Green Manures: What are they and why should you use them?

With more and more people moving away from the use of animal products, green manures are becoming increasingly popular. They are cheap and easy to grow and they remove the chore of sourcing and moving animal manure around your plots!

Alot lot of people love to use animal manures but it can be difficult to source organic animal manure. We need to consider how the animal was raised and how this could affect our overall organic mission. For anyone who sources animal manure this should be at the forefront of their minds.

Green manures are plants that are grown for their nutrient value and their ability to improve and feed the soil. They are often used as a cover crop so that soil is not left bare. A bare soil will quickly loose moisture and valuable nutrients.

Once they have grown, the foliage is chopped down and left to decompose which increases the organic matter in the soil. The higher the content of organic matter in our soils, the better they are able to hold onto moisture and vital nutrients. This benefits both the soil life and the next crop. A soil that can retain moisture will also help us gardeners on those hot days when watering quickly becomes a chore.

Green Manures provide habitats and food for pollinators and other beneficial insects and also provide both food and habitat for our living soil organisms. By encouraging more pollinators and beneficial insects into our gardens we can create and build our own self-sustaining eco systems to help us fight pests in a natural way.

There are many different types of green manures available. There are some that should be used as part of your crop rotation and some that are not as fussy. To increase nutrient diversity, you should try and mix multiple varieties together.

It may surprise you that green manures can be used in a no-dig system. Many people are under the impression that they need to be dug into the soil. 

In a no dig system the goal is to disturb the soil as little as possible so as not to damage the soil life (or disturb the weed seeds!). Additionally, the less we disturb the soil, the more carbon is stored and not released into the atmosphere.

In a no dig system you should be use green manures with soft stems and foliage such as phacelia and buckwheat. They will be a lot easier to cut down and it will be quicker and easier to incorporate these into the soil. Avoid rye in a no dig system as, like any grass, they can be extremely difficult to remove.

Green manures should be cut back before flowering. If they flower, the stems will become much tougher and woodier and they be much harder to incorporate.

In a no dig system the ideal green manure varieties are ones that you can ‘top and chop’. The foliage will break down much quicker if you chop it up when you top the plants. You can also add a layer of compost on top of the mulch to help suppress regrowth.

For a longer-term solution, we can use things like white or red clovers. White clovers make a lovely ‘living’ mulch. They are perfect for under planting under soft fruit bushes as they are low growing. They will also help keep the other weeds down!

Red clover is also a good long-term solution. The foliage can be chopped multiple times in a season and used as a mulch.

Green Manures really are a fantastic way to keep your soil alive and healthy in a plant-based way. They also encourage pollinators and other beneficial insects to your garden.

Happy Sowing!