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