Green Manuring: Using Legumes for Plant Beds

We use green manuring to help with our composting. Green manures allow us to fertilize and add more organic matter to our soil. Green manuring is a method of putting back into the soil living plants at the peak of their growth. We do this by using leguminous plants (like mung bean, kadios, peanut and other wild plants) or we also use wild sunflowers. The plants are harvested at their peak or right before they flower, and then the plants are ploughed back into the soil. This process brings in more nitrogen, organic matter and living plants into the soil. Legumes for example take in a lot of nitrogen from the air through the bacteria that live in their roots. Grasses also create green matter, which breaks down into humus. So what we are doing here is a method of composting on the bed itself.

The limitation of green manuring though is that you are not able to control the quality of humus in the soil. It also does not necessarily improve the soil’s structure long term. In fact, the wrong use of green manuring can decrease the soil’s organic content.

How to Green Manure:

1. Plant your leguminous seeds. Water until germination occurs. Then water constantly.
2. When the plants begin to flower, it is time to turn your legumes or plants into green manure.
3. Using a hoe or other material, chop, mow or cut the green manure plants at its base. We allow our cuttings to wilt for a few days.
4. Incorporate it into the soil by digging or by shallow cultivation. You can dig a trench 4 inches deep, 6 inches long and as wide as the bed size.
5. The time it will breakdown will vary from 6-8 weeks.

Green manure can be sown almost anytime but the best would be at the start of or the end of the rainy season. This is because you need a lot of water for the green manure to decay properly. The middle of the rainy season on the other hand is too wet and tilling the soil at this time might destroy your soil structure. We also do green manuring each time we start a new bed, to prepare an unused or exhausted soil for the next planting.