I disagree. Bushel is a measure of volume. In that volume you can put corn, wheat, chicken feathers or ball bearings.

Now, the trade definition of a "bushel" of corn has been fixed at 56 pounds, soybeans at 60, and so on. For that reason only does bulk density (test weight) matter.

But a bushel is still a bushel...or four pecks or 2150.42 cu in.