I am planting a reclaimed strip-mine. I hope some day to end up with a food island there. Much of the level parts are back-filled with clay sub-soil. Its pretty spare of organic material. I am going to try a fall planting of winter radish as a green manure crop. if it works even a little, I'll keep trying it. I need something that can grow into this clay, and leave its mortal remains behind.
Any organic material will help your soil. If your county, city has tree trimmings they dump, it might be worth asking about. A friend had several dump trucks of shredded tree trimmings deposited by a tree service on their property for free. It took several years to break down but made a lovely soil on glacier till with time (it was a nature created gravel pit before).
I am sheet composting bark mulch where I have planted saplings. I expect that will need to continue for the rest of my life. I will keep on with green manure crops. I think I can speed up geologic speed.
