colors in subsurface horizons are caused by ________ in the soil.
iron oxides
Land drainage is beneficial because __________.
it increases the depth of root penetration in the soil
Using a textural triangle chart, it can be determined that a soil with 45% sand and 20% clay belongs to the ________ textural class.
loam
Dull gray colors are characterized by ______.
low chromas
Practices that add organic matter and reduce tillage can be expected to most significantly increase the ________ in a soil.
macro pores
Soil A has a redox potential of 400 mV, soil B -200 mV. Of the two soil, Soil A is more apt to be characterized by an abundance of _________.
molecular oxygen
Which of the following is not a major factor in determining the soil aeration status?
nitrogen gas
The matric potential of soil water is
not influenced appreciably by the force of gravity
Which of the following subsurface diagnostic horizons would you expect to find in a highly weathered soil of humid tropic?
oxic
Forest fires result in sufficiently high soil temperatures to cause the vaporization and movement of certain organic compounds in soils. The main effect of these compounds is to _______.
reduce water infiltration and percolation through the profile
If you own a dairy farm with poorly drained clay soils in a humid temperate region which of the following would be most satisfactory from the standpoint of soil aeration and temperature
ridge-till system
A landscaping contractor wants to change the texture of silt loam soils to meet the specifications for a loam soil. S/he could do so by adding to the soil and mixing it well
sand
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
The percentages of which soil components represent the minimum information
silt and sand
Texture describes the _____ of particles in a soil.
sizes
Fungal hyphae have an important influence on soil structure because they ________.
stabilize macro aggregates
Most (usually 80% or more) of soil potassium and calcium can be found in the form of ________.
structural components
Soil tilth refers to ______.
the physical suitability of a soil for plant growth
The redox potential is a measure of
the tendency of a substance to accept or donate electrons
If you dug a deep hole in your back yard and water started to seep into the hole it would fill the hole up to __________.
the water table
A soil has a thick black A horizon, a distinct B horizon, has reasonably stable soil structure, and was formed under grassland natural vegetation. In which suborder is it most likely classed?
udolls
Which of the following best characterizes the field capacity of a soil?
water content a soil with water potential of about -10kPa
Septic tanks for homes are usually built in
well draining soils
