Chapter 3: Soil Classification

Soils in which of the following suborders would be more likely to occur in Minnesota than in Texas?

cryolls

A soil pedon is ______.

A three- dimensional unit that embodies the primary characteristics of an individual soil

Argillic horizons are characterized by _______.

Accumulation of silicate clays

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

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

Russia

The nomenclature of Soil Taxonomy is characterized by all but which one of the following statements?

The names give a clear indication of the modes of genesis of the soil

Which of the following diagnostic horizons would likely not restrict root growth in soils?

albic

Which soil moisture regime has the highest soil moisture levels?

aquic

Soil scientists generally map the soils in a landscape by sampling the soil in ______.

auger holes made mostly near expected soil boundaries

In soils of which great group would you most likely find wide surface cracks during periods of dry weather?

calciusterts

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

entisols

A pedon is a 3 dimensional field unit occupying about 1000 square feet (1 hectare) of land area.

false

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.

false

Epipedons are diagnostic subsoil horizons that are one of the primary means of classifying soils in the United States.

false

For agricultural use in a given region, a soil with an ochric epipedons could generally be expected to be more productive than one with a Mollic epipedons.

false

Soils classified as Inceptisols have the least well developed profiles in any order in the Soil Taxonomy system.

false

Soils in the Oxisols order are deeply weathered and have deep subsurface horizons of silicon oxide.

false

Spodosols are generally less acidic and less sandy than are Alfisols

false

The categories of Soil Taxonomy can be listed from the broadest (first) and most specific (last) as: order, suborder, great group, subgroup, series, family.

false

Which of the categories in the Soil Taxonomy system indicates properties that have implications for root growth as well as for the construction of building foundations?

family

Investigating the soils of northern Canada on summer, you dig a soil pit easily though fairly uniform peat material until, at 75 cm deep, your shovel hits a layer that is frozen solid. Into which type of soil are you most likely digging?

histel

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 soil temperature regimes would provide the warmest and least variable soil temperatures?

isohyperthermic

In which of the following epipedons is the organic matter level generally lowest?

ochric

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

oxic

The map units on a detailed soil map on Web Soil Survey 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

Soils in this order are commonly sandy in texture, quite acidic and develop primarily under coniferous trees in cool to cold climates

spodosols

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

true

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

true

An aquic soil moisture regime connotes a higher degree of soil moisture saturation than an ustic one.

true

An argillic horizon is a diagnostic horizon characterized by the subsurface accumulation of silicate clays.

true

Andisols are found mostly near recently active volcanoes.

true

Histosols generally have higher organic matter contents than Mollisols

true

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

true

Organic matter distribution in the profile is a significant criterion for differentiating epipedons.

true

Oxisols are more highly weathered than are the soils of any other order

true

Russian scientists were the first to develop the concept of soils as natural bodies.

true

The broadest category of classification in soil taxonomy specifies 12 soil orders, 11 of which are for mineral soils.

true

The family category focuses on properties affecting plant roots and suitability for engineering uses of soils.

true

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

true

The soil and a soil are two extremes in the concept of soils that is basic to most classification schemes.

true

The two 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

Vertisols are characterized by high contents of swelling-type silicate clays

true

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

true

Soils in which of the following soil suborders would most likely have a prominent E horizon under the A horizon?

udalfs

A soil has s thick black A horizon, a distinct B horizon, has reasonably stable soil structure, and was formed under grassland natural vegetation. In which suborder is it most likely classed?

udolls

You are seeking a soil with high clay content but one that is not sticky when wet nor hard and cloddy when dry. In which of the following suborders would you most likely find this soil?

ustox