A roundup of key agricultural commodity markets for the week of September 8-11 by Dow Jones Newswires in Barcelona

GRAINS & OILSEEDS: Investors will keep a close eye on developments in the Black Sea, where significant escalation in attacks between Russia and Ukraine have sharply curtailed exports from crucial grain-growing regions.

In an address Friday, President Volodymyr Zelensky said diplomatic talks are continuing to establish safe food transportation through the Black Sea. U.S. envoys Jared Kushner and Steve Witkoff visited both Kyiv and Moscow over the weekend in a bid to reenergize peace negotiations.

However, talks ended without signs of progress toward a deal to ease attacks in the region.

U.S. inflation data will also help shape the outlook for grains. A hotter-than-expected personal consumer price inflation print on Friday would heighten expectations of a Federal Reserve rate hike, in turn weighing on agricultural commodities.

Friday will also see the release of the U.S. Department of Agriculture's World Agricultural Supply and Demand Estimates. The report will give investors "a more concrete read on U.S. production and potentially setting the tone for the rest of harvest," Peak Trading Research analysts wrote.

Speculative traders bought into grains at their highest volumes since March, according to the Commodity Futures Trading Commission's weekly Commitments of Traders report.

"Agriculture positioning looks increasingly crowded," Saxo's Ole Hansen wrote, raising the risk of a swift downturn in prices if investors look to exit their positions at the same time.

Hotter weather across U.S. grain-growing regions could hurt crops nearing harvest.

Wheat futures jumped by 21% in Chicago to $7.49 a bushel in European afternoon trade Tuesday, while corn futures rose 0.5% to $5.395 a bushel following the failure of weekend talks to reopen the Black Sea. Soybean futures were flat at $13.10 a bushel.

SOFT COMMODITIES: Concerns around West Africa's cocoa crop drove prices higher last week, as the intensifying EL Nino weather system provoked concern over supplies from the region. New York cocoa contracts slipped 1.6% to $6,091 a metric ton Tuesday.

"Tighter forward supply expectations outweighed evidence of improving current supplies," Rabobank analysts wrote in a research note.

For the week ahead, weather forecasts point to rainfall across cocoa-growing regions in Ghana and Ivory Coast, easing drought risk, CocoaIntel's Georgi Uzunov said.

Coffee contracts slipped as the Brazilian harvest neared completion, encouraging global supply outlook, the analysts from Rabobank said.

Coffee futures slipped 1.2% to $2.92 a pound in New York Tuesday, while sugar contracts slipped 0.1% to 18.05 cents a pound, holding close to one-year highs.

Agricultural commodities remain vulnerable to a sharp downturn given the high concentration of investors betting on the sector to rise, Saxo's Hansen wrote.

"Strong buying extended into a fourth consecutive week and increasingly raises the question of whether positioning has become vulnerable to a pullback," Hansen said.