Geography Soil

Morphology

The physical properties of soil; soils described by texture, structure, color, and others.

Soil texture

The feel of soil.

% of sand/silt/clay content, and the particle sizes. Clay as the smallest, silt has the second smallest, and sand has the largest.

Soil structures

Aggregates of individual soil particles, clumping from electrostatic attraction = especially in clay-rich soils.

changes dramatically

binding by salvia, feces, residues, precipitates, etc.

Prismatic structure

from repeated wetting and drying.

Clay soil, silt, not alot of sand. Moisture content. A type of soil structure characterized by vertical columns that arise from clay soil's expansion and contraction due to moisture changes.

Color

Varies considerably, even within the same soil.

Considerations: organic matter, types of minerals present, and moisture content.

Soil horizons

Roughly horizontal layers formed as a result of pedogenesis.

Horizons are different layers, telling you various things about the soil; being formed, minerals, moisture, texture,

Soil horizons usually have the same texture, structure, and color. Differences are hard to see as you go down.

Soil Horizon Characterizing

O: Organic Layer (plant litter, partially decomposed organic matter)

A: Organic matter + mineral grains (living creatures, inorganic minerals)

E: eluviated horizon, zone of leaching, materials move downward)

B: illuvial horizon (subsoil, iron, aluminum, accumlated and clay leeched down from A and E horizons.)

C: Parent material (stuff that provides the basic qualities and characteristics of soil profile)

Bed Rock is at the bottom, weathered parent material.

O and A horizon Development

Organic matter accumulates on the surface (O horizon) and mixes downward with mineral matter (A horizon)

Organic/Mineral layers

Provides a huge amount of nutrients and structure to the soil as it is decomposing.

Worms

Worms burrow through the soil mixing mineral and OM

Burrowing animals also move OM downward.

O horizon (organic)

Provides protection from rain, snow, and other natural events to preserve nutrients.

B horizon development

Physical movement of clay and other materials by water (Translocation) It is often referred to as the subsoil, accumulating minerals, organic matter, and nutrients leached from the upper layers.

What drives pedogenesis

Soils are the result of five factors CORPT

Climate, organicism, relief (topography), parent material, time.

Pedogenesis

The origin and development of soil from parent material.

It involves the transformation of rock (parent material) into soil through a combination of weathering, organic matter accumulation, and interactions with water, organisms, and climate.

important Controls of Soil formation

Parent material, time, climate, organisms, and topography

Parent Material

is the original geological material from which a soil forms. It can be rock, sediment, or organic material, and it plays a major role in determining the soil’s texture, mineral content, fertility, and development rate.

Most critical characteristic for soil formation

Water can chemically dissolve and move materials in soil

A Horizon - OM rich

E Horizon - iron, aluminum dissolved out

B horizon - iron, aluminum precipitation

C horizon - parent materials

Parent Material

is the original rock or material from which soil is formed. It can be solid rock or loose materials like sand and gravel. Over time, it breaks down to create soil.

Controls of soil formation

Climate, temperature, and precipitation (mostly rain)

Rates and depths of weathering

amount of precipitation influence the rate materials are leached from the soil

Tropical vs temperate soils.

Microorganisms

B horizon development

physical movement of clay and minerals from the upper horizons, resulting in the accumulation of materials such as iron and aluminum.

parent material

is crucial in determining the soil's characteristics and fertility, as it provides essential nutrients and minerals for soil development.

Organisms

Plants and animals including microorganisms

Organisms influence the soils physical and chemical properties

decaying plant and animal debris form organic acids.

critters mix and aerate a and b horizons

microorganisms convert nitrogen gas into soil nitrogen compounds.

Soil degradation

Activities which lower capacity of the soil to support life

Causes: agriculture, overgrazing, industrialization, deforestation. +d