Compost is the lightest material on this site — around 1,000 to 1,300 pounds per cubic yard, roughly half the weight of topsoil. That makes it the one bulk order a half-ton pickup can genuinely handle a full yard of.
Thin layers do the work
One to two inches worked into the top of a bed is enough to change the soil meaningfully. For top-dressing a lawn, a quarter to half an inch is the right amount — spread it and rake it into the grass so blades still show through.
Compost is not a growing medium on its own. Filling a raised bed with pure compost holds too much water and runs out of structure as it breaks down. A common mix is one part compost to two or three parts topsoil.
Finished compost versus fresh
Finished compost is dark, crumbly and smells like forest floor. Unfinished compost still has recognizable material in it and will pull nitrogen out of your soil as it continues to decompose.
If a pile at the supplier is steaming, it is still working. That is fine for spreading in fall, ahead of winter, but not for planting into this week.
How often
Once a year is typical for beds, applied in spring or fall. Because compost breaks down into the soil rather than sitting on top of it, the volume genuinely disappears — unlike mulch, you are not building up layers over time.
Reading a compost test
Bulk compost from a municipal or commercial supplier usually comes with a test result, and two numbers on it are worth reading before it goes on a garden.
Soluble salts matter most. Compost made largely from manure can run high enough to damage seedlings, and it is the common cause of a bed that will not grow anything the first season.
Maturity or stability is the other. Immature compost keeps composting after you spread it, drawing nitrogen out of the soil as it goes, which is why an unfinished product can make a bed less fertile in the short term.
Where the volume goes
Compost loses volume after application in a way that mulch does not. It continues breaking down and it works into the soil, so a two inch layer in spring is visibly less by autumn.
That is the product doing what it is for, not a defect. But it means compost is an annual or biennial input rather than a one-time amendment, and the quantity should be planned that way.
Mixing into the top few inches rather than leaving it on the surface speeds the process. Left on top, it behaves partly as mulch and lasts longer.