Stone Lines Reduce Erosion

Backgrounder

As a farmer you may live in a place where the land is dry. You might have noticed that soil blows around and that your crops don’t grow or are stunted. It may have started with a drought, or drought has made it worse, and you are worried that you will have to keep moving to find better land for farming.

You are not alone. Infertile land like this is spreading like a disease across many countries. This problem is called desertification. First the land loses its cover of vegetation. Without grasses and trees to help hold it in place, much of the topsoil blows away or is carried off by the rains. Only hard, dry land is left behind. But the problem can be fixed. Many countries have already taken steps to fight desertification and with your help its devastating effects can be stopped. Listen to the following – a technique which may help you and your neighbours regenerate the land, grow crops, and make a profit again.

Rainstorms can be intense sometimes, and when the rain falls hard, the water runs off the field instead of soaking into the soil. When this happens, rich topsoil is washed away as well.

Some farmers are saving their soil by building low walls called stone lines. Stone lines have many advantages. First, they keep water on your land. They also help keep soils fertile. The stones that you need to build the walls are free if you can find them nearby. And you don’t need any special equipment or machinery to build stone lines.

Stone lines are long rows of stones piled together to form barriers across your field. They do not store water. They do something else that is important if you want to prevent erosion. The stone lines slow the flow of water across your fields. They work on both flat and sloping land. The stone lines force the water to spread over the soil so that it can be absorbed into the soil instead of running off the field.

You must be ready to spend a lot of time building the lines. It is a good idea to make this into a group activity by inviting friends and neighbours to share the work. In the long term everybody will benefit. What you will be doing is building a little wall of stones across your field. It is important that you build the stone lines across the slope so that the water running down the slope slows down.

To begin making the stone lines, collect lots of stones, both small and large. Collect as many stones and rocks as possible. Now pile the stones in a line about 20 centimetres wide and 20 to 30 centimetres high. You do not have to cement the stones together. Just pile them loosely together across the length of the field.

On flat land, place the stone lines about 30 metres apart. On a slope, put them closer. Try to place the stone lines as close as possible to the contour lines of the slope. Contour lines are imaginary lines that run across a slope at the same height but do not run uphill or downhill. It is important to follow a contour line closely because you could actually increase the amount of erosion if you don’t.

Building the stone lines will be hard work but it will be worth the effort later on. Because the stone lines slow the movement of water, more water and soil will stay on the field where your crops are growing. The water and nutrients that stay in the field will benefit your crops.

Once you have built the lines you won’t have to do much to maintain them. You may know someone who has built a barrier made from earth rather than stone. It is easier to build an earth barrier than a stone line. But you will have to repair and improve the earth barrier more often. If you take the extra time now you will save time in the future.

Once the stone lines are in place you will soon realize the benefits. As trees and shrubs grow back, the soil will improve. Some local plants may start to grow alongside the stones and will help to slow runoff water and trap soil. You will notice that the wind blows less soil around. There will be more water for your crops because rainwater will stay longer in your fields. By keeping more soil, you also keep important organic material and nutrients as well.

Farmers in Africa report that they had a good crop in the first growing season after they built stone lines. This happened even where there was only barren ground the year before!