Good points Tris and Pete Budd is indeed the man.
Last night I met a successful farmer who builds soil with green manures only, but he uses a rotovator set shallow, on wheels, to chop them up and roots too, at a depth of max. 2in (5cm).
The trickiest part is always killing them to prepare ground for sowing/planting.
This man finds slugs are not a problem, I am intrigued by that, and he is biodynamic which perhaps helps.
