IB Syllabus focus:
‘Land is finite; ~70% ice-free land is agriculture/forestry. Not all soils or terrains suit arable crops; suitability varies by biome, soils and climate.’
The availability of finite land resources and varying agro-climatic limits directly shape global agricultural productivity. Understanding these constraints is essential for sustainable food systems and environmental management worldwide.
Finite Land as a Resource
The Earth’s surface area is fixed, and human activity must compete for its use. Around 70% of the planet’s ice-free land is devoted to agriculture and forestry, making land one of the most heavily exploited natural resources.
This chart shows the global breakdown of land into glaciers, barren areas, and habitable land, and how habitable land is allocated to agriculture, forest, shrub/grasslands, and urban uses. It illustrates why finite land constrains food production and conservation. The figure also includes a livestock–cropland breakdown, which is extra detail beyond this subsubtopic. Source.
Competing Land Uses
Land is not only required for crop and livestock production but also for:
Urban expansion (cities, housing, infrastructure)
Industrial development (mines, factories, energy facilities)
Conservation purposes (national parks, biodiversity reserves)
Other ecosystems services (wetlands, floodplains, carbon storage)
The pressure to balance these competing uses highlights why land must be regarded as a finite and limiting factor in global development.
Agro-Climatic Limits
Agriculture is not equally possible everywhere. The productivity of land depends on biophysical factors and the climatic envelope in which it exists.
The Köppen–Geiger map shows the distribution of global climate zones that constrain crop choices and growing seasons. These zones underpin agro-climatic limits discussed in the notes. The map includes detailed climate classes beyond the syllabus’ minimum needs. Source.
Major Influences
Climate: Temperature, precipitation patterns, and seasonality determine what crops can grow.
Soil quality: Depth, nutrient availability, drainage, and pH affect suitability.
Topography: Flat terrain is more suitable for mechanised farming, while steep slopes are prone to erosion.
Water availability: Irrigation potential varies widely between regions.
Biome Suitability for Agriculture
Different biomes present contrasting opportunities and limitations for food production.
Tropical rainforests: Nutrient-poor soils due to rapid decomposition and leaching. Slash-and-burn has historically been used but is unsustainable long-term.
Grasslands: Deep, fertile soils (chernozems, mollisols) make them highly productive for cereal crops.
Deserts: Extreme water scarcity restricts cultivation unless supported by irrigation.
Tundra: Frozen soils and short growing seasons prevent large-scale agriculture.
Soil and Terrain Considerations
Soil Fertility
Soils vary in mineral content, organic matter, and structure, influencing agricultural suitability.
Rich loams are well-balanced for plant growth.
Sandy soils drain quickly but retain fewer nutrients.
Clay soils retain water and nutrients but can become waterlogged.
Soil Fertility: The capacity of soil to support plant growth by supplying water, nutrients, and a favourable root environment.
Terrain Constraints
Flat plains: Easy to cultivate, suitable for large-scale mechanisation.
Hilly or mountainous areas: Subject to erosion and often unsuitable for intensive farming.
Floodplains: Fertile due to regular silt deposition, but prone to flooding risks.
Climatic Classifications and Crop Suitability
Tropical Regions
Support crops like rice, maize, sugarcane, and bananas.
Require high rainfall and consistent warmth.
Temperate Regions
Well-suited to wheat, barley, oats, and potatoes.
Distinct growing seasons allow crop rotation.
Arid and Semi-Arid Regions
Depend heavily on irrigation for crops such as cotton, sorghum, and millet.
Risk of salinisation from over-irrigation.
The Role of Agro-Climatic Zoning
Agro-climatic zoning divides land based on temperature, rainfall, and soil properties to assess potential productivity. It provides:
Guidance for farmers on crop selection.
Government planning for agricultural policies.
Strategies for adapting to climate change impacts.
This world map depicts the fraction of each grid cell suitable for agriculture given temperature and soil constraints. It visualises spatial limits on arable potential across biomes and terrains. The classification scheme/colours are dataset-specific and include extra detail not required by the syllabus. Source.
Agro-Climatic Zone: A geographical area defined by shared climate and soil characteristics that determine the types of crops that can be grown successfully.
Sustainability Challenges Linked to Finite Land
Soil Degradation and Erosion
Overcultivation, deforestation, and unsustainable irrigation practices can degrade soils, reducing their long-term productivity.
Land Conversion
Expanding agriculture into forests and wetlands reduces biodiversity and carbon sequestration capacity.
Population Growth
Rising global populations increase food demand, intensifying pressure on finite land and requiring more efficient, sustainable agricultural practices.
Interconnection with Climate Change
Climate change alters temperature and precipitation regimes, shifting agro-climatic limits and crop suitability zones. Examples include:
Wheat belts moving polewards.
Desertification in semi-arid regions.
Melting permafrost potentially exposing new land, though often unsuitable for farming.
Key Takeaways for IB ESS Students
Land is finite; around 70% of ice-free land is already dedicated to agriculture and forestry.
Agro-climatic limits define where different crops can be successfully grown.
Suitability depends on biomes, soil fertility, terrain, and climate conditions.
Sustainable management of finite land resources is essential to balance food production, ecosystem services, and human development needs.
FAQ
Carrying capacity refers to the maximum population or agricultural output that a piece of land can sustain without long-term degradation.
It is determined by soil fertility, climate conditions, and available water resources. Exceeding this capacity can lead to erosion, nutrient depletion, or salinisation, reducing productivity over time.
Topography affects more than slope; it shapes microclimates, drainage, and soil formation.
Valleys may trap cold air or create frost pockets, reducing yields.
Elevated land can have thinner, less fertile soils.
Orientation (aspect) of slopes can affect sunlight exposure and evapotranspiration.
Subsistence farming typically adapts to local conditions, requiring fewer external inputs, while commercial agriculture often uses fertilisers, irrigation, and machinery to overcome limits.
This means land unsuitable for commercial-scale mechanisation may still support small-scale traditional practices. Conversely, commercial systems may exploit marginal land at higher environmental cost.
Limits are dynamic and change due to long-term climate variability and human activity.
Rising global temperatures can extend growing seasons in temperate regions.
Desertification and droughts can reduce suitability in semi-arid zones.
Deforestation can alter rainfall patterns, impacting local agriculture.
Land classification combines physical and climatic datasets.
Temperature ranges and rainfall totals are primary factors.
Soil texture, depth, and water-holding capacity are included.
Satellite imaging and GIS mapping are increasingly used to refine zones.
These classifications guide planning for sustainable crop allocation and land management.
Practice Questions
Question 1 (2 marks)
State two factors, other than climate, that influence the suitability of land for agriculture.
Mark scheme:
1 mark for each correct factor identified, up to 2 marks.
Acceptable answers include:Soil quality (nutrient content, depth, drainage, pH)
Topography (slope, terrain, risk of erosion)
Water availability (irrigation potential, proximity to rivers/groundwater)
Risk of natural hazards (flooding, drought, landslides)
Question 2 (5 marks)
Explain how agro-climatic limits influence global patterns of agriculture, using examples from different biomes.
Mark scheme:
Up to 2 marks for clear explanation of agro-climatic limits (temperature, rainfall, seasonality).
Up to 2 marks for linking limits to agricultural practices or crop types.
Up to 1 mark for use of relevant biome examples (e.g., grasslands supporting cereal crops, deserts requiring irrigation, tundra preventing large-scale farming).
Maximum 5 marks.
