Soils Tracs Questions
The osmotic potential would likely be lowest in soils of which of the following orders
Aridsols
The process of aeorbic respiration is a significant source of which of the following gases
Carbon dioxide
Which of the following is considered to be a plant macronutrient
N
A well aerated soils is characterized by a relative abundance of
NO3- (nitrate) ions
Organic matter accumulation is most pronounced in the
O Horizon
Unsaturated water flow
Occurs on soils that are at field capacity
If you wanted to find a soil where physical weathering dominated over chemical breakdown you would be most apt to find in it
a desert region in Arizona
A soil with a bulk density equal to 0.35 Mg/m3 is most likely what type of soil
a peat soil
A soil pedon is
a three-dimensional unit that embodies the primary characteristics of an individual soil
In desert areas, the soil under scattered clumps of natural vegetation is usually depleted of nutrients compared to the unvegetated soil between clumps
True
Iron and aluminum hydrous oxides are characteristic of soils that are highly weathered chemically.
True
Nitrogen fertilization is a significant cause of acidity in many cultivated soils.
True
Nitrogen taken up by plants growing in a compost-treated soil is indistinguishable from the nitrogen taken up by plants growing in a fertilizer-treated soil.
True
Osmostic and metric potentials are commonly negative because the soil water has a lower energy level than that of pure water
True
Soil colloids are to small to be seen with an ordinary light microscope
True
The cation exchange capacity of a soil is determined primarily by the amount and kind of colloids in the soil and by the pH
True
The pollution of ground water is often increased by the presence of macropores in soils.
True
The soils of the world contain more carbon than all the world's vegetation and the entire atmosphere, combined.
True
The presence of rocks such as shale and sandstone indicate the existence of
ancient seas
The mixed angular gravel, rock and soil found at the foot of a slope is typical of what type of parent material
colluvial
Which type of structure is typically found in sodium-rich sub-surface horizons?
columnar
Hydrogen ions dominate the exchange complex of very acid soils (pH<5)
false
Compared to upland soils, wetland soils can be characterized by an abundance of
methane
Which of the following groups of organisms are responsible for greatest amount of organic matter decomposition in soils?
microflora
Humus is an important soil colloid. It differs from 2:1 type minerals in all but one of the following characteristics:
structural framework of the particles
In most soils the overall population (numbers) of microorganisms changes with time, generally following changes in the ________.
supply of decomposable organic matter
Char is made up of
pyrolized plant materials
The addition of large quantities of plant residues to the soil generally ________ the incidence and severity of soil-borne plant diseases.
reduces
Which of the following actions would best assure good aeration in a soil
remove excess water
Mycorrhizae improve the nutrition of many plants by
transporting phosphorus through the soil to the plant root
The amount of both P and K fertilizer applied to US farmland has increased dramatically since 1980 as American farmers attempt to maximize profits and meet record demand for foods
False
The cation capacity of soil humus is two to three times greater than that of an equal volume of high CEC silicate clays.
False
The cation exchange capacities of alkaline soils are commonly lower than those of comparable soils in humid regions
False
Conservation tillage is not practical in some areas of the northern part of the United States because the practice lowers the surface soil temperature in the spring of the year
True
Early snowfall that arrives before the cold winter weather has frozen the soil generally increases the penetration of water into the soil.
True
Approximately what percentage of the P in surface soils is typically found in organic forms
25 to 75%
In a load of 10 cubic meters of topsoil, approximately how many cubic meters are the volume would be solid material
5
Which of the following added to a soil would likely to result in the greatest level of soil organic matter after several years of decomposition
5 Mg of carbon in plant roots
In what ranges of soil pH is phosphorus generally most available to plants
5.5 to 7.0
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
Green plant residue such as grass clipping or a green manure crop generally have a water content of about ___ % by weight.
75
Two soils samples, A&B, at different soils 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. A= -5; B= +5 B. A= -5; B= -5 C. A= -20; B= -10 D. A= -30; B= -40 E. A= -100; B= -50
A = -30; B=-40
For which substance would the particle density equal the bulk density?
