A Fertility Trench Holds Water in Dry Lands

Backgrounder

Does the soil in your garden get dry and hard in the dry season? Is it difficult to grow vegetables because you don’t have enough water? Some farmers with these problems grow very good gardens, even in the dry season. Here’s how they do it.

During the rainy season they dig a fertility trench. A fertility trench is a deep trench filled with layers of soil and organic matter. It’s like a compost pile, but underground. The rain that falls during the rainy season soaks into the soil in the trench. The organic matter in the trench holds the water for crops to use after the dry season begins. It is easy to make a fertility trench.

• First, you dig the trench. Dig a trench 1 metre deep and 1 metre wide. Make it about 6 metres long. You can make it longer if you want more growing space, but the first time you try this you probably shouldn’t make it too long.
• Next, gather some organic materials such as weeds and grass, crop residues, kitchen scraps, manure, bones, feathers, and anything else that will rot as time passes. Now put a 30 centimetre layer of these organic materials in the bottom of the trench. Thirty centimetres is approximately the distance from your elbow to your wrist. If you have some water to spare, sprinkle two buckets full of water over the layer of organic materials. The water will help the scraps and other organic material to rot.
• Next add a layer of soil 10 centimetres deep. Then add another 30 centimetre layer of organic matter. On top of that, put 10 centimetres of soil. Now put in enough organic matter to fill the trench up to ground level or just below ground level. If the fertility trench is sunk a bit into the ground, water can collect there very easily.
• Now cover the trench with a layer of grass and leaves to keep the soil from drying out. If you are farming or gardening on sloping land, even on a gentle slope, be sure to dig your trench along the contour. That is, dig across the slope, not up and down. Also, take any extra soil you have and form a mound on the downslope side of the fertility trench. This mound will collect some of the water flowing down the slope so that it can soak into the trench.

Five to six weeks after making the trench you can plant your first crop. The organic matter that’s in the trench soaks up water and holds it for a long time. Even during dry periods it holds water that your plants can use. And, as the organic matter in the trench rots, it adds good plant food to the soil.

After each harvest, dig the crop residues back into the ground. Try to grow a different crop every season. Also mix in other kinds of organic matter including kitchen waste and manure. This will enrich the soil and help it to hold water.

You can grow all sorts of crops on this fertility trench garden – sweet potatoes, tomatoes, peppers, okra, and even fruit trees. And while your plants are growing, all the organic materials that you’ve put into the trench below are turning into good plant food.