Hesperian Health Guides

Preventing Erosion

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HealthWiki > A Community Guide to Environmental Health > Chapter 11: Restoring Land and Planting Trees > Preventing Erosion

Loss of soil, or erosion, is caused by wind and water wearing away the soil and carrying it off. Protecting soil from erosion, especially on steep hillsides, improves the land’s ability to grow crops, protects water sources downhill, and prevents landslides. Farmers follow 3 principles to prevent erosion and surface water runoff:

  1. Slow the water by creating natural barriers from the top of the watershed down.
  2. Spread the water by creating channels to divide it and direct where it flows.
  3. Sink the water by improving the soil so it allows the water to filter into the ground.

The signs of erosion are sometimes difficult to recognize. They include crops that do not produce as much as they used to, rivers that are muddier than they used to be (especially after storms), and soil that has grown thin.

Illustration of the below:2 men stand beside 2 gullies through a field: 1 narrow, 1 wide.
This erosion gully is just forming… …but before long, it will look like this.

Where erosion has not begun, it can be prevented by keeping as many plants and trees as possible, and by directing surface runoff water into ditches, ponds, and natural waterways. Where erosion is already severe, it is still possible to stop it and to restore healthy soils. Even placing a line of rocks or building a low stone wall across the slope of the land can prevent soils from washing downhill, and create fertile places for trees and plants. Sustainable farming methods such as green manures, crop rotation, mulching, and planting trees along with crops are also ways to protect soil and conserve water resources.

NGO workers learn about erosion from farmers
A woman talks with a farmer in a stony field.

In the Gulbarga District of Karnataka, India, an NGO worked with farmers to prevent soil erosion in their fields. Farmers traditionally built high stone barriers that collected most of the soil but had openings below to let water through, even when the monsoons came.

The NGO workers noticed that the farmers’ stone barriers allowed some soil to be lost to the fields below. And when high stone barriers were built at the lower edges of the field, some of the stones toppled over and had to be collected from below and replaced. They proposed building solid stone barriers that would stop all the soil loss and would not need constant repairs.

The farmers said they did not mind replacing a few stones. But the NGO workers could not understand this. The farmers’ stone barriers took more work to build and they let soil through, failing to control erosion completely. They proposed an experiment. In some fields they would build solid, low stone walls. In others the farmers would build the traditional barriers.

At the end of the season, the farmers and the NGO workers met and compared the effects. Many farmers with fields below the new, solid walls were unhappy. Cattle wandered across the low walls onto their fields, and after the monsoons, these farmers had less new soil and less water for rice paddies than before.

These problems led to arguments between the owners of the lower fields and the fields above. The experiment showed the farmers that their own traditional barriers worked better than the “improved” walls. The farmers told the NGO workers that the solid stone walls caused too many problems. Through this experience the NGO workers learned that the farmers’ traditional barriers not only prevented soil erosion, they also prevented cattle from straying. Allowing some soil and water through prevented good neighbor relations from eroding, which was more important to the farmers than a little extra work!