A quartz pebble
Disease suppressing soil often results from
Adding organic materials to the soil that stimulate diverse microorganisms
In which of the following horizons has the process of illuviation likely occurred
B Horizon
After dying to eliminate the water in plant litter, which two elements account for about 80% of the dry weight
C and O
Which of the following is (are) essential plant nutrients
Cu
In which soil order would recent alluvium most likely be a common parent material
Entisols
A pedon is a 3 dimensional field unit occupying about 1000 square meters (1 hectare) of land area
False
All but a few nematodes are pests, attacking either economic or wild plants.
False
Eutrophication is enhanced by the presence of pesticides in the water draining from agricultural soils
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
Humus has a much higher cation adsorption capacity at pH 5.5 than at pH 8.0.
False
Of the silicate clays, smectite has the least tendency to expand upon wetting and shrink upon drying.
False
On the Average, agricultural soils in the US are currently being depleted of their nitrogen supply
False
Research has shown that most herbicides and insecticides used in agriculture drastically reduce the number of living meso and microorganisms in soils for several years after application of these chemicals
False
The total number of microorganisms in a hectare of soil is far greater than the number of macroorganisms, but the total biomass of macroorganisms in 1 hectare is greater than the total biomass of microorganisms
False
While 2:1 type clays have significant internal surfaces, their external surfaces are generally much more extensive.
False
some 60 percent of the water that is actively involved in the hydrologic cycle worldwide is found in soil
False
A homeowner in New Mexico attempted to grow azaleas in a well drained soil (pH 7.5) but the plants were stunted and the leaves were yellow. What is the most likely cause of this constraint
Fe deficiency
Gypsum is the most widely used chemical for the reclamation of sodic soils. What characteristic likely accounts for this popularity?
Gypsum is abundant and low priced
If the soils are to be used for crop production, for which soil order would land drainage be most critical?
Hisotsols
Some irrigation systems have stimulated the formation of saline and saline-sonic soils. Which of the following contributes to this process
Inadequate drainage systems to remove soluble salts
Brown and red colors in subsurface horizons are caused by ________ in the soil.
Iron oxides
Which of the following statements is true
Lacustrine parent materials have been subject to weathering for shorter periods of time than residual parent materials nearby
If you want to reclaim a saline soil, which of the following practices would you most likely use
Leach the soil with water high in calcium and magnesium
An acid soils is known to contain toxic quantities of a certain plant nutrient. Which of these essential elements is it most likely to be?
Manganese
Most of the different nutrients essential for growth are supplied to plants directly from the
Soil Solution
Soils in this order are commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates
Spodosols
Fungal hyphae have an important influence on soil structure because they ________.
Stabilize macro aggregates
A soil profile consists of
The set of layers seen in a vertical cross section of a soil
Which of the following is not true with respect to the hydrologic cycle
There is a net migration of some 40,000 km3 of water in clouds from the land area to the ocean areas
A significant portion of the global production of methane comes from the activity from the activity of termites
True
Andisols are found mostly near recently active volcanoes.
True
Tillage when the soils to too wet is likely to increase the soil bulk density
True
Vertisols are characterized by high contents of swelling-type silicate clays.
True
leguminous forest trees, such as locust, enrich the soil in nitrogen, to the benefit of non-nitrogen fixing plants growing nearby
True
If you were looking for a soil with high cation exchange capacity and were not concerned with the soil's physical properties, which of the following would most likely fit your needs
Vertisol
Among the soils of which order would you most likely find the highest buffering capacities?
Vertisols
The sulfur dioxide in the atmosphere
all of the above a. comes from fires such as fossil fuel burning, volcanoes and forest fires b. can be an important source of sulfur nutrition for plants c. is a major contributor to "acid rain
Which of the following describes a soil likely to contain a significant content of low activity clays
an Ultisol in the Congo river basin in Africa
If a dry high in certain types of_____ is moistened, it is likely to swell up with enough force to crack pavements and building foundations
clay
Which of the following sources of water have the shortest average residence time
clouds
the water in the soil typically differs from pure water because the soil water
contains organic compounds contains mineral nutrients is restrained in its flow by attraction to particle surface (all of the above)
Which of the following plants would be most apt to tolerate high soil salinity
cotton
Which of the following processes are most apt to encourage good soil aeration
creation of more macropores
Soil detritivores feed principally on ________.
