Green manure
/ˌɡrin məˈnʊr/
Definition
Green manure refers to a cover crop grown mainly to be cut and turned into the soil while still green, rather than harvested. It is a soil-building technique, not a fertilizer product. Common green manure crops include legumes and grasses. As the fresh plant material decomposes, it adds organic matter, and legume species can also contribute nitrogen through bacteria associated with their roots.
Use in Gardening
- Soil organic matter: When worked into the soil or left as surface residue, green manure adds organic material that can improve structure, water infiltration, and moisture holding, especially in soils that are low in humus.
- Nitrogen from legumes: Legume species used as green manure can form root nodules with Rhizobium bacteria, which fix atmospheric nitrogen into forms that later become available as the plant breaks down.
- Nutrient capture between crops: Fast-growing cover species can take up leftover nutrients, particularly nitrogen, and reduce leaching during rainy periods. This helps keep nutrients in the root zone for the next planting.
- Weed and erosion management: Dense growth shades the soil surface, which can suppress many annual weeds. Root systems and surface cover also help protect bare ground from erosion and crusting.
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