ENST200 chapter 1

Ecological roles of soil in Ecosystems: Medium for plant growth

• Soils support the plants that make the built environment livable

• soils grow 95% of the food we eat

• soils support the plants that we use to make things (EX: Trees for wood)

• Plants can replace petroleum to make chemicals & fuels to drive our economy

Ecological roles of soil in Ecosystems: Recycling system for nutrients

• Carbon and nitrogen cycling

• Turning organic waste into soil organic matter and then mineral nutrients to be utilized by plants and animals

Ecological roles of soil in Ecosystems: Modifier of the atmosphere

soils emit and/or absorb

• dust

• heat

• water vapor

• CO2

• oxygen

• methane

• nitrogen oxides

• odors

• other gases

Ecological roles of soil in Ecosystems: Habitat for soil organisms

• earth worms

• microorganisms (fungi, bacteria, etc)

Ecological roles of soil in Ecosystems: Engineering medium

• rammed earth houses

• mud bricks

• foundation on what infrastructure is built on

Ecological roles of soil in Ecosystems: System for water supply & purification

• water purification

• water runs into bodies of water (rivers, streams, lakes, etc)

The 6 Ecological roles of soil in Ecosystems

• Medium for plant growth

• Recycling system for nutrients

• Modifier of the atmosphere

• Habitat for soil organisms

• Engineering medium

• System for water supply & purification

Pedosphere

• Atmosphere (soil air): gasses- CO2, oxygen, nitrogen

• Biosphere (organic matter and biomass): plants, animals, microbes, their products and remains

• Hydrosphere (soil water): water and dissolved substances

• Lithosphere (soil particles): minerals in rocks, clays, sediments

Regolith

• Layer of weathered rock

• Soft part of the soil

Solum

O, A, and B horizon portion of soil

Bedrock

parent material, unweathered rock

Saprolite

soil that has been weathered to the point that it is loose enough to be dug with a spade

O horizon

top organic layer at soil surface

A horizon

layer after O horizon, accumulation of organic matter that has darkened, dominated by mineral particles

E Horizon

below A horizon (not all soils have them), intensely weathered and leached mineral horizon, light colored, eluvial-washout

B horizon

accumulation of materials washed down from horizons above, illuvial- wash into

C horizon

least weathered part of soil profile

R horizon

hard rock, parent material

Macronutrients

used in relatively large amounts

mostly from air and water

• CO2

• Hydrogen

• Oxygen

Mostly from soil solids

• nitrogen

• phosphorus

• potassium

• calcium

• magnesium

• sulfur

micronutrients

used in relatively small amounts

derived from soil solids

• iron

• maganese

• zinc

• copper

• cobalt

• nickel

• chlorine

• molybdenum

• boron

• silicon

What plants get from soils

• air

• water

• temperature moderation

• physical support

• nutrients

• medium for bio-signals

• toxin free medium

Nutrients obtained from soil minerals

• phosphorus

• potassium

• calcium

things obtained from air

• nitrogen

• co2

• different gasses

things obtained from soil organic matter

• nutrients like nitrogen, phosphorus and sulfur

soil solution

soil water that contains dissolved organic and inorganic substances

humus

collection of organic compounds that accumulate in soil when when partially broken down plant and animal matter are protected from complete decay by various factors in the environment

diffusion

nutrient ions moving from areas of high concentration to nutrient-depleted areas of lower concentration

root interception

when roots grow and touch soil particles to absorb nutrients’ as they grow (not done on purpose just something that happens)

mass flow

when dissolved nutrients are carried along with flowing soil water toward a root that is actively drawing water from the soil

soil colloids

microscopic minerals and organic particles that drive most of the chemical and physical activity in soil