IB Environmental Systems: Soil & Terrestrial Systems Revision

Soil & Terrestrial Systems is a core part of IB Environmental Systems. Revise the key concepts and common mistakes below, then lock them in with the free games.

Key concepts

Soil horizonsLayers O, A, B, C, R from organic litter to bedrock; differ in colour, texture, composition.

Soil texture triangleClassifies soils by % sand, silt, clay; loam is balanced and most productive (USDA classification).

Green Revolution1940s-70s adoption of high-yield varieties, fertilisers, irrigation; Borlaug Nobel 1970.

SalinisationSalt build-up in irrigated soils; reduces yield; estimated to affect over 60 million hectares globally.

Industrial agricultureMechanised monocultures, synthetic inputs; high yield but high fossil fuel and water use.

Food securityReliable physical, social, economic access to sufficient safe nutritious food (FAO 1996 definition).

Common mistakes to avoid

Questions where students often pick the tempting wrong answer — make sure you know the right one:

Is energy recycled within an ecosystem?✗ Yes, energy cycles round endlessly. ✓ No — energy flows through and is lost as heat; nutrients are recycled.

What does biodiversity measure?✗ Only the number of animals. ✓ The variety of all living things and their genes in an area.

Practise Soil & Terrestrial Systems — free games

Test yourself with these quick revision games for this topic:

▶ Two Truths, One Lie ▶ Reveal Race ▶ Connections Grid ▶ Falling Words ▶ Word Web

See all 17 games in the Subjects Arcade →

Soil & Terrestrial Systems

Key concepts

Common mistakes to avoid

Practise Soil & Terrestrial Systems — free games

More IB Environmental Systems topics