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examBoard: Cambridge
examType: IGCSE
lessonTitle: Malnutrition and Famine Related to Soil Erosion
Soil erosion is one of the most serious environmental challenges facing our world today. When the fertile topsoil is washed or blown away, it doesn't just change the landscape it threatens our ability to grow food. This session explores how soil erosion contributes to malnutrition and famine around the world.
Key Definitions:
Soil is essential for growing about 95% of our food. Healthy soil contains nutrients that plants need to grow. When erosion occurs, these nutrients are lost, making it harder to grow crops. The UN Food and Agriculture Organization estimates that about one-third of the world's soil has already been degraded.
Every year, about 24 billion tonnes of fertile soil are lost due to erosion. It can take up to 1,000 years to form just 1 centimetre of topsoil naturally, but this can be washed away in a single heavy rainstorm if the land isn't protected.
When soil erodes, it affects food production in several important ways:
Eroded soil loses nitrogen, phosphorus, potassium and other nutrients that plants need to grow properly. This leads to stunted crops with lower yields.
Healthy soil acts like a sponge, holding water for plants to use. Eroded soil can't hold as much water, making crops more vulnerable to drought.
Shallow topsoil provides less space for plant roots to grow, resulting in weaker plants that produce less food and are more easily damaged by weather.
The path from soil erosion to human malnutrition follows a clear sequence:
This isn't just about having less food. When soil quality declines, the nutritional value of crops often decreases too. Modern studies show that fruits and vegetables grown today often contain fewer vitamins and minerals than those grown decades ago, partly due to soil degradation.
Not everyone is equally affected by soil erosion and the resulting food insecurity:
The people most vulnerable to malnutrition from soil erosion are:
Regions where soil erosion is contributing significantly to malnutrition include:
While malnutrition is a chronic condition affecting millions, famine represents an acute crisis. Soil erosion alone rarely causes famine directly, but it creates conditions where other triggers (drought, conflict, economic collapse) can push a region into famine.
Soil erosion contributes to famine risk in several ways:
During the 1930s in the American Great Plains, a combination of drought and poor farming practices led to catastrophic soil erosion. Strong winds created huge dust storms that blackened the sky. The resulting agricultural collapse contributed to the Great Depression and forced hundreds of thousands of people to migrate from Oklahoma, Texas and neighboring states. Many families faced severe malnutrition and the region's food production was devastated for years. This environmental disaster shows how quickly soil erosion can threaten food security even in a developed nation.
Haiti has lost over 98% of its original forest cover, largely due to clearing land for agriculture and cutting trees for charcoal. Without tree roots to hold soil in place, erosion has been severe. The country now has some of the most degraded soils in the world. This environmental damage has contributed to Haiti's food insecurity, with about half the population being undernourished. When natural disasters like hurricanes hit, the eroded landscape offers little protection, further damaging agricultural land and worsening food shortages.
Ethiopia has suffered from severe soil erosion, losing an estimated 1.5 billion tonnes of topsoil annually. In the highlands, where much of the population lives, steep slopes combined with deforestation have led to gullies that cut through once-productive farmland. This soil degradation has contributed to recurring food shortages and vulnerability to famine. During droughts, areas with heavily eroded soils are often the first to experience crop failures, as the degraded land cannot retain enough moisture to sustain plants.
There are proven ways to address soil erosion and reduce its impact on food security:
Techniques like contour ploughing, terracing, agroforestry and cover cropping can dramatically reduce soil erosion while maintaining or improving yields.
Teaching farmers about soil conservation techniques helps spread sustainable practices. Extension services and farmer field schools have proven effective in many countries.
Providing farmers with access to credit, insurance and markets gives them the resources to invest in soil conservation and recover from setbacks without resorting to harmful practices.
In Niger, a simple technique of protecting and managing naturally occurring tree seedlings has transformed 5 million hectares of degraded land. Farmers discovered that rather than clearing all trees from their fields (as was previously common practice), selectively maintaining certain trees improved soil fertility, reduced erosion and provided additional products like fruit and firewood. This farmer-led movement has increased crop yields, improved food security and made communities more resilient to drought. Studies show that villages practicing this approach suffered less malnutrition during recent droughts compared to those that didn't.
The relationship between soil erosion and human nutrition is clear:
Remember: It takes centuries to build healthy soil but only a few years to destroy it through poor management. The choices we make about how we treat our soil directly affect whether people have enough nutritious food to eat.
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