Français

Script 34.1

Script

How can you increase crop yields, reduce erosion and improve the soil? By putting a layer of mulch on the soil around your plants. Most mulch is made from plant residues left behind after harvesting. Today we are talking about how mulch can benefit you, your crops, and your soil. Advantages of mulch

Consider the advantages of using a mulch. A layer of mulch protects against soil erosion. When water drops hit soil particles the particles break into even smaller pieces. These pieces stick together and form a hard crust when the soil dries. This crust makes it difficult for water to soak into the ground. It is also hard for young plants to push through the soil crust.

A layer of mulch acts as a barrier which prevents rain from hitting the soil directly. This reduces the impact of the water drops on the soil and slows the water down before it hits the soil. This way the water has a chance to soak into the soil gradually. Water that soaks into the soil does not cause erosion because the water does not wash away the soil. On hillsides in Fiji, farmers reduced erosion by spreading palm fronds on the ground around the plants in their gardens.

Mulch also helps to keep moisture in the soil. In dry regions this is especially important. Mulch reflects a lot of the sun that otherwise beats down on the soil. This keeps the soil cooler so there is less evaporation.

More water in the soil means more water for the plants. For example, by using mulch, some Jamaican farmers were able to grow tomatoes and cucumbers where only drought tolerant crops grew before.

A layer of mulch placed between the rows and around the plants reduces weeds. Fewer weeds mean more water and soil nutrients for your crop. It also means that you will spend less time weeding. A final and important advantage of using mulch is that it adds organic matter to the soil as it decomposes. More organic matter means that the soil will hold water better. It also adds more nutrients to the soil.

What to use as mulch
There are many possible materials to use as mulch. For example you can use: straw, cut grass, leaves, rice husks, coffee pulp, plant stems, composted manure, newspapers, peanut shells, or seaweed. Do not use plant material from the same type of crops that you are growing. For example, maize residue should not be used as mulch for maize as it might still be carrying insects or diseases of maize. Experiment to see which mulches in your area last the longest. The longer the mulch lasts the less often you have to apply it. Plastic can be used but it is expensive and it will not decompose.

How to apply mulch
For large plants spread the mulch between the rows and around each plant. For small plants or seedlings apply the mulch between the rows. Be careful not to apply mulch too thickly because the seedlings will grow tall and spindly. Mulch that is too thick might also encourage disease or insects. Try different thicknesses of mulch to see which is best for your crop.

Disadvantages of mulch
There are some disadvantages to using a mulch. The biggest disadvantage is the time that it takes to cut, move, and apply the mulch. Mulches also slow down the drainage of water through the soil. In areas where there is a lot of rain, the extra moisture held by heavy mulching will encourage disease. So use less mulch and put it between the rows, not directly around the plants. This way you will not encourage disease but you will still reduce weeds.

The advantages of mulch are greater than the disadvantages. When you think of the extra work involved in applying mulch, remember that it also saves you time, improves your soil, and increases your yields.

Information Sources

Agriculture in the Tropics, C.C. Webster and P.N. Wilson, 1989, (640 pages). Longman Group UK ltd, Longman House, Burnt Mill, Harlow, Essex CM20 2JE, England.

Palm Fronds to the Rescue, African Farmer, no.3, April, 1990, (page 51). The Hunger Project, Global Office, One Madison Avenue, New York, New York 10010, USA.

Grass Mulch: An Innovative way of Gardening in the Dry Tropics, Scott Sherman, Echo Development Notes, no. 39, December, 1992, (pages 4 5). 17430 Durrance Road, North Fort Myers, Florida 33917 200, USA.

Bio Intensive Approach to Small Scale Household Food Production. International Institute of Rural Reconstruction, Biga, Silang, 4118 Cavite, Philippines.