IB Environmental systems and societies Topic 5.1A Soil System Revision Notes (SL/HL)

IB Environmental systems and societies Topic 5.1A Soil System Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Soil Is a Dynamic System of Storages and Flows

Definition

Soil

Soil is a dynamic system that interacts with the atmosphere, hydrosphere, biosphere, and lithosphere.

Soil has five components: mineral particles, organic matter, water, air, and living organisms.
Their proportions shift with climate, parent rock, vegetation, land use, and time.
Because these components interact, soil behaves as a self-regulating system that responds to change.

Note

A healthy soil is about 50% solids and 50% pore space.
The pore spaces hold varying amounts of water and air.

The Five Components of Soil

Mineral Particles

Come from the weathering of parent rock and set the soil's texture (sand, silt, and clay).
They strongly influence fertility, pH, structure, and water-holding capacity.
Sand drains fast but holds few nutrients, while clay has a high surface area that grips water and nutrients.

Soil texture and its effect on productivity are covered in detail in 5.1C.

Organic Matter

Definition

Humus

Humus is a dark, crumbly substance that retains waterand nutrients, improving soil fertility.

Includes living organisms, fresh plant and animal residues, and humus (well-decomposed material).
Humus binds particles into stable aggregates that improve soil structure.
It raises nutrient-holding capacity, water retention, and aeration, and feeds soil organisms.

Analogy

Humus works like a sponge mixed with glue: it soaks up water while gluing particles together.

Water and Air

Soil water arrives from precipitation, irrigation, and capillary rise from groundwater.
Water fills pores and drives chemical reactions, nutrient transport, and weathering.
Air fills the pores not taken by water and supplies the oxygen roots and decomposers need.
Waterlogged soils lose their air, forcing anaerobic processes like denitrification that lower fertility.

Note

Balanced water and air is essential for a productive soil.
Too much water crowds out air and stresses roots.

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Definition

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(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

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Note

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Excepteur sint occaecat cupidatat non proident

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Tip

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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Soil Is a Dynamic System of Storages and Flows

Definition

Soil

Soil is a dynamic system that interacts with the atmosphere, hydrosphere, biosphere, and lithosphere.

Soil has five components: mineral particles, organic matter, water, air, and living organisms.
Their proportions shift with climate, parent rock, vegetation, land use, and time.
Because these components interact, soil behaves as a self-regulating system that responds to change.

Note

A healthy soil is about 50% solids and 50% pore space.
The pore spaces hold varying amounts of water and air.

The Five Components of Soil

Mineral Particles

Come from the weathering of parent rock and set the soil's texture (sand, silt, and clay).
They strongly influence fertility, pH, structure, and water-holding capacity.
Sand drains fast but holds few nutrients, while clay has a high surface area that grips water and nutrients.

Soil texture and its effect on productivity are covered in detail in 5.1C.

Organic Matter

Definition

Humus

Humus is a dark, crumbly substance that retains waterand nutrients, improving soil fertility.

Includes living organisms, fresh plant and animal residues, and humus (well-decomposed material).
Humus binds particles into stable aggregates that improve soil structure.
It raises nutrient-holding capacity, water retention, and aeration, and feeds soil organisms.

Analogy

Humus works like a sponge mixed with glue: it soaks up water while gluing particles together.

Water and Air

Soil water arrives from precipitation, irrigation, and capillary rise from groundwater.
Water fills pores and drives chemical reactions, nutrient transport, and weathering.
Air fills the pores not taken by water and supplies the oxygen roots and decomposers need.
Waterlogged soils lose their air, forcing anaerobic processes like denitrification that lower fertility.

Note

Balanced water and air is essential for a productive soil.
Too much water crowds out air and stresses roots.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 5.1A Soil System Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

Soil Is a Dynamic System of Storages and Flows

The Five Components of Soil

Mineral Particles

Organic Matter

Water and Air

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Soil Is a Dynamic System of Storages and Flows

The Five Components of Soil

Mineral Particles

Organic Matter

Water and Air

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account