Green manures are often used on bare soil to help smother weeds and help lock in the nutrients. They are then dug into the ground in spring releasing the nutrients back into the soil and also help improve the soil structure.
Green manures are usually sown in late summer or early autumn either by sowing them in rows or broadcasting them and then raking the seeds into the soil. When you need to use the ground again, simply dig in the plants and leave to rot. It is recommended you leave it at least two weeks before planting into the soil to allow the green manure to rot down.
A good winter green manure to use is Grazing Rye (Secale cereale). This is a good overwinter plant that will improve the soil structure, and can be sown between August to November and then dug into the ground in spring.
If you’ve got eelworm, you can use Mustard (Sinapis alba). It can help curb your eelworm problem and is an excellent green manure to use after potatoes. However be careful, it is a member of the brassica family and could encourage clubroot. Sow between March and September and leave it 2-3 months before digging in.