soils

What is a soil profile?

A vertical section of soil showing the various horizons from the surface to the unaffected parent material.

What defines the A horizon in soil?

A layer approximately parallel to the surface that is distinguishable from adjacent layers by a distinctive set of properties produced by the soil process.

What is the O horizon composed of?

Organic material not mixed with minerals.

What are the three types of decomposed organic matter found in the O horizon?

Oi (decomposed), Oe (moderately decomposed), and Oa (highly decomposed).

What is the E horizon known for?

It is the zone of eluviation or leaching, usually underlain by the B horizon.

What does the B horizon indicate in soil formation?

It is a zone of illuviation, where materials leach from above horizons accumulate.

How does the C horizon differ from other horizons?

It is less affected by soil-forming processes and lies outside the zone of major biological influence.

What is Regolith?

Unaltered parent material, likely rock.

Why are E horizons more common in forests than in grasslands?

Greater rainfall and more acidic leaf litter in forests promote leaching.

What is the purpose of transitional horizons in soil classification?

They combine properties of two horizons, with the dominant one listed first.

What is a mollic epipedon?

A surface diagnostic horizon that is soft, contains >0.6% organic C, and has high base saturation, characteristic of grasslands.

What does base saturation indicate?

The percent of cation exchange capacity (CEC) occupied by base cations.

What are Entisols?

Recent mineral soils with little to no evidence of pedogenic horizons.

What defines Gelisols?

Soils with permafrost present within a specified depth.

What is a key feature of Vertisols?

They contain dark swelling and cracking clay, problematic for construction and agriculture.

What is the main soil type associated with extensive leaching in humid climates?

Ultisols, characterized by weathering of clays and leaching of base cations.

What is a defining characteristic of Spodosols?

Intensive acid leaching of coarse-textured parent material, with a diagnostic spodic horizon.

What are Oxisols known for?

They are the most highly weathered soils, typically found in humid and warm regions.