But in IB ESS, soil is a living system with inputs, storages, transfers, and outputs. And when that system gets pushed past its limits, it doesn’t usually fail with drama. It fails slowly: a thinner topsoil layer after every storm, a little more salt after every irrigation cycle, a little less organic matter after every harvest.
That slow decline is exactly why soil degradation matters in IB ESS (2026 first assessment). It connects the syllabus threads students are always asked to link: food production systems, land use change, sustainability, ecosystem services, and human wellbeing.
An IB student tries to revise soil degradation by staring at a plant in a pot
Quick checklist: what you must be able to do for IB ESS
Before you memorise any case studies, make sure you can do these five things quickly (Paper 1 speed, Paper 2 clarity):
Define soil degradation as a loss of soil quality and function.
Name the main causes of soil degradation and explain the mechanism.
Link each cause to at least one consequence (environmental, social, economic).
Use at least one named case study with each cause (even briefly).
In IB ESS, soil degradation means the decline in soil’s ability to function as a system: supporting plant growth, cycling nutrients, storing carbon, filtering water, and providing habitat for organisms.
A useful exam phrasing is: soil degradation reduces fertility, structure, and biodiversity in soil, often lowering agricultural productivity and weakening ecosystem resilience.
If you need a quick refresh on how soil works as a system (horizons, inputs/outputs, transfers), use Notes for 5.1 Soil.
The main causes of soil degradation in IB ESS
Erosion (water and wind)
Erosion is the removal of topsoil by water or wind. In natural conditions it happens slowly, but human land use can accelerate it sharply.
Common accelerators you should mention in IB ESS answers:
Salinization happens when salts build up in soil, commonly in arid and semi-arid areas where irrigation water evaporates and leaves dissolved salts behind. Poor drainage makes it worse.
Why examiners like it: it’s a clean example of a human action (irrigation) creating an unintended feedback that reduces productivity.
Key impacts:
Osmotic stress for plants (harder to absorb water)
Reduced crop growth and potential long-term infertility
Named example often used: the Indus Valley region (Pakistan), where large-scale irrigation has contributed to widespread salinity issues.
A flooded field, salts hovering above, and a sad crop complaining
Nutrient depletion and loss of soil organic matter
Nutrient depletion occurs when crops remove nutrients faster than they are replaced. This is especially common with continuous monoculture, limited fallow time, and low organic inputs.
In IB ESS, link nutrient loss to:
Reduced soil fertility and yields
Greater reliance on fertilisers (economic costs, pollution risks)
Declining soil structure (less humus means weaker aggregates)
A common regional example is parts of Sub-Saharan Africa where nutrient-poor soils combined with intensive cultivation can exhaust fertility.
Desertification is land degradation in drylands driven by climate variability and human activity. In IB ESS, it’s not “deserts expanding by nature alone” -- it’s often about pressure on fragile soil systems.
Human drivers students should be ready to evaluate:
Overgrazing and fuelwood collection
Unsustainable cultivation of marginal lands
Poor water management
Key impacts:
Falling agricultural productivity
Increased food insecurity and migration pressures
Named case study: the Sahel (Africa), where variable rainfall plus land use pressure has contributed to desertification risks.
Pollution (toxins and excess chemicals)
Soil pollution can involve pesticides, hydrocarbons, industrial waste, or heavy metals. It reduces soil biodiversity, harms food chains, and can contaminate groundwater.
For IB ESS, focus on:
Why soil is a sink for pollutants
How pollutants move (leaching, runoff, bioaccumulation)
Trade-offs between agricultural productivity and environmental health
A named example sometimes used in environmental courses is Minamata (Japan) for mercury contamination impacts across ecosystems (including surrounding land).
Compaction
Compaction happens when heavy machinery or trampling compresses soil, reducing pore spaces.
Why it matters:
Less infiltration (more surface runoff)
Less oxygen in soil (reduced root growth and soil organism activity)
Greater erosion risk due to increased overland flow
It’s a straightforward mechanism question that can score well if you explain porosity clearly.
Heavy machinery squishing a sponge labeled SOIL while a worm protests
Human vs natural causes (what examiners want you to say)
You can mention droughts, storms, and floods as natural pressures. But most high-mark IB ESS responses make the key point: human activity often amplifies natural degradation processes.
A drought becomes a crisis when vegetation cover was already removed. A storm becomes topsoil loss when fields were left bare. A dryland becomes desertified when grazing pressure prevents recovery.
Closing: soil degradation is slow, but your progress doesn’t have to be
The main causes of soil degradation in IB ESS are easy to list: erosion, salinization, nutrient depletion, desertification, pollution, and compaction. The exam challenge is explaining each one as a system story: a pressure changes transfers and storages, then the consequences ripple into food production and sustainability.
If you want to revise IB ESS with less stress and more momentum, RevisionDojo is built for this exact loop: Study Notes for clarity, Flashcards for recall, Questionbank for exam practice, AI Chat for instant testing, and Grading tools to sharpen your responses. Add Predicted Papers, Mock Exams, and the Coursework Library when you’re ready to simulate the real thing, and Tutors when you want personalised feedback.
When soil degrades, it’s usually because small choices repeated over time became a big outcome. Your revision works the same way, in the opposite direction.
