Meri - quite a feat to tear down that shed. Kudos to you! In all honesty, it's a guess at this time as to what the soil needs. Can you get a soil test done? Perhaps there are other contaminants in the soil that have gone unnoticed? If there was coal stored there, could there be excess potassium in the soil? What might some of the other "junk" stored in the shed consist of? I think too many questions remain to be able to recommend specific amendments.
