Wheat prices fell for the first day in five after the weather improved in growing regions of the Great Plains.
Brandon Marshall, an analyst at Northstar Commodity in Minneapolis, said the Plains states were getting more moisture, improving the outlook for the crops there.
Wheat for May delivery fell 18 cents, or 2.5 percent, to $7.025 a bushel. Wheat had fallen for four straight days before that.
May corn also fell, losing 5.25 cents to $7.0325 a bushel.
Soybeans were the outlier among agricultural commodities. The May contract rose 18.5 cents to $14.62 a bushel.
Prices for oil and key industrial metals fell Monday, as investors worried over U.S. spending cuts and a potential slowdown in China.
Palladium for June delivery fell $5.95 to $714.45 per ounce. April platinum fell $7.30 to $1,566.20 per ounce.
Benchmark oil for April delivery fell 56 cents to $90.12 a barrel in New York, a U-turn after two months of steep increases. The national average for a gallon of gas fell to $3.75 a gallon from $3.78 Friday. Brent crude, used to price many kinds of oil imported by U.S. refineries, fell 31 cents to $110.09 a barrel in London.
Prices for oil and industrial metals help reflect how investors feel about the economy. They're used in manufacturing, transportation and other activities that drive growth, so when their prices fall, it often means that investors expect the economy to slow down.
Investors had two main concerns Monday. The U.S. government is set to spend less money. Spending cuts of roughly $85 billion automatically kicked in on Friday after President Barack Obama and Congress failed to reach a compromise on some parts of the budget.
Also, the government of China, which has fueled the world economy even when other countries have stumbled, introduced new measures to try to rein in home prices.
The exception in energy commodities was natural gas, which gained 7 cents to $3.53 per 1,000 cubic feet. Other energy commodities fell. Wholesale gasoline fell 3 cents to $3.10 a gallon. Heating oil slipped 1 cent to $2.92 a gallon.
Gold, silver and copper were virtually flat. Gold for April delivery rose 10 cents to $1,572.40 per ounce. May silver edged up less than 1 cent to $28.496 per ounce. May copper inched up less than 1 cent to $3.5015 per pound.