Exam 1 Study Guide: Soil Science Fundamentals

Comprehensive vocabulary flashcards covering the ecological functions, pedogenesis, taxonomy, physical properties, and biology of soils from Chapters 1 through 5.

Soil quality

Also called soil health; the ability of soil to support plants, people, and natural ecosystems over time.

Soil degradation

The loss of soil quality due to erosion, pollution, salinization, or loss of organic matter.

Pedon

An individual section of soil.

Polypedon

A collection of pedons.

CLORPT

A mnemonic representing the five soil-forming factors: Climate, Living organisms, Relief, Parent material, and Time.

Parent material

The original material from which soil forms.

Relief

A soil-forming factor referring to the slope, landscape position, and drainage conditions of the land.

Additions

A soil-development process wherein new materials enter the soil.

Losses

A soil-development process wherein materials leave the soil.

Translocations

A soil-development process wherein materials move within the soil profile.

Transformations

A soil-development process wherein materials change into different forms.

O horizon

The master soil horizon composed of organic material.

A horizon

The topsoil layer in a soil profile.

E horizon

The soil layer from which materials are removed by eluviation.

B horizon

The subsoil layer in a soil profile.

C horizon

The weathered parent material layer located below the subsoil.

R horizon

The unweathered bedrock layer underlying the soil profile.

USDA Soil Taxonomy

The classification system grouping soils by their properties into categories from broadest to narrowest: Order → Suborder → Great group → Subgroup → Family → Series.

Mollisols

One of the 12 USDA soil orders; characterized as grassland soils.

Histosols

One of the 12 USDA soil orders; characterized as organic soils.

Aridisols

One of the 12 USDA soil orders; characterized as dry-climate soils.

Soil capability Class I

The land capability class describing soils with few limitations for farming.

Soil capability Class VIII

The land capability class describing soils generally unsuitable for cultivated crops; better suited to uses such as wildlife or recreation.

Soil texture

The relative percentage of sand, silt, and clay in a soil.

Sand

The largest soil mineral particles; drains quickly.

Silt

Medium-sized soil mineral particles; holds plant-available water well.

Clay

The smallest soil mineral particles; holds water and nutrients but often drains slowly.

Permeability

How easily water and air move through the soil.

Infiltration

Water entering the soil surface.

Percolation

Water moving downward through the soil profile.

Porosity

The total amount of pore space in a soil.

Macropores

Large soil pores that help air and water move.

Micropores

Small soil pores that hold water.

Soil structure

The manner in which individual soil particles group together into aggregates.

Granular structure

A soil structure type characterized by rounded aggregates.

Platy structure

A soil structure type characterized by flat, plate-like aggregates.

Blocky structure

A soil structure type characterized by block-shaped aggregates.

Prismatic structure

A soil structure type characterized by vertically elongated aggregates.

Soil density

How much soil mass occupies a certain volume.

Soil consistence

How soil behaves and resists deformation when pressure is applied.

Soil compaction

The squeezing together of soil particles by pressure, reducing pore space and limiting water, air, and root movement.

Tilth

The physical condition of soil suited for planting and root growth.

Carbon cycle

The continuous movement of carbon between plants, soil, and the atmosphere.

Soil food web

The network of organisms that feed on plants, organic matter, and one another, helping decompose material and recycle nutrients.

Actinomycetes

Soil bacteria that physically resemble fungi.

Microflora

A classification of soil organisms comprising bacteria, fungi, actinomycetes, and algae.

Microfauna

A classification of microscopic soil animals, including protozoa.

Mesofauna

A classification of intermediate-sized soil animals, including many nematodes and arthropods.

Macrofauna

A classification of larger soil animals, including earthworms and some mammals.