So I've dug these 4' deep by 5' diameter pits in order to put soil into my
potato tire towers. A kind friend gave me a load of reasonably dry horse
manure, which nicely filled the pits back up to grade level. What do I do
with this stuff now? Keep it moist so it will rot? Cover it with dirt? Put
wood shavings on top? Buy some worms and let'em loose? The surrounding soil,
by the way, is compacted sand - it drains well, but is stable enough to
maintain a vertical hole as deep as I care to dig...

Thanks in advance for any suggestions.
Dick Lovering