SINGAPORE - Chicago corn futures lost more ground on Tuesday, dropping to their lowest in almost a week as improved U.S. crop ratings and expectations of more beneficial weather pressured prices.

Wheat fell, while soybeans were largely unchanged.

"U.S. corn crop is in good shape as the weather has been pretty favourable," said one agricultural broker. "Expectations of bumper production from the U.S. are going to keep pressure on prices."

The most-active corn contract on the Chicago Board of Trade (CBOT) fell 0.2% to $4.20 a bushel as of 0252 GMT, have dropped to its lowest since July 2 at $4.19 a bushel.

Soybeans added 0.2% to $10.23 a bushel and wheat slid 0.5% to $5.46 a bushel.

The U.S. Department of Agriculture (USDA) said after trading ended that 74% of the nation's corn crop was in good or excellent condition, up one percentage point from a week earlier.

Rains have benefited the U.S. Plains and western Midwest, and boosted soil moisture in Iowa, according to weather firm Vaisala.

Temperatures will be near normal in most areas this week, the firm said, favouring the corn crop during the critical pollination period of development.

Farmers in Brazil's center-south had harvested 28% of their 2025 second corn crop as of last Thursday, agribusiness consultancy AgRural said on Monday, up 10 percentage points from the previous week but well below the 63% reported a year earlier.

Large speculators increased their net short position in CBOT corn futures in the week to July 1, regulatory data released on Monday showed.

The Commodity Futures Trading Commission's weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, trimmed their net short position in CBOT wheat and increased their net short position in soybeans.