NEW YORK—Commodities mostly fell Tuesday as oil skidded lower and corn dropped below $6 a bushel, suggesting the commodities boom may be losing momentum as the slowing world economy saps demand for energy and raw materials.

Crude oil shed more than $4 a barrel during the trading day, dragging down everything from gold and silver to corn and heating oil in the latest in a string of recent commodities sell-offs.

Experts say a host of factors are behind the pullback. Record high energy prices reached earlier this summer are starting to crimp global economic growth, leading...