Soil Architecture and Physical Properties Exam Review

Flashcards covering key concepts related to soil architecture and physical properties as learned from the quiz.

What causes brown and red colors in subsurface horizons of soil?

Iron oxides.

Which soil separate is indicated by a sticky, putty-like feel?

Clay.

What type of soil structure is typically found in surface soil (A horizons)?

Granular.

Which type of soil structure is commonly found in sodium-rich subsurface horizons?

Columnar.

If a dry soil high in certain types of clay is moistened, what is likely to happen?

It is likely to swell up with enough force to crack pavements and building foundations.

What is commonly added to a silt loam soil to change its texture to that of a loam?

Sand.

In many soil profiles, why is the subsoil high in clay still permeable to percolating water?

Because prismatic structure may be well developed.

Practices that add organic matter and reduce tillage can significantly increase what in the soil?

Macropores

What is flocculation?

suspended particles clump together because the attractive forces between them overcome any repulsive forces caused by like surface charges

What indicates the brightness of a soil?

Hue, with a higher hue indicating good drainage.

What are typical colors for poorly drained (anoxic) mineral soils?

Low chromas.

What do fungal hyphae influence in soil structure?

They help stabilize soil aggregates.

What determines the texture of soil particles?

The arrangement of particles.

Which fraction of soils exhibits colloidal properties?

Clay.

What does a high hue indicate in soil color?

Good drainage.

What properties do soils with high silt content generally exhibit more than loamy sand soils?

Greater capacity to absorb gases, water, support bacterial growth, and release nutrients by mineral weathering

Texture describes the ___ of particles in a soil

sizes

What does the hue of the soil color indicate?

how red the soil is

EX: a hue of 2.5 means the color is 2.5 parts yellow to 1 part red