Green Manure has been covered on here in depth before. Charles renamed an extensive thread Green Manure because of the amount of interest but I don`t know how to find it. I started an experiment to grow veg sustainably i.e. no imported fertilisers inc manure to avoid importing pests and/diseases, it worked very well on an allotment I had for 25 years. 5 years ago I took an allotment on a new site which needed a boost to get it going, (I used pig manure). My green manure consists mainly of comfrey, lucerne and grazing rye. Comfrey is a permanent bed, grazing rye is winter cover and I am leaving my beds of lucerne for 2 years at the moment because the subsoil is very compacted and lucerne is very deep rooted. I dont dig my green manure crops in, neither do I dig them out. Comfrey can be used fresh as a nitrogen boost, as an activator or made into a liquid feed. Grazing rye is cut to ground level when fully grown and composted, the roots soon disappear. Lucerne is cropped 2 or 3 times a year and added to compost, when it has to come out I chop it below ground level, (call it digging if you like but its minimal disturbance). Lucerne is very interesting because the roots decompose in the ground and brassicas seem to do well when following it. I could go on but I think thats enough for now.
Cheers
Pete Budd