GRAINS-Chicago wheat falls on harvest pressure; corn hits contract lows

By Heather Schlitz

CHICAGO, June 24 (Reuters) - Chicago wheat futures sank on Tuesday on pressure from the ongoing harvest in the U.S. Plains and Black Sea as well as a lack of weather threats, analysts said.

Front-month corn contracts hit lifetime lows on expectations of ample corn stockpiles, and soy fell on weakness in soyoil and crude oil futures.

Oil prices tumbled on Tuesday after President Donald Trump said a ceasefire has been reached between Iran and Israel, though he later accused both sides of violating the accord. Continued tensions between Iran and Israel are expected to add volatility to the market.

"The wild card is the geopolitical situation," Brian Basting, analyst at Advance Trading, said. "It's a recipe for volatility."

The most active soybean contract Sv1 was last down 9-1/4 cents at $10.52-3/4 per bushel as of 12 p.m. CDT (1700 GMT). Soybean byproduct soyoil BOv1, widely used in biofuel, was down 1.32 cents per pound as it tracked falling crude oil futures.

CBOT corn Cv1 eased 1-1/2 cents to $4.18 per bushel, after earlier setting a contract low at $4.16-1/4 a bushel. CBOT wheat Wv1 fell 15-1/2 cents to $5.54 a bushel.

Grain markets remained under pressure from expectations of ample U.S. and global supply, despite weaker-than-anticipated weekly U.S. crop ratings.

Analysts expect hot weather and rains forecast in the week ahead to support crop growth in the U.S. Corn Belt by creating a greenhouse-like effect.

Dry weather in the U.S. Plains has helped the winter wheat crop dry down after drenching rains in previous weeks, and experts predict the wheat harvest will accelerate this week.

Broadly favorable production prospects for wheat across the Northern Hemisphere were also weighing on the market as harvesting got going.

Argus Media has increased its forecast for Russia's 2025/26 wheat production, now projecting output to reach 84.8 million tons and come in well above last year's 81.3 million tons.