CPESC Soil Science 2

Question 1

Which soil particle size range defines silt according to the USDA classification system?

Accepted Answer

0.002–0.05 mm

Answer

USDA classifies silt as particles with diameters between 0.002 and 0.05 mm, finer than sand but coarser than clay.

Question 2

A soil with high shrink-swell potential is most likely dominated by which clay mineral?

Accepted Answer

Montmorillonite

Answer

Montmorillonite (smectite) has a 2:1 layer structure that allows water to enter between layers, causing significant shrink-swell behavior.

Question 3

What does the term 'cation exchange capacity' (CEC) measure in a soil?

Accepted Answer

The ability of soil to hold and exchange positively charged ions

Answer

CEC measures the total capacity of a soil to hold exchangeable cations, expressed in milliequivalents per 100 grams of soil.

Question 4

During a storm event, which soil structure type provides the greatest resistance to surface sealing and crusting?

Accepted Answer

Granular or crumb structure

Answer

Granular and crumb structures have numerous pores between aggregates that promote infiltration and resist surface sealing during rainfall.

Question 5

Which factor in the RUSLE equation accounts for the protective effect of plant cover on soil erosion?

Accepted Answer

C factor (Cover-management factor)

Answer

The C factor in RUSLE represents the ratio of soil loss from land with specified cover to that from tilled bare soil.

(CPESC) Certified Professional in Erosion and Sediment Control Practice Test