Pedology primarily studies:
A a) Soil use for engineering
B b) Soil genesis, classification, and morphology
C c) Soil prices in markets
D d) Soil for pottery
Pedology is the science of soil formation and classification in place.
The A horizon is typically characterized by:
A a) Bedrock
B b) Accumulation of clay (Bt)
C c) Topsoil rich in organic matter
D d) Calcium carbonate nodules
The A horizon mixes minerals with humus and supports roots.
“Parent material” in soil formation refers to:
A a) Organic matter only
B b) Weathered rock or deposits from which soils develop
C c) Only volcanic ash
D d) Only glacial till
It supplies minerals and texture to the developing soil.
Laterite soils are typically rich in:
A a) Calcium carbonate
B b) Sodium chloride
C c) Iron and aluminum oxides
D d) Organic nitrogen
Intense leaching in tropics leaves Fe/Al oxides, giving a reddish color.
The Soil pH indicating strong acidity is around:
A a) 3–5
B b) 6.5–7.5
C c) 8–9
D d) 10–11
Lower pH means higher acidity; neutral is ~7.
Cation Exchange Capacity (CEC) is generally highest in:
A a) Sandy soils
B b) Kaolinitic clays
C c) Organic-rich (humus) or smectitic clays
D d) Loess soils
Humus and 2:1 clays have many exchange sites for cations.
Which factor is not one of Jenny’s five soil-forming factors?
A a) Climate
B b) Organisms
C c) Relief (topography)
D d) Latitude lines
The classic factors are climate, organisms, relief, parent material, time.
“Illuviation” is the process of:
A a) Loss of material from a horizon
B b) Accumulation of material in a lower horizon
C c) Formation of bedrock
D d) Soil sterilization
Materials translocated from above deposit in the Bt/Bhs horizons.
A soil with 40% sand, 40% silt, and 20% clay is texturally a:
A a) Clay
B b) Sandy loam
C c) Loam
D d) Silt
Balanced sand–silt–clay proportions define loam.
Calcareous soils effervesce with dilute HCl primarily due to:
A a) NaCl
B b) CaCO₃
C c) Fe₂O₃
D d) Al₂O₃
Acid reacts with carbonate releasing CO₂ bubbles.
Soil structure refers to:
A a) Individual particle size
B b) Arrangement into aggregates (peds)
C c) Chemical composition only
D d) Color alone
Structure describes how particles form granules, blocks, prisms, etc.
The process leading to salt accumulation at the surface in arid soils is:
A a) Podzolization
B b) Salinization
C c) Laterization
D d) Gleying
Evaporation exceeds leaching, concentrating salts.
The USDA soil order with deep, dark, organic-rich surface horizons typical of grasslands is:
A a) Oxisols
B b) Mollisols
C c) Spodosols
D d) Histosols
They form under prairie vegetation with high base saturation.
Bulk density of a well-aggregated topsoil commonly ranges near:
A a) 0.2 g/cm³
B b) 0.6 g/cm³
C c) 1.2–1.4 g/cm³
D d) 2.5 g/cm³
Typical mineral topsoils fall in this range; higher indicates compaction.
A soil conservation practice that reduces erosion on slopes by following contour lines is:
A a) Strip mining