Soils Exam 1
Compared to a similar soil under native vegetation, a soil with long history of conventionally tilled cropping would have less micropore space.
False
For any soil in which it is present, the C horizon is the parent material for the B horizon.
False
Proper timing of tillage is generally more difficult for a clayey than for a sandy soil.
True
Soil air usually has a higher carbon dioxide content than the air in the atmosphere.
True
Soils of good tilth and high productivity are usually characterized by stable aggregation and a high percentage of macropores.
True
The average residence time for water in clouds over the ocean is about one year.
False
Where organic matter constitutes only 1 or 2 percent of the soil by weight, it has only negligible influence on soil properties.
False
unsaturated water flow
Occurs on soils that are at field capacity
This is the most general category in the classification of soils in the United States.
Order
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
What part of the country are you likely to find the majority of the Mollisols?
Upper Midwest
Alfisols
have an argillic horizon AND is the most common soil order found in Arkansas
The plasticity index is the difference between the plastic limit and the liquid limit.
True
Which of the following pH values represents the most acid conditions?
1.0
Which of the following pH values represents a neutral condition?
7.0
The soils that are classified as 'udalfs' are in which soil order?
Alfisols
Silicate clay accumulation is most common in the _____.
B horizon
Which soil order has the least developed soils (youngest)?
Entisols
A soil developed in transported parent materials will likely have properties related to the properties of the rock below the C horizon.
False
Sandstones are good examples of metamorphic rocks.
False
Soil, like concrete and steel, is a standard construction material. Its properties are well characterized and predictable so that standard building foundation designs can be used uniformly at all building sites of a given topography.
False
Soils developed in wind-blown parent materials such as loess are generally of little agricultural value.
False
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 value crops.
False
Subsoil is typically equivalent to the O horizons.
False
The property of cohesion in water stems from the attraction of water molecules for soil solids.
False
The topmost horizon in most humid region forest soils is the A horizon.
False
Which type of soil structure is typically found in surface soils (A horizons)?
Granular
Information about conditions at 2 to 4 meters deep in a soil usually most helpful for understanding?
How best to design a building foundation.
Using a textural triangle chart, it can be determined that a soil with 45% sand and 20% clay belongs to the _____ textural class.
Loam
Practices that add organic matter and reduce tillage can be expected to most significantly increase the ______ in a soil.
Macropores
The percentages of which soil components represent the minimum information necessary in order to determine the textural class of a soil?
Silt & Sand
Vertisols
Soils with high content of shrink-swell clays.
Gelisols
Soils with permafrost
Climate influences not only the rate of weathering by the type of native vegetation dominant in an area.
True
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
For which substance would the particle density equal the bulk density?
a quartz pebble
The water in the soil typically differs from pure water because the soil water _____.
all of the above
Mollisols
dark colored soils of the prairies
Capillarity in soils _____.
involves both adhesion and cohesion.
Residual parent materials are best described as _____.
materials formed by weathering of rocks and minerals in place
Igneous rocks can best be characterized as:
rocks formed when molten magma solidifies
Alluvial fans are usually characterized by _____ soils.
sandy and gravelly
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 of minerals
Plant transpiration efficiency at a given location is markedly influenced by ______.
the plant species being grown and Fertilization practices used
Which of the following statements is not correct?
tropical forests protect the soil from excessive weathering
In which of the following situations would you expect downward movement of soil water through the profile to be most rapid?
uniformly textured sandy loam profile
