Exam 1 Soil Science (Spring 18)

The osmotic potential would likely be lowest in soils of which of the following orders?

Aridisols

The process of aerobic respiration is a significant source of which of the following gases?

Carbon dioxide

A sticky, putty-like feel indicates a high percentage of which soil separate?

Clay

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 soil water potential is a measure of the potential of a soil to hold water.

False

The topmost horizon in most humid region forest soils is the A horizon.

False

The following are characteristics of a water molecule

Has a positive and a negative side

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

Unsaturated water flow ______.

Occurs on soils that are at field capacity

For any soil, the bulk density is always lower than the particle density.

True

Histosols 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

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

Mollisols are characterized by a deep epipedon that is high in organic matter

True

Plants can be grown without any soil.

True

THE soil and A soil are two extremes in the concept of soils that is basic to most clarification schemes.

True

The broadest category of classification in Soil Taxonomy specifics 12 soil orders, 11 of which are for mineral soils.

True

The mineral particles in soil consist of sand, silt, and clay.

True

The name of a subgroup indicate the order, suborder, and great group of which it is a member

True

The plasticity index is the difference between the plastic limit and the liquid limit.

True

The polarity of water helps account for the attraction of water molecules for each other.

True

The redox potential is a measure of the tendency of a substance to accept or donate electrons.

True

Which of the following describes a soil likely contain a significant content of low activity clays?

an Utisol in the Congo River basin in Africa

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

The transformation of gneiss into mica, quartz, and feldspar crystals is an example of

physical weathering and disintegration

Of the various types of drain systems, open ditch systems are most practical and economical for use on ________.

poorly drained soils with sandy profile

Some 60% of the water that is actively involved in the hydrologic cycle worldwide is found in soils.

False

Sprinkle irrigation is generally more efficient in the use of water than drip irrigation, especially for high valued crops.

False

The average residence time for water in clouds over the ocean is about one year.

False

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

Climate influences not only the rate of weathering but the type of native vegetation dominant in an area.

True

Early snowfall that arrives before the cold winter weather has frozen the soil generally increases the penetration of water into the soil.

True

The water potential at the leaf surfaces expressed in kPa is most likely to be _______.

-500

Which of the following pH values represents the most acid condition?

1.0

The evapotranspiration (ET) from a pine forest was found to be 50 cm during a growing season. If the evaporation from the soil surface during this period of time was 5 cm, what is the level of loss from leaf surfaces?

45 cm

In a typical mineral soil in optimal condition for plant growth, approximately what percentage filled with air?

50% water and 50% air

Hydoxyl ion concentrations are greatest in a soil solution with a pH value of ______.

6.5

For which substance would the particle density equal the bulk density?

A Quartz pebble

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= -30 ; B=-40

Because of their greater surface area per unit of soil mass, silt loams soils generally have a greater capacity than loamy sandy soils to ____.

Absorb water, Absorb gases, release nutrients by mineral weathering, and support bacterial growth

Which of the following is (are) essential plant nutrients?

Copper (Cu)

Which of the following processes are most apt to encourage good soil aeration?

Creation of more macro pores

Which of the following irrigation systems produces the most biomass per unit of water applied?

Drip irrigation

Where high-value crops or individual ornamental shrubs are to be grown and water is expensive, the most efficient type of irrigation to use would be ___________.

Drip or trickle

A chroma greater than 4 generally indicated a soil in good tilth.

False

A,B,C, and E horizons can be found in any true soil.

False

Although subsoil is more difficult to obtain, it is generally equally as good as topsoil for landscaping purposes.

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

Compared to a similar soil under native vegetation, a soil with a long history of conventionally tilled cropping would have less micropore space.

False

Eutrophication is enhanced by the pesticides in the water draining from agricultural soils.

False

Except for some kinds of foods, modern industry has made human dependence on soils a thing of the past.

False

Living organisms affect soil formation primarily by their constraining the level of oxygen in the soil.

False

Natural soils (as opposes to modern farm soils) can recycle organic compounds, but not inorganic elements.

False

Polysaccharides produced by soil microbes and similar synthetic polymers applied to soils are largely responsible for the crusts that form when rain follows tillage.

False

Respiration by plant and animal cells along with photosynthesis releases oxygen and consumes carbon dioxide.

False

Sandstones are examples of metamorphic rocks

False

Weathering of rocks usually is most intense in the center of a rock fragment, and gradually decreases toward the outside.

False

Igneous rocks can best be characterized as:

Formed from molten magma and include such common rocks as granite and diorite

Which type of soil structure is typically found in surface soil (A horizons?)

Granular

In which of the following "forms" of soil water are pesticides, excess plant nutrients and waste chemicals most apt to move through soils?

Gravitational

Soils high in organic matter commonly hold more available water than comparable soils with lower organic matter levels. This is most likely due to what characteristics of the high O.M. Soils?

Higher field capacity

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 necessary features for an area to be delineated as a wetland?

Hydric soils

Capillarity 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 soil

Iron oxides

Mechanical weathering processes result in:

Layers that appear much like the leaves of a cabbage.

Residual parent materials are best described as:

Materials formed by weathering of rocks and minerals in a place

In many soil profiles, the subsoil is high in clay, but is also quite permeable to percolation water. why?

Prismatic structure may be well developed

Most of the different nutrients essential for growth are supplied to plants directly from the _________.

Rain water

Which of the following actions would best assure good aeration in a soil?

Remove excess water

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.

Soil scientists from which country first conceived the idea that soils were natural bodies?

Russia

A soil profile consists of _______.

The set of layers seen in a vertical cross section of a soil

A polypedon or individual soil is a group of closely related peons that conceptually approximates what in the Untied States is called a soil series.

True

The two most significant characteristics of the classification system used in the United States are a unique system of terminology and focus on measurable soil properties as a primary basis for the classification.

True

The water potential at the field capacity for most soils is in the range of -10 to -30 kPa.

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.

True

You would be more apt to find a Gelisol in Alaska than in Iowa.

True

Igneous, sedimentary, and metamorphic are three

Types of rocks

Soil occupies the ______ part of the regolith.

Upper

Which of the following practices would encourage higher soil temperatures in the spring in a humid-temperature area?

Use a plastic mulch

Which of the following is not considered on of the five major factors influencing soil formation?

Valence state

Which soil moisture regime has the highest soil moisture levels?

aquic

Colloidal properties are exhibited by the ___fraction of soils.

clay

Urban development of land under natural vegetation or agriculture usually greatly _____ soil infiltration capacity and therefore greatly increases ______.

decreases, stream bank erosion

Granite is an example of a(n)

igneous rock

Which of the following subsurface diagnostic horizons would you expect to find in a highly weathered soil of the humid tropics?

oxic

The most common form of on-site waste water treatment for homes not hooked up to sewer lines is the ______.

septic tank and drain field

Texture describes the ____ of particles in a soil.

sizes

The likelihood of polluting groundwater with pesticides and plant nutrients is enhanced by _______.

the presence of macropores in the soil

A soil pedon is:

the smallest sampling unit that displays the full range of properties characteristic of a particular soil.

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

In which soil orders would recent alluvium most likely be a common parent material?

ustalfs