CH Soil Science & Analysis 3

Question 1

A soil survey report describes a unit as 'somewhat poorly drained.' Which water table depth range typically corresponds to this drainage class?

Accepted Answer

Between 30 and 90 cm below surface

Answer

Somewhat poorly drained soils typically have a seasonal high water table between 30 and 90 cm, causing intermittent saturation in the upper profile.

Question 2

Which soil order in USDA Soil Taxonomy is defined primarily by the presence of a spodic horizon?

Accepted Answer

Spodosols

Answer

Spodosols are defined by the presence of a spodic horizon—an illuvial accumulation of amorphous organic-aluminum-iron complexes.

Question 3

The 'van Genuchten model' is used in hydrology to describe:

Accepted Answer

The soil water retention curve relating matric potential to volumetric water content

Answer

The van Genuchten model provides a mathematical equation fitting the relationship between soil matric potential and volumetric water content in the retention curve.

Question 4

In soil horizon designation, which master horizon letter indicates a zone of maximum biological activity and organic matter accumulation?

Accepted Answer

A

Answer

The A horizon is the surface mineral horizon where organic matter accumulates and biological activity is highest.

Question 5

A hydrographer observes mottles with Munsell chroma ≤2 within 50 cm of the soil surface. This most likely indicates:

Accepted Answer

Seasonal saturation and reducing conditions causing iron reduction

Answer

Low chroma (≤2) mottles indicate redoximorphic features formed under seasonal anaerobic conditions where iron is reduced and mobilized.

(CH) Certified Hydrographer Practice Test

(CH) Certified Hydrographer Practice Test

CH Soil Science & Analysis 3