What is green manure?
Written by Daily Fix - Published 29-Jul-2022, last updated 03-Jan-2024
Gardeners use the term 'green manure' when referring to plants grown to cover bare soil which are then dug back into the soil to improve soil fertility and soil structure.
As the plants cover the bare soil they also help to suppress weeds which results in less weeding.
How to use green manure in the garden
Plant green manure in rows, or broadcast across the soil for complete coverage of the area - lightly rake the seeds into the soil and, if it's dry, water in.
Once the plot is needed for sowing new crops, chop down the foliage of the green manure and leave it to wilt.
Dig the plants and foliage into the top 25cm (10in) of soil.
It's as simple as that!
Benefits of using green manure
When most people think of manure, they think of the brown kind that comes from cows, horses, and other farm animals. However, there is also a green kind of manure that is made from plants. This type of manure is often called green manure, and it has many benefits for gardeners.
Green manure can be used as a soil improver
Green manure can improve the soil in a number of ways. For example, it can help to loosen the soil and make it more fertile. It can also help to break up clay soils and promote better drainage. In addition, green manure can add nutrients to the soil, such as nitrogen, phosphorus, and potassium. This can be helpful for plants because these nutrients are essential for their growth.
Green manure can protect against soil erosion
Another benefit of using green manure in the garden is that it helps to protect against soil erosion.
Using green manure to suppress weeds
Green manure crops grow quickly and their very leafy growth can outcompete weeds, smothering them before they can take hold. Green manure acts as a living mulch, suppressing weeds and retaining moisture in the soil.
Green manure can help with pest control
Green manure can provide a great habitat for frogs, beetles and other natural predators that like the damp cover of green manures. These residents will feed on pests such as snails and slugs - natural pest control in your garden.
Credit: Photo by James Frid, Pexels
Is green manure good for clay soil?
Clay soil can be a challenge to work with, but adding green manure can help to improve its quality. Clay soil is usually very fertile, but it can benefit from opening up the structure so that plant roots can get in there and access the nutrients.
Green manure is made up of plant material that is left to decompose, and as it does, it adds nutrients and organic matter to the soil. This can help to improve drainage in clay soil and make it easier for plants to take up water and nutrients in future growing seasons.
What is the best green manure for clay soil?
If your garden has clay soil, field beans, lupins and grazing ryes have deep roots that will break up the soil. Let the plants do the digging for you!
Hungarian grazing rye locks nitrogen into the soil, has deep roots that break up clay soil and looks lovely in winter. Just be sure to wait two weeks after digging in in spring before you sow. This is because a seed germination inhibitor is released as the Hungarian grazing rye breaks down.
Types of green manure
There are many different types of green manure plants that you can use in your garden, including clover, alfalfa, legumes, vetch, and rye grass.
When to plant green manure
Green manure can be added to your garden at any time of year, but it is best to add it in latest summer or early autumn after you have harvested your vegetables, when there is plenty of time for it to decompose before planting new crops.
It can also be planted approaching winter for digging in the following spring.
Conclusion: Should you use green manure?
In conclusion, green manure is a great way to improve your garden soil. It is a natural way to add nutrients and organic matter to the soil, which helps to improve the health of your plants. Green manure can also help to suppress weeds and pests, and it is a great way to improve the overall fertility of your garden.
So if you are looking for a way to improve your garden soil, green manure is definitely worth considering.
Happy gardening!
FAQs
It's best to wait for a few weeks after incorporating green manure before planting vegetables to allow sufficient time for decomposition and nutrient release into the soil.
The decomposition time depends on various factors but typically ranges from a few weeks to a couple of months.
Once the green manure crop has reached maturity but not yet flowered or set seed, it can be cut down and then tilled into the soil.
Yes, certain grasses like rye, oats, and barley can be used as green manure to protect the soil from wind erosion and add organic matter when tilled under.
Leguminous green manure includes plants such as clover, alfalfa, soybeans, and vetch.
Legumes like clover and vetch are excellent choices for clay soil as they fix nitrogen in the soil while adding organic matter. Other options include buckwheat, ryegrass, and mustard greens.
Green manure helps break up compacted clay soil by improving its structure and drainage. It also adds organic matter, nutrients, and beneficial microorganisms to enhance soil health.