Imagine a vast area of land. Now, picture nothing on it. No trees, no plants – just dust and cracked earth. How does land get to this state?
When rich earth that used to produce crops loses most of its fertility and becomes barren, we call the process desertification. That’s because the land becomes a desert. And for over 900 million people around the world, this is a big problem. Desertification causes food and water shortages and forces people to leave home and search for land they can farm.
What causes desertification?
Although many people think nature causes deserts through droughts, deserts are mostly made by people. There are four main ways people make deserts: by cutting down or burning trees, by letting animals overgraze land, by overcultivating land without nourishing it, and by using improper watering methods.
Farmers cut down or burn large areas of trees for a number of reasons: for fuel, for building materials, for pasture to let their animals graze, and for farmland. But the land that is cleared is usually only good for one or two harvests. That’s because the trees and plants that used to be there gave the soil a continuous supply of food and moisture, and their roots held the soil in place.
Trees and plants also protect the soil from pounding drops of rain. They are like a cover. But when this cover is gone, the soil is left exposed to the sun, wind and rain. The topsoil, where most of the nutrients are, is more likely to be blown away by wind or washed away by rain. Also, the rain that would normally be soaked up by the roots of trees and plants and into the soil rolls over the bare soil instead of soaking into it. So, this leaves the land dry, even after a heavy rain. This process is called soil erosion and it leads to deserts. Having less fertile land forces farmers to move on and clear more land, and the problem spreads.
Land can also turn to desert when farmers let their animals eat too many plants on their land. If allowed, animals will eat plants right down to the roots. If you see this happening to your plants and shrubs, remember to watch your animals and keep them on one piece of land at a time. Move them before the soil starts to look bare. Or you might want to keep your animals in large pens and bring the forage plants to them. This system, called zero grazing, keeps your animals from destroying all your vegetation. One plant that you can grow especially for this purpose is called Acacia albida. It grows quickly, fertilizes the soil and produces leaves that you can feed to your animals with good results.
One important way to prevent desertification is to make sure you return organic matter to the soil. If you plant too many crops that simply take nutrients from the land, the soil won’t have time to get back all its strength. The crops become poorer to the point where the land can’t produce any more. One way you can ensure that you have soil rich in nutrients is to grow cover crops and green manure crops between your main crops. After the harvest, turn the cover crops into the soil. Some examples of cover crops are velvet bean, sunnhemp, and clover.
While it seems that the easy solution to improve dry land is to bring lots of water to it, this can actually make the situation worse if it’s not done properly. Poor watering methods are the fourth main cause of deserts. All land needs a place for extra water to drain away. If water can’t drain properly, the excess water will just sit on top of the land and flood plant roots. Also, too much water from rivers or wells brought to the soil can leave salt deposits that will ruin the soil and kill most crops. If it drains away too fast, it may carry away precious topsoil.
So, now that we know what causes deserts, what is the solution?
There are no easy answers. The United Nations recently made an agreement called the “Convention to Combat Desertification” that was signed by over 100 countries. These countries agreed to look at ways to stop deserts from spreading and to listen to the suggestions of local people who live on drylands.
Farmers can stop deserts from spreading by carefully managing their land. If you have hilly land, you should be ploughing the land along the curves of the land, and around the hills, instead of straight up and down. Leave strips of grass between the cultivated rows. This stops the big problem of water rolling straight down the hills and taking soil with it. You can use crop residues such as banana leaves or vegetable waste from your kitchen as a mulch for your soil. Another thing you can do is to plant your crops by making a hole for each seed instead of ploughing the whole area. This takes more time of course, but it cuts down on damage to fragile soil. Adding compost and manure will also help keep your soil healthy so it doesn’t dry out, or die out.
Other scripts which describe soil conservation techniques are:
Soil erosion and overgrazing (Package 2, Script 6); Soil erosion and cropping on sloping, part 1: steep hillside land (4.7); Soil erosion and cropping on sloping, part 2: moderate and gently sloping land (4.8); Saving hillside topsoil, part 1 (5.7); Saving hillside topsoil, part 2 (5.8); Gully erosion, part 1: how gullies form (8.7); Gully erosion, part 2: prevention (8.8); Healing a gully (8.9A); Trench‑bed gardening for drylands (9.7); A garden instead of a gully (9.9D); Strip cropping can save soil and water (11.3); Building self‑forming terraces on sloping land (14.1); Soil moisture: why plants need it, how humus holds it (18.2); Tiny creatures improve soil for crops (21.7); How I turned abandoned farm land into good soil (22.1); Use earthworms for your farm and garden (23.6C); Soil conservation on Don Maximo Escobar’s farm; Preventing soil erosion (25.9); Good soil management increases harvests (26.9); Working with saline soil (27.11); Save soil on sloping fields (28.12); Where to find compost materials (33.9); More with mulch (34.1); Mulch increases yields at Sustenance Farm (34.2); Build and maintain contour ridges (37.3)
This script was written by Chris Szuskiewicz, a freelance writer in Toronto, Canada. It was reviewed by Kevin Perkins, Program Manager, Canadian Physicians for Aid and Relief in Toronto and Dr. Rorque Bryan, Faculty of Forestry at the University of Toronto
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