In article , "Snag"
wrote:

For one thing , I want to plant something as "green mulch"
this fall to be tilled in to help increase the organic content of this soil

If looking around for ideas, "green manure" is the more common term.

I personally favor things that will winter-kill - does mean it has to go
in early enough to get established and grow before it's killed, but it
also means it's not coming back from the dead in spring when you try to
till it in. Builds some fertility, and holds soil through the winter so
you don't lose it. Some things that will grow through winter might be
less prone to coming back when plowed/tilled - check with the extension
agent or other local growers for ideas to suit your climate. If you can
give a section of garden (or "a part of your rotation") over to growing
green manure through the growing season, your options increase.

If you have a truck or trailer, also keep an eye out for horse people,
and brown manure. Most of them don't have a spreading plan, so they get
piles. Best bet is to re-pile at your place and see what the weed
content is like, while giving the pile a few turns (inside to outside,
outside to inside) to try and do in the weeds. If the pile is uphill of
the garden, so much the better (runoff/leachate gets into the garden.)
Then spread it. If you get on a regular collection run, it is a far
faster way to build fertility than green manuring.

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