Green manures are a range of seeds that are sown specifically to improve or assist with soil fertility and/ or the conditioning of soil. They are not harvested for food, and are not allowed to flower. Depending on the species they either “lift” any surplus nitrogen that is in the soil and hold it there within the host plant i.e. - which would otherwise be lost through drainage, until the host material is incorporated back into the soil or they “fix “the nitrogen by taking up the nitrogen from the air and holding it in nodules that grow on the host plant's roots and are released when the host plant is incorporated back into the soil.
The main benefit of growing Green Manure is its' ability to fix or lift nitrogen into your soil. Why is this good?
Nitrogen Defiency results in stunted / slow growth – this often occurs when the soil has been heavily used to grow crops. Recent studies has shown that overall there has been a fall in soil fertility. This natural crop can only benefit your garden or allotment!
There are certain types which hold nitrates in your soil for current crops to use and others which take nitrogen from the atmosphere and stores it in their roots for digging in for subsequent crops.
See the How to Grow Green Manure section to see which you should grow. It's so easy to do!