A roundup of key agricultural commodity markets for the week of August 24-28 by Dow Jones Newswires in Barcelona

GRAINS & OILSEEDS: Macro conditions remained supportive of agricultural commodities, with a weaker U.S. dollar and sustained higher oil prices both supportive of prices in the sector.

U.S. PCE inflation data Wednesday, alongside Friday's Jackson Hole appearance by Fed Chair Kevin Warsh, will help determine the direction of the dollar this week, with investors watching for signals that the central bank would be open to raising rates.

Grains investors will watch developments in the Black Sea closely. Russia refused a truce that would halt attacks against ships carrying grains through the Black Sea, Ukrainian President Volodymyr Zelensky said Saturday, dimming hopes of a recovery in grain exports from the region. The deteriorating situation helped corn and wheat to trade at three-year and two-year highs, respectively.

Corn prices were also helped by last week's Pro Farmer Midwest Crop Tour, which showed that July heat had a greater impact on corn and wheat yields than previously expected.

The survey didn't help soybean prices, however, with Pro Farmer forecasting a healthier crop than the U.S. Department of Agriculture's previous estimates.

Weather risks will underpin soybean prices, Cory Bratland of AgMarket.net said in a note, with this year's record El Nino still to impact crop development. The impact of flooding in U.S. corn-growing regions remains a concern for farmers.

Speculative traders added to their bets that grain prices would rise last week, according to the Commodity Futures Trading Commission's weekly Commitments of Traders report.

Wheat futures rose 0.6% in Chicago to $7.03 a bushel in European afternoon trade Monday, while corn futures held near highs not seen since July 2023 at $5.19 a bushel, up 2.2% for the session. Soybean contracts fell 1.4% to $12.23 a bushel.

SOFT COMMODITIES: Coffee contracts jumped Monday, rising 5.7% to $3.41 a pound, as El Nino continues to concern market participants. Weather conditions in Vietnam, the world's largest producer of Robusta coffee, are in focus, Cocoa Intel's Georgi Uzunov wrote in a note. Heat in Mexico is also prompting supply concerns, coffee analyst Maja Wallengren said.

Trading volume in cocoa markets was extremely low last week, HCCO analysts said, adding to market volatility. New York cocoa contracts trade below recent highs, falling back under $6,000 a metric ton and down 0.35% for the session at $5,924 a ton.

Sugar contracts slipped 0.5% to 17.52 cents a pound.