In the answer @bstpierre gave to this question on ammending soil he mentioned mixing layers of soil during double digging is a bad idea. I was wondering why is this?
I imagine mixing the layers at the initialization of a vegetable patch (converting from lawn to garden) would be a good thing. For example layering in the following way:
- compostable material + compost in the deepset layer
- turf and top layer of dirt
- mixed dirt
- more compost
- more dirt
might lead to a very rich, deep soil. Then, this procedure would only be repeated if the garden seems like it is depleted of nutrients.
At any rate, this is what I did last fall to prepare a new patch for the coming season. I dug down about 2.5' hoping that the turf and compostable stuff deep down would compost. I have a clay soil. I guess I can report back in a few months to say how it went, but it would be good to know what people have already experienced.