"Bob Hobden" wrote
"Phil L" wrote
..and didn't get a definitive answer, so I'm asking again.
I have noticed in farmers fields, huge piles of what appears to be a
blueish/greyish stone, I work in the construction industry and to me
it looks like MOT, or crush & run, but blue.
Upon closer inspection (IE picking it up) it has no odour, feels like
soft stone and the 'stones' range from 3 inch down to grit.
snip

Dried treated sewage solids perhaps?

Which they euphemistically call "bio-solids" for a better marketing
image. ;-)

It's used around here on agricultural land. My Other Half reckons it has
a distinctive, but not particularly bad, smell - "If it was over that
hedge you'd know it was there". Phil's mystery stuff was odourless but
perhaps different treatment processes make a more deodorised end
product.
--
Sue