Agricultural systems vary because local soil and climate conditions determine which organisms can grow, their productivity, and the inputs and techniques farmers need. Physical conditions also interact with economic, technological and sociocultural factors.
This is IB ESS subtopic 5.2 Agriculture and food. The general relationship is required at SL and HL, while evaluating contrasting choices caused by local soils and climate adds explicit HL depth.
| Environmental factor | Effect on agriculture | Example or response |
|---|---|---|
| Soil texture | Sandy soils drain rapidly but retain fewer nutrients; clay-rich soils retain water and nutrients but may become waterlogged. | Add organic matter, install drainage or select drought-tolerant crops. |
| Soil fertility and pH | Nutrient availability and pH affect plant growth and productivity. | Apply fertilizers or lime and use crop rotation. |
| Temperature | Temperature controls growing-season length, photosynthesis and frost risk. | Tropical regions may support multiple harvests; colder regions have shorter seasons. |
| Rainfall | Rainfall amount and seasonality influence irrigation needs and crop choice. | Monsoon climates support paddy rice; dry regions favour pastoralism or irrigation. |
| Climate variability | Droughts, floods and unpredictable seasons increase crop-failure risk. | Diversify crops, store water or adopt drought-resistant varieties. |
Flooded rice cultivation is widespread in monsoon regions of South and Southeast Asia because warm temperatures and seasonal rainfall provide suitable conditions. In the Sahel, low and unreliable rainfall favours drought-tolerant crops and extensive pastoralism, although overgrazing and climate change can increase land degradation.
A common misconception is that soil and climate completely determine farming. They create opportunities and constraints, but choices also reflect markets, technology, labour, culture, policy and access to capital. Environmental justice matters because poorer farmers may lack irrigation, improved seeds or insurance needed to adapt.
Exam technique: For an “explain” question, link each condition to an agricultural consequence using cause-and-effect language. At HL, compare two named systems and explain both physical and human influences rather than merely listing crops.