Question 1

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

Accepted Answer

This statement is true. The two extremes in the concept of soils are the mineral soil and organic soil, which are differentiated based on their composition and properties.

Question 2

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.

Accepted Answer

A polypedon is a group of pedons with similar soil characteristics that are geographically proximate to each other, and it is similar in concept to a soil series in the United States. Therefore, the statement is true.

Question 3

Human influence on the formation of soils,such as many urban soils,is highlighted at what level in Soil Taxonomy?

Accepted Answer

Subgroup level in Soil Taxonomy is where human-altered or human-transported materials are highlighted, indicating significant human influence on soil formation.

Question 4

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.

Accepted Answer

The United States has a unique system of soil classification terminology that is not used in other parts of the world. Additionally, the classification system is based primarily on measurable soil properties such as texture, color, and structure.

Question 5

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

Accepted Answer

The distribution of organic matter in the soil profile is one of the main criteria for classifying epipedons, which are the uppermost soil horizons that exhibit some degree of soil formation.

Question 6

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

Accepted Answer

Mollisols are characterized by a thick, dark, nutrient-rich epipedon (surface soil layer) that is high in organic matter. This layer, called the A horizon, is usually at least 25 centimeters (10 inches) deep and sometimes as much as 100 cm (39 inches) deep.

Question 7

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?

Accepted Answer

The soil described is a Histel, which is a type of Histosol (organic soil) that remains frozen for more than two consecutive years. The presence of a frozen layer beneath peat material is characteristic of Histels, commonly found in cold regions like northern Canada.

Question 8

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

Accepted Answer

The name of a soil subgroup incorporates elements that reflect its order, suborder, and great group, providing a hierarchical classification within the soil taxonomy system.

Question 9

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

Accepted Answer

A mollic epipedon indicates a thick, dark topsoil that is high in organic matter and nutrients, making it more fertile and productive for agricultural use. An ochric epipedon, on the other hand, indicates a thin, light-colored topsoil that may be low in organic matter and fertility. Therefore, a mollic epipedon soil would be more productive for agricultural use than an ochric epipedon soil.

Question 10

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

Accepted Answer

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

Question 11

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

Accepted Answer

Calciusterts are soils with a high content of calcium carbonate which acts as a cementing agent, making the soil hard and compacted. Therefore, cracks easily form in dry weather when the soil becomes brittle and shrinks due to the lack of moisture.

Question 12

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

Accepted Answer

An aquic soil moisture regime is characterized by soil saturation for a significant portion of the year, while an ustic regime is typically only moderately moist for a shorter duration. Therefore, an aquic regime connotes a higher degree of soil moisture saturation than an ustic one.

Question 13

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.

Accepted Answer

Entisols can be highly variable because they are found in a variety of environments, from deserts to floodplains, each influencing their properties differently, unlike Andisols and Ultisols which are more specific in their formation conditions and thus have more consistent properties within their respective orders.

Question 14

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

Accepted Answer

Inceptisols have more developed profiles than Entisols, which are considered to have the least developed soil profiles in the Soil Taxonomy system.

Question 15

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

Accepted Answer

A pedon is a 3 dimensional field unit occupying a small area that varies depending on soil characteristics, typically ranging from 1 to 100 square meters. It is not equivalent to 1 hectare.

Question 16

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

Accepted Answer

Oxisols are deeply weathered soils but they have deep subsurface horizons of iron and aluminum oxides, not silicon oxide.

Question 17

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

Accepted Answer

Epipedons are diagnostic surface horizons, not subsurface, and they are indeed one of the primary means of classifying soils in the United States.

Question 18

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

Accepted Answer

There are 12 soil orders in Soil Taxonomy, and 11 of them are for mineral soils. The 12th soil order is for organic soils.

Question 19

Andisols are found mostly near recently active volcanoes.

Accepted Answer

Andisols are formed from volcanic ash and are therefore most commonly found near recently active volcanoes.

Question 20

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

Accepted Answer

The correct order is: order, suborder, great group, subgroup, family, series. Family comes before series, not after.

Quiz 3: Soil Classification