NEW YORK—Commodities fell sharply for a second day Tuesday after another big drop in crude prices suggested that a global economic slowdown is curbing the world’s thirst for for energy and raw materials.

Gold, silver, copper, corn and most other agriculture futures sank as crude tumbled nearly $6 a barrel, bringing oil prices down almost $10 this week. A stronger dollar also rendered commodities more expensive to overseas buyers, curbing some demand.

After a year of explosive growth in the commodities sector, analysts say signs are emerging that the boom may be slowing ...