soil science final
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
In a load of 10 cubic meters of topsoil, approximately how many cubic meters of the volume would be solid material?
.5
how to find EP
1-(PB/particle density constant 2.65)
Secondary minerals are most prominent in the fraction of soils.
clay
Respiration by plant and animal cells along with photosynthesis releases oxygen and consumes carbon dioxide t/f
false
Routine soil testing on a regular basis allows landowners to monitor most changes in soil quality. T/F
false
An acid soil is known to contain toxic quantities of a certain plant nutrient. Which of these essential elements is it most likely to be?
manganese
To be classified as a conservation tillage practice, a system must leave at least what portion of the soil surface covered with plant residues?
30%
Wind erosion accounts for about what percent of the total soil erosion losses in the United States?
35%
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 50% air
Which cation would you expect to be mostly tightly held in a soil at pH 4.5?
Al3+
"Subsoil" is generally equivalent to which soil horizon?
B
Silicate clay accumulation is most common in the ____ horizon.
B
The total number of microorganisms in a hectare of soil is far greater than the number of macroorganisms, but the reverse is true for biomass of the two groups. T/F
False
Regarding the topics Dr. Elaine Ingham talks about in the assigned video ("Two Examples of Overcoming Problems that Lead to Poor Production"), which one of the following statements is not true?
Microorganisms in soil do not pull salts out of the soil.
In Dr. Elaine Ingham's talk on "Two Examples of Problems that Lead to Poor Production" (see the link on TRACS/Resources), she tells the story of a dairy farm in Camperdown, Australia that was having problems with an accumulation of manure in pits and poor pasture plant production. Which statement below is not true of this case study?
Nitrogen and phosphate fertilizers were applied to the pastures, along with the composted manure, to increase the growth of the grasses and legumes, such that the dairy herds became healthier and didn't rip out the roots of the plants they ate.
On which of the land use capability classes is suggested use restricted to non-production purposes, only wildlife and recreational purposes being appropriate?
VIII
A soil with a bulk density equal to 0.35 Mg/m3 is most likely what type of soil?
a peat soil
For which substance would the particle density equal the bulk density?
a quartz pebble
A soil pedon is ____.
a three-dimensional unit that embodies the primary characteristics of an individual soil
Members of this (these) microbial group(s) are responsible for a major proportion of the nitrogen fixed globally in symbiosis with higher plants.
actinomycetes and bacteria
Disease suppressive soil often results from _____.
adding organic materials to the soil that stimulate diverse microorganisms
The following two questions are based on the Glen Rabenberg's podcast (see TRACS/Resources for the link). Glen Rabenberg, along with colleagues, did a multipart study on calcium. After spraying deionized calcium on different types of soil and different crops (e.g. corn, grains, alfalfa hay, grass hay), the crops were fed to different species of livestock (e.g. steers, hogs, laying hens, broilers). What did they find?
all of the above
Organisms which use carbon dioxide or carbonates for their carbon source and either sunlight or inorganic chemicals for their energy source are called ____.
autotrophs
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
The mixed angular gravel, rock, and soil found at the foot of a slope is typical of what type of parent material?
colluvial
In nature, beneficial mycorrhizae form with the roots of _____.
coniferous trees, grasses, legumes, and broad leaf trees
The water in the soil typically differs from pure water because the soil water ________.
contains organic compounds, mineral nutrients, and is restrained in its flow by attraction to particle surfaces
Which of the following processes are most apt to encourage good soil aeration?
creation of more macropores
Soil detritivores feed principally on ___.
dead tissues
If you wanted to find a soil where physical weathering dominated over chemical breakdown you would be most apt to find it in ______.
desert region in Arizona
how to find PB
dry soil/ (3.14)(1/2 volume diameter)^2(height)
In which soil orders would recent alluvium most likely be a common parent material?
entisols
The exchange complexes of strongly acid (pH 4.5) mineral soils are saturated mainly with _____.
exchangeable Al3+ ions
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. t/f
false
Eutrophication is enhanced by the presence of pesticides in the water draining from agricultural soils. t/f
false
Filling the bottom half of a flower pot with gravel will greatly improve the aeration of the soil-mix in the top half. t/f
false
Fungi are much more sensitive to strong acid conditions than are bacteria or actinomycetes. t/f
false
Hydraulic redistribution or hydraulic lift dries out shallower soils during dry periods, allowing trees to take advantage of water deeper in the soil profiles. t/f
false
Hydrogen ions dominate the exchange complex of very acid soils (pH<5). t/f
false
Kaolinite is most prevalent in soils developed from volcanic ejecta (Andisols). t/f
false
Living organisms affect soil formation primarily by their constraining the level of oxygen in the soil. t/f
false
Of the silicate clays, smectite has the least tendency to expand upon wetting and shrink upon drying. t/f
false
Recent research with annual crops such as wheat, sunflower and sorghum in the Great Plains region suggests that, compared to continuous cropping, soil quality, crop productivity and farm profitability are likely to be greater when crops are grown in a field only every second year with the soil kept free of weeds in the non-crop year by repeated cultivation of herbicide application. t/f
false
Soils developed in wind-blown parent materials such as loess are generally of little agricultural value. t/f
false
The acidity of "acid rain" can be traced to the reaction of CO2 in the atmosphere forming carbonic acid (H2CO3). t/f
false
The cost of fertilizer is the main consideration of nutrient management for most ornamental landscaping applications. T/F
false
The drainage of some coastal wetland soils results in high pH due to underlying lime deposits. t/f
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. t/f
false
The total global soil lost through erosion is generally greater from gully erosion than from sheet erosion. t/f
false
Yields of row crops on poorly drained soils are generally somewhat higher with no-tillage systems than with conventional tillage systems. t/f
false
Which type of soil structure is typically found in surface soil (A horizons)?
