9.6 - Farming & Soil Erosion
The impact of farming on soil erosion
Farming practices have a significant influence on the environment, with soil erosion being one of the most pressing issues. This process affects both less economically developed countries (LEDCs), such as through water erosion in regions like Nepal, and more economically developed countries (MEDCs), for example, wind erosion in areas like Oklahoma. Soil erosion poses a major challenge because soil formation takes centuries, and once it is lost, it is incredibly difficult to restore.
Why soil erosion matters in agriculture
- Long-term formation - Soil develops over hundreds of years through natural processes, making its loss a critical concern for sustainable farming.
- Irreversible damage - Once eroded, replacing soil naturally or artificially is a slow and often impractical process.
- Global issue - It impacts agricultural productivity worldwide, reducing the land's ability to support crops and sustain livelihoods.
Causes of soil erosion in agricultural settings
Soil erosion in farming areas is primarily driven by the actions of wind and water. When soil is left exposed without protective cover, it becomes susceptible to being washed away by rain or blown away by strong winds. Certain farming practices can exacerbate this vulnerability, accelerating the loss of valuable topsoil.
Farming practices that contribute to soil erosion
- Ploughing on slopes - Tilling the land compacts the soil and forms channels that allow water to flow rapidly downhill, increasing erosion risk.
- Removal of natural barriers - Clearing hedgerows or windbreaks exposes soil to wind, making it easier for particles to be carried away.
- Deforestation for agriculture - Cutting down trees removes root systems that anchor soil, leaving it prone to damage from both wind and water.
- Monoculture and chemical use - Growing a single crop repeatedly and relying on chemical fertilisers depletes soil nutrients, preventing natural recovery and weakening soil structure.
- Overgrazing by livestock - When animals graze vegetation faster than it can regenerate, bare soil is exposed, heightening erosion risks.
Methods to minimise soil erosion in farming
To combat soil erosion, various techniques have been developed to protect soil and maintain agricultural productivity. These methods focus on reducing the exposure of soil to erosive forces and enhancing the land's ability to retain water and soil particles. While some of these approaches can be expensive and labour-intensive, they are essential for preserving farmland.
Techniques for reducing soil erosion
- Terracing on slopes - Creating flat, step-like platforms on hilly terrain, supported by walls, to hold water and soil in place, preventing rapid run-off.
- Contour ploughing - Ploughing along the natural curves of a hillside rather than straight up and down, slowing water flow and reducing soil loss.
- Shelter belts of trees - Planting rows of trees to act as windbreaks, with their roots stabilising soil and retaining moisture while blocking erosive winds.
- Strip farming practices - Growing different crops in alternating strips, harvested at staggered times, to ensure some soil remains covered by vegetation at all times.
- Stone lines along contours - Placing lines of stones following the land's natural contours to slow water run-off and trap soil particles.
- Stubble retention and intercropping - Leaving crop residue (stubble) on fields after harvest and planting new crops between rows to ensure continuous soil cover and enhance biodiversity.