Soil improvement for clay?
I live here in the land of the red clay, in a subdivision where any topsoil has gone the way of the bulldozer. Lately I've been trying to think of ways to improve the clay soil that I'm stuck with in my 1/4 acre yard (I do have raised beds for vegetable gardening, but I have dreams of a lush backyard that could act as a small slice of heaven for the local wildlife). I've heard of laying down newspapers and growing cover crops, but can anyone describe either method in detail? I'd also like recommendations as to the best cover crops to grow to improve clay soil. Please note that since I live in a subdivision, I would like to try to avoid cover crops that could easily become invasive and spread to my neighbors' yards.