Environmental Systems and Societies · Topic 5: Land

ES5.1 — Soil

Environmental Systems and Societies · SL / HL · syllabus-mapped notes

1. Soil as a dynamic system

   Soil as a system with its own components and organisms, and the layered profile that develops over time.

2. Inputs, outputs, transfers and transformations

   What enters and leaves the soil system, the flows within it, and how to draw it as a systems diagram.

3. Soil in ecosystems: growth, biodiversity and carbon

   Soil as the foundation for plant growth and biodiversity, its role in element cycles, and as a carbon sink, store or source.

4. Soil texture and primary productivity

   How the mix of sand, silt, clay and humus is defined and measured, and how it controls productivity.

5. HL: Profiles, horizons and soil formation

   Classifying soils by profile, the O, A, B and C horizons, the value of the A horizon, and the five formation factors.

6. HL: Particle properties, soil analysis and carbon release

   Sand, silt and clay chemistry (CEC), the properties used to characterise a soil, and how soils release carbon.