IB Environmental systems and societies Topic 5.1G Soil Properties Revision Notes (HL)

IB Environmental systems and societies Topic 5.1G Soil Properties Revision Notes (HL) | RevisionDojo

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Measurable Properties Decide a Soil's Fertility

Beyond texture, a soil's fertility is set by several measurable properties.
These include cation exchange capacity, organic matter, moisture, bulk density, colour, and pH.

The proportions of sand, silt, and clay (texture) are covered in 5.1C.

Cation Exchange Capacity: How Soils Hold Nutrients

Definition

Cation-exchange capacity (CEC)

Cation-exchange capacity (CEC) is the ability of a soil to hold positively charged ions due to negatively charged particles like clays and humus.

Cation exchange capacity (CEC) is a soil's ability to hold positively charged nutrient ions such as calcium, magnesium, and potassium.
Clay and humus carry many negative charges, giving them high CEC, while sand has few and has low CEC.
Together, clay and humus form the clay-humus complex, the main site of nutrient exchange.
Plant roots release hydrogen ions that swap places with nutrient cations held on the complex.
High-CEC soils are generally more fertile, as long as aeration lets roots reach the nutrients.

Analogy

Sand is like a basket with big holes, silt a colander with medium holes, and clay a cloth bag with tiny pores.
The smaller the pores, the more water and nutrients stay inside.

Comparing Sand, Silt, and Clay

Texture sets the baseline for the properties below, as this comparison shows.

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Definition

Paywall

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

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Duis aute irure dolor in reprehenderit

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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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Measurable Properties Decide a Soil's Fertility

Beyond texture, a soil's fertility is set by several measurable properties.
These include cation exchange capacity, organic matter, moisture, bulk density, colour, and pH.

The proportions of sand, silt, and clay (texture) are covered in 5.1C.

Cation Exchange Capacity: How Soils Hold Nutrients

Definition

Cation-exchange capacity (CEC)

Cation-exchange capacity (CEC) is the ability of a soil to hold positively charged ions due to negatively charged particles like clays and humus.

Cation exchange capacity (CEC) is a soil's ability to hold positively charged nutrient ions such as calcium, magnesium, and potassium.
Clay and humus carry many negative charges, giving them high CEC, while sand has few and has low CEC.
Together, clay and humus form the clay-humus complex, the main site of nutrient exchange.
Plant roots release hydrogen ions that swap places with nutrient cations held on the complex.
High-CEC soils are generally more fertile, as long as aeration lets roots reach the nutrients.

Analogy

Sand is like a basket with big holes, silt a colander with medium holes, and clay a cloth bag with tiny pores.
The smaller the pores, the more water and nutrients stay inside.

Comparing Sand, Silt, and Clay

Texture sets the baseline for the properties below, as this comparison shows.

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 5.1G Soil Properties 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

Measurable Properties Decide a Soil's Fertility

Cation Exchange Capacity: How Soils Hold Nutrients

Comparing Sand, Silt, and Clay

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

Measurable Properties Decide a Soil's Fertility

Cation Exchange Capacity: How Soils Hold Nutrients

Comparing Sand, Silt, and Clay

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