IB Biology Topic D4.2.7 Factors Affecting the Sustainability of Agriculture Revision Notes (SL/HL)

IB Biology Topic D4.2.7 Factors Affecting the Sustainability of Agriculture Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Soil Erosion Strips Away the Topsoil Crops Depend On

Definition

Soil erosion

Soil erosion is a gradual process of movement and transport of the upper layer of soil (topsoil) by different agents – particularly water, wind, and mass movement – causing its deterioration in the long term

When nutrient-rich topsoil is washed or blown away, crop yields fall and farmers grow more dependent on fertilisers.

Causes
1. Deforestation and overgrazing strip away plant cover and expose bare soil to wind and water.
2. Intensive tillage breaks down soil structure through frequent ploughing.
3. Poor water management lets uncontrolled irrigation wash soil off the land.
Solutions
1. Contour farming means planting along the natural contours of a slope to slow runoff.
2. Cover crops protect the soil between harvests and improve its structure.
3. Terracing cuts slopes into stepped fields that slow water flow.

Example

Terracing on China's Loess Plateau cut soil erosion by about 60 percent, restoring fertility and raising crop yields.

Leaching Drains the Nutrients That Keep Soil Fertile

Definition

Leaching

Leaching refers to the loss of water soluble plant nutrients from the soil due to rain and irrigation.

Water carries dissolved nutrients such as nitrates and phosphates down past the roots, leaving the soil less fertile.

Causes
1. Heavy rainfall or over-irrigation carries nutrients below the reach of plant roots.
2. Monoculture drains the same nutrients year after year by growing one crop repeatedly.
Solutions
1. Crop rotation alternates crops so nutrient use stays balanced.

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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.

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

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 nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

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

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

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 nisi ut aliquip ex ea commodo consequat.

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 Erosion Strips Away the Topsoil Crops Depend On

Definition

Soil erosion

When nutrient-rich topsoil is washed or blown away, crop yields fall and farmers grow more dependent on fertilisers.

Causes
1. Deforestation and overgrazing strip away plant cover and expose bare soil to wind and water.
2. Intensive tillage breaks down soil structure through frequent ploughing.
3. Poor water management lets uncontrolled irrigation wash soil off the land.
Solutions
1. Contour farming means planting along the natural contours of a slope to slow runoff.
2. Cover crops protect the soil between harvests and improve its structure.
3. Terracing cuts slopes into stepped fields that slow water flow.

Example

Terracing on China's Loess Plateau cut soil erosion by about 60 percent, restoring fertility and raising crop yields.

Leaching Drains the Nutrients That Keep Soil Fertile

Definition

Leaching

Leaching refers to the loss of water soluble plant nutrients from the soil due to rain and irrigation.

Water carries dissolved nutrients such as nitrates and phosphates down past the roots, leaving the soil less fertile.

Causes
1. Heavy rainfall or over-irrigation carries nutrients below the reach of plant roots.
2. Monoculture drains the same nutrients year after year by growing one crop repeatedly.
Solutions
1. Crop rotation alternates crops so nutrient use stays balanced.

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.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D4.2.7: Factors Affecting the Sustainability of Agriculture Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Soil Erosion Strips Away the Topsoil Crops Depend On

Leaching Drains the Nutrients That Keep Soil Fertile

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 Erosion Strips Away the Topsoil Crops Depend On

Leaching Drains the Nutrients That Keep Soil Fertile

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