Glossary
A Horizon (Topsoil)
The layer beneath the O horizon, a fertile mixture of organic matter and minerals where most plant roots grow and biological activity is high.
Example:
Farmers highly value the A Horizon because its rich composition and biological activity are crucial for productive agriculture.
B Horizon (Subsoil)
The zone of accumulation, where leached minerals, clay, and iron from upper horizons are deposited and build up.
Example:
The reddish color of many soils is due to the accumulation of iron oxides in the B Horizon.
Bedrock
The solid, unweathered rock that lies beneath all soil layers and the C horizon.
Example:
Engineers must assess the stability of the bedrock before constructing large buildings or bridges.
Biological Activity (Soil Formation)
The role of living organisms, like mosses, plants, and microorganisms, in adding organic matter and nutrients to soil, contributing to horizon development.
Example:
Earthworms and decaying leaves contribute significantly to biological activity in the soil, creating humus and improving soil structure.
C Horizon (Parent Material)
The layer of partially weathered rock that lies beneath the B horizon, representing the initial stage of soil formation from bedrock.
Example:
Digging deep enough, you'll eventually hit the C Horizon, which consists of larger rock fragments that are slowly breaking down.
Deposition
The process by which new materials, such as organic matter or mineral particles, are added to the soil, often carried by wind or water.
Example:
After a flood, fine silt and clay particles are left behind on the floodplain through the process of deposition, enriching the soil.
Dust Bowl
A severe period of dust storms in the 1930s in the American and Canadian prairies, caused by drought and unsustainable farming practices that led to massive soil erosion.
Example:
The historical event of the Dust Bowl serves as a stark reminder of the devastating consequences of neglecting soil conservation.
E Horizon (Eluviated)
A light-colored zone of leaching, where water carries nutrients and minerals (like iron and clay) down to lower layers.
Example:
In some forest soils, a pale, sandy E Horizon is visible, indicating where water has washed away darker minerals.
O Horizon (Humus)
The uppermost soil horizon, composed primarily of surface litter and decaying organic matter, rich in nutrients.
Example:
Forest floors are often covered with a thick, dark O Horizon, made up of fallen leaves, twigs, and decomposing plant material.
Parent Material
The underlying geological material (rock) from which soil is formed through weathering processes.
Example:
Granite bedrock can serve as the parent material for sandy, acidic soils in mountainous regions.
Sediment Pollution
The contamination of waterways by eroded soil particles, which can cloud water, harm aquatic life, and clog channels.
Example:
Runoff from construction sites often leads to sediment pollution in nearby streams, making the water murky and impacting fish gills.
Soil
A complex, dynamic system composed of weathered rock, organic matter, water, and air that supports terrestrial life.
Example:
Healthy soil is essential for growing crops like corn and wheat, providing the necessary nutrients and structure for plant roots.
Soil Degradation
The overall decline in soil quality, including loss of fertility, structure, or increased salinity, often due to human activities.
Example:
Intensive farming without proper crop rotation can lead to soil degradation, depleting nutrients and reducing future yields.
Soil Erosion
The physical removal of topsoil by natural agents like wind or water, leading to loss of fertility and environmental damage.
Example:
Heavy rainfall on a deforested hillside can cause severe soil erosion, washing away valuable topsoil into rivers.
Soil Horizons
Distinct layers within a soil profile, each with unique physical, chemical, and biological characteristics, formed by various soil-forming processes.
Example:
A soil pit reveals several distinct soil horizons, from the dark topsoil to the lighter subsoil, each telling a story about the soil's history.
Vegetation (Erosion Prevention)
Plant cover that protects the soil surface from wind and rain and whose roots hold soil in place, significantly reducing erosion.
Example:
Planting cover crops and maintaining natural vegetation along riverbanks are effective strategies for preventing soil erosion.
Weathering
The process by which rocks and minerals are broken down into smaller pieces by physical (e.g., frost wedging) or chemical (e.g., acid rain) means.
Example:
Over centuries, the constant freezing and thawing of water in rock cracks leads to significant weathering, breaking down mountainsides.