Soil, agriculture and food. 2 subtopics, 9 key terms.
Learn this topic properly. Interactive diagrams, worked examples, check questions and exam-style practice with mark schemes. Open “5 · Land” in FortyFive →
A mix of mineral particles, organic matter (humus), water, air and organisms.
Soil profile
The layers (horizons) of a soil: O, A, B, C.
Soil texture
The proportions of sand, silt and clay.
Soil degradation
Decline in soil quality: erosion, loss of nutrients, salinisation, compaction.
Soil as a system: inputs (organic matter, parent material, precipitation, energy), outputs (leaching, erosion, uptake by plants), transfers (biological mixing, translocation), transformations (decomposition, weathering, humification).
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Link each soil conservation method to the specific type of degradation it prevents.
5.2Agriculture and food
Key terms
Commercial vs. subsistence farming
Producing for sale / producing for the farmer's own family.
Intensive vs. extensive farming
High inputs per area / low inputs over large areas.
Food security
Reliable access to enough affordable, nutritious food.
Regenerative agriculture
Farming that restores soil health and biodiversity.
Food waste
Food lost or thrown away along the supply chain.
Farming systems are classified by inputs, outputs, scale and purpose: e.g. intensive beef feedlots vs. extensive nomadic herding; commercial monoculture vs. subsistence polyculture.
The full notes, worked example and check questions for this subtopic are in the app.
Exam tip: Use the energy flow argument (10% rule) to justify why diets matter for food security.