i recently finished a rock wall that i've been working on; it's drywall construction, built up out of lava rocks .... the rocks limn a slope and, when the rocks had settled in place i filled the declivity behind them with potting soil, soil amendment to break up the clay underneath it, and compost from my compost heap .... oh, don't go thinking that i'm some kind of organo freak; i spray my roses: the only reason i compost now is that the compost container was a wedding present ....
think about that: a compost heap for a wedding present!