40 tons of compost an acre is how many iches deep?

Answer 1

The answer will depend on the density of the compost. For this question, I am going to use 800 pounds/cubic yard (see: http://www.dot.ca.gov/hq/LandArch/policy/compost_specs.htm)

40 tons=80000 pounds

Volume=Mass/Density

80000 lbs/(800lbs/cu yd)=100 cubic yards

So we have 100 cubic yards of compost spread over one acre.

One acre is 43560 square feet = 43560/9=4840 square yards.

Volume = Surface area*depth

100=4840*depth --> depth=(100/4840) yards

Now convert depth to inches by multiplying by 36 (since there are 36 inches in a yard).

(100/4840) yards=(100/4840)*36 inches=90/121 inches, or about 3/4"