According to the US Geological Survey report on peat:
the average density of different types of peat varied over a considerable range.
Table 6 of the report is titled, aptly, "AVERAGE DENSITY OF DOMESTIC
PEAT SOLD IN 1999"
and tells us the density (in kg/cu meter) of:
sphangnum moss 169-219
hypnum moss 475-578
The table also tells us:
To convert kilograms per cubic meter to pounds per cubic yard multiply by 1.685.
Accordingly, the above table, in pounds per cubic yard is:
phangnum moss 285-369
hypnum moss 475-800
So, the number of cubic yards in a ton (2000 pounds) of peat comes to:
phangnum moss 285-369 7.0-5.4
hypnum moss 475-800 4.2-2.5
reed-sedge 939-1006 2.1-2.0
Humus 1342-1778 1.5-1.1
So it seems your guess was awfully good as far as humus is concerned,
but other forms of peat, being far less dense, need a lot more cubic
yards to make up a ton of the stuff. No doubt, the water content of
the peat types is a big factor in the weight difference.
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