We are continuing to add layer upon layer of organic materials to our garden space: leaves of any and all varieties that I can get my hands on, sawdust from the local woodworker's shop, ground up vegetables left over from the organic farms here in the neighbourhood (probably 200-300 pounds a week), in addition to chicken manure from my free ranging hens. When we established the vegetable garden 3 years ago, it was on heavily compacted clay that had been a horse corral. We tilled in a high dose organic fertilizer, lime, oyster shell, and ground fish meal one time. Since then, we have been building up the soil on top of that base by composting in place, without using a tiller on it again. This past spring, we finally we had earthworms! Our vegetable garden space is roughly 100' x 100' or 1/4 acre.