PLSS-210: Soil Science - Week 4 Questions

Silt size particles in the USDA system range in size from

0.002 mm - 0.05mm

A clay particle may have an equivalent diameter of:

1 micron

If 400cm3 of a soil weighs 500g, the bulk density is

1.25 Mg/m^3

In making a particle size analysis, the 40 second reading was 20g and the two hour reading was 15g. If a 50 gram sample was used, the silt content is:

10%

how many possible textural class names are there?

12

If a soil has 22% sand, 5% organic matter and 60% silt, the clay content of this soil would be given as:

18%

A soil weighing 90g had a total volume of 50 cm3. Assuming that the particle density oftypical mineral soil of 2.65g/cm3, the % pore space of this soil will be _____.

32%

In making a particle size analysis, the 40 second reading was 20g and the two hours reading was 15. If a 50 grams sample was used, the sand content is:

60%

In semiarid soils which of the following statements would adequately describe the general soilstructure patterns occurring in a soil profile?

A granular aggregation in the surface horizon with a prismatic or columnar type of structure in

When a soil has two or more colors present in a layer of soil, this would be an example of:

A mottled soil

A group of mineral soil particles with a definite upper and lower size limit defines:

A soil separate

The soil moisture regime of an aquoll is

Aquic

A soil which has an aridic moisture regime and an ochric or anthropic epipedon may mostprobably be classified as an _____.

Aridisol

Soil structure refers to:

Arrangement of primary soil particles to form aggregates

Different soils formed from the same parent material but at different topography are known as___________.

Catena

Which has the greatest specific surface:

Clay

Material that has been eroded down hill not in a channel and accumulated at the base of a slopeis classified as the following kind of transported material.

Colluvial

Minimum tillage is a type of tillage which:

Considerably reduces the number of soil manipulation operations

The ability of soil to resist crushing is known as:

Consistence

When one knows that a given soil horizon has a loam texture, one knows for sure that the horizon?

Contain less than 50% clay

As one moves away from the equator soils develope more

Darker hues

In which of the following soil orders will recent alluvium most likely be a common parent material

Entisols

In which of the following soil orders will recent alluvium most likely be a common parent material.

Entisols

Young soils will be mostly probably classified as

Entisols

Class structure refers to the shape of the peds.

F

Soil Taxonomy has 6 categories, the most specific of the categories is phase.

F

Soil texture is a dynamic property that is rather easy to change, whereas soil structure is a static soil property which changes very little.

F

Soils formed under coniferous forest will be more acid in the A horizon compared to those formed under deciduous forest because their leaves contain less Mg

F

The binding effectiveness of microbial gums is lesser than that of clay and organic matter.

F

The geological agent responsible for deposition alluvial parent materials is

Flowering water

A moraine is associated with

Glaciers

The hydrometer used in the particle size analysis (mechanical analysis) directly measures the:

Grams of silt and clay

Ustochrept is a soil ____________name.

Great group

The bulk density of a soil generally _____________ with depth.

Increases

Leaching is an example of:

Losses

A soil with 6oC and greater difference between summer and winter temperature and a meanannual soil temperature (MAST) between 8-15 oC will have a soil temperature regime.

Mesic

______ are the most significant in terms of aggregate cementation

Microbal gums

An epipedon that thick, dark colored, high in bases, has a strong structure will be classified as _.

Mollic

A Bt horizon will be probably closest to the _________ subsurface horizon

Mollic, Spodic

An epipedon that has light color, low in organic matter content, and hard and massive when dry _____ will most probably be a________ epipedon

Ochric

Soil colors of grey and blue indicates:

Poor internal drainage

The two Climatic variables have the greatest influence on soil formation are

Precipitation and Temperature

The major basis for classification of soil by the comprehensive soil classification system is:

Properties of horizon present

The major basis for classification of soil by the comprehensive soil classification system is:

Properties of horizons present

A subsurface horizon which has accumulation of Fe and Al oxides and organic matter will be a called a/an ___________ horizon

Spodic

The soils of the order vertisols are distinguished from other orders by:

Swelling clay content

As one moves towards to equator soil develop more reddish hues

T

Soils formed under grassland vegetation will be expected to have more organicmatter in their A horizons than those formed under forest vegetation.

T

Subsoil color is predominately the results of:

The form of iron present

Which of the following terms refers to the physical condition of the soil in its reaction to plant growth?

Tilth

Humification is and example of:

Transformation

Elluviation is an example of ?

Translocation

The subgroup name of Miami series, Typic hapludalf (Fine loamy, mesic, mixed) is

Typic hanpludalf

Soils that have argillic or kandic horizons and base saturation of less than 35% will be classified as

Ultisols

A soil is said to have a Munsell color chart of 7.5 YR 2/6. The 2 represents the ______.

Value

On the average, the bulk density of soils?

Varies inversely with porosity

Loess is a glacial deposit that has been moved into place by:

Wind

The geological agent responsible for deposition eolian parent materials is

Wind

Which has the greatest specific surface?

clay

Commonly soil tillage is for the purpose of:

controlling weeds ,

A soil texture is reported as a clay loam soil. Therefore it:

forms a strong ribbon greater than 2.5

Which type of structure will typically be found in surface (A Horizon) soils in Alabama?

granular

A soil separate is defined by

its size

The relative percent of sand, silt and clay , i.e. soil separates in soils describes the ____ of the soil

texture

When a 50-gram soil sample is used to make a particle size analysis and the 40 second is 10g/L, this means that

there is 20% of silt plus clay