I posted my first reply without reading the whole tread, than I read it. So I will try to answer some of you questions. Maybe it does need to go in separate thread.
Tilling and digging is the same thing just done by different tools.
Mulching is always good even if you till. mulching helps to preserve moisture in the soil.
Sheet mulching/sheet composting/lasagna gardening all refer to putting layers of organic material on top of existing soil to improve it without digging. I would not garden in any other way. I get my organic materials from neigbors and other neighborhoods on trash days and I was able to start and plant a flower bed 30x12 feet for $150 where most of the money went to buy plants. While my other beds (conventional started before I knew about the method) suffered with heat and drought in our South summer this one was lush and green and blumed through the summer without any extra watering that other beds did not recieve.
You can absolutely do no dig/sheet mulching in walled raised beds. It would take several seasons for your mulch to turn into nice soil and build up to full hight but if you work on adding organic material in between growing seasons you will fill in you beds without bringing soil from some where else. Would you like to avoid bringing soil in or to have structured beds?
In biointensive method beds are slightly raised because the soil is fluffened. However double digging works well only if your soil is improved. For clay soil it would mean that you need to bring loads and loads of organic material (compost) and mix it in to you soil. Just double digging you clay soil would not improve it enough to make a differnece for plants.
If you do not like to have structured raised beds you can simply do your layering on the ground but it may prove difficult to keep edges of the bed neat and weads from growing into you beds.
I have both structured and just plain raised beds and I have been working on converting all of my vegetable beds into structured beds because they are neater and need less upkeep. My flower beds are going to stay the way they because I like the organic shapes for them.
The most succesfull ones that I started from scratch were done by building a rectungle 4 feet wide and 12 feet long and 12 inches wide. The ractangle can be any lengh but 4 ft width allows you comfortably work on your bed from both sides and the higher the bed the more soil it can accomodate. Than I put a layer of cardboard and on top of it started putting horse manure, grass clippings, fallen leaves adding layers as matterial were becoming available to me. I put compost almost between each layer. It took several months to build it up. Then it was time to start planting I would just make a hole, fill it in with good soil/compost and put my seedling in. Usually bu the end of growing season all of the layers are decomposted and I add new layers. Overtime you beds can get preatty high.
Originally Posted by onetrumpeter
so... mulch? or double dig? or till? sheet mulch? you can do that with a raised bed? and what exactly IS a raised bed? I used to think it was walled and filled with brought-in-soil (want to avoid that) but in Biointensive it seems they mean soil that's been double dug and thus aerated and raised somewhat. thanks for letting me process what I'm reading here ;) and any thoughts are much appreciated!