I use lettuce year-round in zone 8. I put it under squash and corn to keep down weeds. When they are about to go to seed, I just pull them up and let them lay on top of the soil as mulch to retain moisture as summer heats up in August. I use them as attractive borders where I can't weed easily, and they are great at keeping out weeds. In the fall, I grow a crop for food and extra to throw into the compost. It breaks down so quickly, so I can use the compost in February, when I am ready to plant early spring crops. I also really like sweet peas for the high nitrogen and fast decomposition. Another poster mentioned radish seeds for cover crops. I needed to break up hard soil, so I threw in some daikon radish seeds. They did an amazing job. Root vegetables are a great cover if you are interested in no-till gardening. Just keep topping with compost and let the roots and worms do their job!

I would agree with borderbarb that there's probably not enough surface area to grow a lot of green manure but it's sounds like something I might try for the heck of it. Right now I have sunflowers and sweet peas growing out of compost covered hay bales. To what end I'm not entirely sure but they should look cool if they take off. I think if you want to grow your greens for your pile you're probably better off setting aside a section of your garden for it. Comfrey is supposed to be excellent for that but it is invasive. I have enough invasive plants growing already so I've kept away from comfrey. I'm growing some borage this year and that is supposedly a good green for the compost pile. Are you sure you can't scrounge up some greens? A quick search of Cleveland's craiglist showed a handful of people getting rid of hay which is usually a pretty good green in the compost pile. It helps having a pickup truck to get those sort of things.

I was leaving the posting to those with a more appropriate climate but... I mainly grow daikon to eat (makes great pickles and kimchee), but it grows like mad and I always end up watching some get pretty huge. I'm in sandy soil, so breaking it up isn't an issue, but they certainly would! In temperate climates like mine, it's generally recommended to chop large roots off at ground-level and leave to rot in the ground. I presume in your climate you just let the cold do the work! My only concern would be a brassica cover-crop mucking up rotation. I don't rotate as my garden's tiny, but it could be worth factoring in.

Soybeans must be SUPERCOMPETITIVE. I can hardly believe anything could hold its own against the roots I see on my bred-for-the-south okra. I think it could even give cotton a run for its money... (Hmmm, that would be interesting to try... they're even kinfolk!) Cotton is infamous for its ability to take every last bit of moisture... and nutrients!!!... from the soil. Variety differences could also account for some of it. One okra I planted this year was a hybrid bred for the north (I bought it for its earliness and sent seeds to my siblings in Denver and SE Wyoming, so I figgered I should try it, too). It was fine til the weather got really hot and dry, then it was the first to wimp out. My brother in Wyoming, with unlimited water cuz he's the ranch foreman and his provided house is on the same meter as the stock tanks, used almost daily drip irrigation on it and was thrilled with his results. My sister in Denver...not even a strongly wannabe gardener... planted it in most-of-day shade. Far as I know she's still waiting for her first pod.... I can't use a shovel in my ground... too many rocks. I have 2.5 pound maddock picks mounted on 2 handle lengths, plus a few smaller diggers, and I use yardsale rollerbladers' knee guards to kneel with when I plant stuff that requires going to ground. I dig roots cuz that's how I get old plants out of way for the next crop, plus I guess I have just learned that powerful root systems mean success or failue here in this extreme climate and rocky clay soil. Also, where I do not cultivate except by earthworms, pulling out plants by the roots (and hand weeding) is a cultivation, of sorts. Hoes don't work very well on my ground, either. I have a pix... intended as humor mostly but it's the facts... which is my tool kit for Ozark gardeners. I'll post it and do a link below.... Dreadful to hear what happened to Heritage Farm's crops! When I watched weather reports all this spring and summer, my heart would just sink thinking about what it was doing to gardeners all over the country. The endless rain in Texas and all the way north from there would have just rotted seeds and plants. A garden underwater will never happen to me on my hilltop, but a 6-inch rain is quite a mess until it finishes draining away. I can barely imagine what week after week of it would mean... or maybe I CAN imagine it! We had a spring of uncommonly warm 3 weeks early, then a once-in-100-years hard freeze in mid-April (ie, all fruit trees and wild oaks already bloomed, strawberries brought into premature bloom, corn 6 inches high, most people's tomatoes and squash already up and growing) It was devastating... tomato plants actually became scarce around here for a short time... until Walmart via Bonnie's consignment hybrids filled the void. After the freeze, it rained just enough each day to keep foliage wet... and my generally dependable Brandywines and PA Amish / Mennonite / Upper Midwest varieties went down like 18th Century European soilders marching headfirst against cannon fire. This became a bit of an embarrassment to me. I had decided to go all fresh seed this year, so I grew off for transplants my left-over 2004 seeds of red and yellow heirlooms and gave them away to senior citizens, many of whom I have to face once a month. They had a lot of crop failures from foliage diseases, and most of them ain't that knowledgeable as gardeners, so they are acting like I lied about the plants' potentials! Anyway, back to my garden results. Only one open-pollinated tomato did not get BER. It was a variety bred for New Orleans! Unfortunately, it also turned out to be determinate, and last week the deer ate 100% of the mature green & ripening tomatoes off my sucker-started clones of it for fall tomatoes... no seed crop! Next came 2 months of drought, the last month of it with record triple-digit temps for a whole month. The survivors of the foliage diseases now began to produce quality tomatoes... til the heat felled a few more... and now there are 3 staked tomatoes still standing, plus a wildcard I bought mostly for its name but with low expectations because of its north Europe origins... Blondkopfchen from Germany!! Also had one red almost-cherry hang in there, and of course Matt's Wild Cherry from Mexico, but do you consider that a tomato? I think of it as a semi-wild berry. Beans as ripened seed on the vine are nearly impossible for me ... I take in very mature pods still leathery and let them finish inside. Heat + humidity doesn't dry off bean pods very well. I had some Christmas limas dry off on the vines, and in several of them the seeds actually sprouted before they dried!! Usually the problem is molds.... Oops, almost sunrise... I gotta finish and get out to see what deer and armadillos did last night, and be a "presence" while Chuckie McVarmit is figgering out where to have breakfast. Here is a link that might be useful: Tool kit for Ozark Gardeners