dead tissues
the bulk of gaseous interchange in soils takes place by
diffusion
The exchange complexes of strongly acid (pH 4.5) mineral soils are saturated mainly with ________
exchangeable Al3+ ions
Plant transpiration efficiency at a given location is markedly influenced by __________.
fertilization practices used and the plant species being grown
Which type of soil structure is typically found in surface soil (A horizons)?
granular
compared to silt, clay-sized soil particles are characterized by
greater attraction for water
A farmer started irrigating a soil some 10 yers ago but in recent years yields have declined and the soil physical condition has deteriorated. Which of the following most likely accounts for this situation
high SAR in the irrigation water
Which of the following characteristics of irrigation water is most apt to stimulate the formation of a sodic soil
high SAR values
Normal alkaline soils are not characterized by
high levels of exchangeable sodium
The total phosphorus lost from various watersheds is most closely correlated with ________
high soil erosion
Soils high in organic matter commonly hold more available water than comparable soils with lower organic matter levels. This is most likely die to what characteristics of the high O.M soils
higher field capacity
A wildlife biologist in South Africa notes that the soils on south-facing slopes are wetter and deeper than those on north-facing slopes, and therefore support more wildlife> What likely accounts for this difference
higher soil temperatures on the north slopes
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 data given
Increasing the organic matter content of a soil is likely to
increase the soils water holding capacity
Capillarity in soils
involves both adhesion and cohesion
Phosphorus availability in acid soils in constrained by the presence of significant quantities of reactive
iron
Poor plant growth in a well-drained irrigated soil in an arid region (pH=8.0) is most likely due to ________.
iron deficiency
Which of the following human actions is most apt to result in a long term increase in soil pH
irrigation with high sodium salt-containing waters
Biomass consists of
living organisms and cells
Which of the following is (are) major sources of the carbon dioxide now being added to the atmosphere in excess of the amount taken out by plants
loss of organic matter bring of fossil fuels destruction of natural forests (all of the above)
Which of the following is not a characteristic of soil colloids
low water holding capacity
Compared to the bulk soil in which the earthworms live, earthworm casts contain ________.
more of most plant-available nutrients
Under which of the following conditions would you favor a finely ground dolomitic limestone as your choice of a liming material
need to provide magnesium in addition to calcium
Which of the following is not a major factor in deterring the soil aeration status
nitrogen gas
Which of the following is a greenhouse gas contributed to the atmosphere by soils
nitrous oxides carbon dioxide methane (all of the above)
The matric potential of soil water is
not influenced appreciably by the force of gravity
The great majority of nitrogen(95% to 98%) in soils be found in the form of
organic compounds
The drainage of certain wetlands has resulted in extreme soil acidity. This is due primarily to which of the following processes that take place when the soil is drained?
oxidation of sulfur-bearing minerals that produces sulfuric acid
If you owned 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
Igneous rocks can best be characterized as
rocks formed when molten magma solidifies
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
A landscaping contractor wants to change the texture of a silt loam soil to meet the specifications for a loam. S/he would most likely do so by adding ______ to the soil and mixing it well.
sand
The most common form of on-site waster water treatment for homes not hooked up to sewer lines is the
septic tank and drain field
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
Which of the following categories of soil taxonomy provides the greatest specificity of soil particles
series
Texture describes the _____ of particles in a soil.
sizes
Which of the following pools contain the largest amount of the worlds carbon
soil
The amount of different sizes of mineral particles in a soil defines the soil
texture
Mechanical weathering processes result in
the disintegration of rocks due to different expansion of minerals
The swelling/shrinking tendency of some silicate clay minerals is due primarily to ________.
the movement of water molecules in and out of the interlayers of the crystal
The likelihood of polluting groundwater with pesticides and plant nutrients is enhanced by _______.
the presence of micropores in the soil
igneous, sedimentary, metamorphic are three
types of rocks
Which of the following is not considered one of the five major factors influencing soil formation
valence state
Which of the following best characterizes the field capacity of a soil
water content of a soil with water potential of about -10kpa