Cover crops in zone 4, no machinery

I was wondering if anyone knows what cover crops work the best in zone 4. I am practicing a no till concept to help correct a slight hard pan issue. I plan to use diakon radishes, but would like to use oats too. For I hear both are great for a tillage cover crop, plus add some bio mass. I'm pretty sure most cover crops will do well where I am at, but I just don't have much of an actual plan. I have things I want to do and like to do, but I'm not sure how to go about it quite yet. I don't have any farm equipment, but wish to cover crop about 2+ acres of garden space. Winter killing seems to be my best option for now. Are there other ways to kill that require no machinery? Also do I have to kill back all types of cover crop. Are there good green manure perennials that can be used for instance? What is an easy and great green manure crop that could be grown in place? Can growing a living mulch work in a vegetable garden(I'm new to this idea a bit)? I could use a planning template if there is such a thing. What do you permaculurists think?

-Matt

Hi Matt:
I have been asked to start answering your question. Though I am in a warmer maritime climate. Certain questions need to be answered first. What is growing there now? How do you plan to get the seed in contact with the soil and get ahead of the competition of undesirable plants? Machinery is not necessary but what tools do you have or plan to get?
This is the tool I recommend Broadfork by Medow creature it will solve the compacte layer problem.

If you need to kill down tough weeds Like quack grass try my carpet garden method. Previous answer on permies where you can also see what I have been doing on my farm.

This is old and late but oats will winter kill at zone 6 and lower.
Tillage radishes will winterkill and leave largevhilrs in the soil for water and air as well as adding some pathways for worms. When combined with peas, you will get some nitrogen through the nodes on the peas if the peas or inoculated or if peas have been grown recently.
Sudan grass or sorghum will put on tremendous growth in the warm summer but will easily winterkill at the first frost. Some Sudan grass I had on an acre this year was higher than the muffler of my general purpose JD 630 when I mowed it .
When you think about integrating a cover crop or green manure, you also have to think about the incorporating any debris left next year.  In areas where I am going to grow a garden crop, I like radishes

The best cover crops for your area would be daikon, winter oats, winter rye, winter wheat, yellow, red, crimson clovers will do well too.
These can also be planted in the early spring and they will do a good job of sprouting as the weather begins to warm up.