granular
Soils high in organic matter (OM) commonly hold more available water than comparable soils with lower organic matter levels. This is most likely due to what characteristics of the high OM 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 soils are to be used for crop production, for which soil order would land drainage be most critical?
histosols
Information about conditions at 2 to 4 meters deep in a soil is usually most helpful for understanding___.
how best to design a building foundation.
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
A cover crop is usually grown for the purpose of _________.
improving soil quality and saving or recycling nutrients
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 is constrained by the presence of significant quantities of reactive ______.
iron
Brown and red colors in subsurface horizons are caused by _____ in the soil.
iron oxides
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
Land drainage is beneficial because _____.
it increases the depth of root penetration in the soil
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.
Which of the following statements about soil erosion is not true?
less than 20% of the total erosion in the US comes from croplands
Which of the following is not a characteristic of soil colloids?
low water holding capacity
Compared to upland soils, wetland soils would 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?
micorflora
Compared to the bulk soil in which the earthworms live, earthworm casts contain ____.
more of most plant available nutrients
Of the macronutrients, which can be most correctly said to be a renewable resource?
nitrogen
Which of the following is not a major factor in determining the soil aeration status?
nitrogen gas
If you want to maximize the quantity of vegetative cover on soil which of the following tillage practices would you use?
no-tillage
The matric potential of soil water is _____.
not influenced appreciably by the force of gravity
Concentrated animal production as is practiced in modern industrial agriculture usually results in ______.
nutrient excesses in the area of a livestock operation
Buffer strips principally function in nutrient management to _______.
prevent the transport of nutrients from fields to steams
A grass cover crop grown on cropland over the winter season in a humid temperate region can be expected to ______ .
reduce the amount of nutrients leached to the ground water
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
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
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 floods 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 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 properties?
series
Texture describes the ____ of particles in a soil.
sizes
Soils rich in which type of clay would provide the most troublesome site on which to build a home?
smectite
The universal soil-loss equation (USLE) suggests that soil erosion loss is a product of all but one of the following factors:
soil drainage
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
In most soils the overall population (numbers) of microorganisms changes with time, generally following changes in the _____.
supply of decomposable organic matter
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 differential 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
Soil tilth refers to _____.
the physical suitability of soil for plant growth
The likelihood of polluting groundwater with pesticides and plant nutrients is enhanced by ____ .
the present of macropores in the soil
A soil profile consists of _________.
the set of layers seen in a vertical cross section of soil
The key to preventing soil erosion by water on both farmland and landscaping job sites is ____.
to provide adequate surface and subsurface drainage
A soil developed in residual parent materials will likely have properties related to the properties of the rock below the C horizon. t/f
true
About one third of the readily accessible water in the hydrologic cycle is in the soil. t/f
true
Andisols are found mostly near recently active volcanoes. t/f
true
Compared to conventional tillage systems, most conservation tillage systems rely more heavily on herbicides to control weeds. t/f
true
Histosols generally have higher organic matter contents than Mollisols. t/f
true
In addition to plant nutrient ions, soil colloids also bind with water molecules, biomolecules (e.g. DNA, hormones, or antibiotics), viruses, toxic metals, pesticides, and a host of other mineral and organic substances in the environment. t/f
true
In his search for knowledge, Glen Rabenberg learned that many different sciences need to be involved to understand life - whether it be a plant, microbe, or animal. T/F
true
Most chemical fertilizers are inorganic salts.
true
Most irrigation systems are very inefficient with less than half the water that is taken from streams ever reaching the plants. t/f
true
Nitrogen fertilization is a significant cause of acidity in many cultivated soils. t/f
true
Osmotic and matric potentials are commonly negative because the soil water has a lower energy level than that of pure water t/f
true
Plants can be grown without any soil. t/f
true
Soil and crop management generally has a greater influence on evaporation from the soil surface (E) than on transpiration (T) from leaf surfaces. t/f
true
Soil colloids are too small to be seen with an ordinary light microscope. t/f
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. t/f
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. t/f
true
The leaf-like structure of silicate clays involves two kinds of horizontal sheets, one dominated by a plane of silicon atoms, the other by a plane of aluminum and/or magnesium. t/f
true
Tillage when the soil is too wet is likely to increase the soil bulk density. t/f
true
Vertisols are characterized by high contents of swelling-type silicate clays. t/f
true
Water will move from one site in a soil with a water potential of -5 kPa to an adjacent site with a water potential of -40 kPa. t/f
true
Soil occupies the ______part of the regolith.
upper
Among the soils of which order would you most likely find the highest buffering capacities?
vertisols
how to find 0M
wet soil weight-dry soil weight/ dry soil weight
