CWD Soil Science & Analysis 3

Question 1

Which redoximorphic feature in a soil profile is considered a depletion rather than a concentration?

Accepted Answer

Gray zones with low chroma surrounding root channels

Answer

Redox depletions are zones where iron and manganese have been leached out under reducing conditions, leaving low-chroma gray colors.

Question 2

What is the functional significance of hydrogen sulfide (H₂S) gas detected in a soil pit during a wetland delineation?

Accepted Answer

Confirms anaerobic conditions and microbial sulfate reduction

Answer

H₂S is produced by sulfate-reducing bacteria under anaerobic conditions and serves as a positive hydric soil indicator (F6 - Sulfidic Odor).

Question 3

Which soil texture class typically has the highest saturated hydraulic conductivity and drains most rapidly following flooding?

Accepted Answer

Coarse sand

Answer

Coarse sand has large pores and minimal capillary tension, giving it the highest hydraulic conductivity and fastest drainage rates.

Question 4

For the Histosol order, fibric organic material is defined as having what minimum fiber content after rubbing?

Accepted Answer

17%

Answer

Fibric material retains ≥40% fibers before rubbing but the post-rubbing threshold defining fibric vs. hemic is 17% fibers by volume.

Question 5

Which soil order is most commonly associated with wetland environments in the southeastern coastal plain of the United States?

Accepted Answer

Histosols

Answer

Histosols (organic soils) are abundant in southeastern coastal plain wetlands, such as the Everglades and Carolina bays, due to long-term waterlogging.

(CWD) Certified Wetland Delineator Practice Test

(CWD) Certified Wetland Delineator Practice Test

CWD Soil Science & Analysis 3