Managing soil erosion Revision Notes

Physical methods alter the landscape to slow down water runoff and trap soil particles, preventing their removal from the land. Terracing involves cutting flat platforms into steep slopes, which reduces the steepness and slows water flow. For example, rice farmers in mountainous regions create terraces to prevent soil loss during heavy rains.

Contour ploughing means ploughing along the natural contours of the land rather than up and down slopes. This creates ridges that act as barriers to water flow, reducing its speed and erosive power. A farmer ploughing along contour lines on a hillside can reduce soil loss compared to ploughing straight downhill.

Bunds are embankments or ridges built across slopes to trap soil and water. They act as physical barriers that hold back runoff, allowing water to infiltrate and soil to settle. For instance, small earth bunds constructed on a slope can capture sediment and reduce erosion downstream.

• Terracing creates flat steps on slopes to slow runoff.
• Contour ploughing follows land contours to reduce water speed.
• Bunds trap soil and water on slopes to prevent loss.

Vegetation cover protects soil by absorbing the impact of raindrops, reducing surface runoff, and anchoring soil with roots. Maintaining grass, crop residues, or natural vegetation prevents soil from becoming exposed and vulnerable.

Wind breaks are rows of trees or shrubs planted to reduce wind speed across open land. By lowering wind velocity, they prevent soil particles from being blown away, especially in dry, flat areas. For example, farmers plant lines of poplar trees around fields to act as wind breaks.

Tree planting stabilises soil through extensive root systems that bind soil particles together, reducing erosion risk on slopes and bare land. Trees also improve soil structure by adding organic matter through leaf litter.

• Vegetation cover shields soil from rain and wind erosion.
• Wind breaks reduce wind speed and protect exposed soil.
• Tree roots stabilise soil and improve structure.

Adding organic matter such as compost or manure enhances soil structure by increasing aggregation of soil particles. Well-aggregated soil has better porosity, allowing water to infiltrate rather than run off, which reduces erosion.

Organic matter also increases the soil’s water-holding capacity, helping plants grow better and maintain ground cover. For example, a farmer mixing compost into soil before planting crops improves soil stability and reduces erosion risk during rains.

• Organic matter improves soil aggregation and porosity.
• Better soil structure reduces runoff and erosion.
• Increased water retention supports healthy vegetation cover.

Tree planting within or around fields provides permanent root systems that stabilise soil and reduce erosion. Agroforestry systems combine trees with crops, enhancing biodiversity and soil protection.

Mixed cropping involves growing two or more crops simultaneously on the same land, which provides continuous ground cover and diverse root structures that protect soil.

Intercropping is a form of mixed cropping where crops are planted in alternating rows or patterns, reducing bare soil and improving soil stability. For example, planting maize with beans reduces soil exposure compared to monoculture maize fields.

• Tree planting stabilises soil with deep roots.
• Mixed cropping maintains continuous soil cover.
• Intercropping reduces bare soil and erosion risk.

Crop rotation is the practice of growing different types of crops in a planned sequence on the same land. Rotating crops prevents soil depletion and maintains soil structure by varying root depths and nutrient use.

For example, rotating deep-rooted legumes with shallow-rooted cereals improves soil aeration and organic matter content, reducing erosion risk. Crop rotation also disrupts pest cycles, promoting healthier crops and better ground cover.

• Crop rotation varies root systems to protect soil.
• It maintains soil fertility and structure.
• Rotation reduces erosion by sustaining healthy vegetation.