PARIS/SINGAPORE: Chicago corn and soybeans fell on Thursday as the market took a breather after concern over dry weather in South America and export disruption in Argentina pushed prices to their highest in more than six years.

Wheat lost ground for a second session as it also eased back from a six-year peak earlier in the week.

A bounce in the dollar after two-year lows against other major currencies encouraged grains to consolidate while traders awaited weekly US export data later on Thursday and a monthly world crop report from the US government next week.

The most-active corn contract on the Chicago Board of Trade (CBOT) was down 0.7% at $4.91-3/4 a bushel by 1221 GMT.

The contract reached its highest since May 2014 at $5.02-3/4 on Wednesday, but faced chart resistance at the $5 threshold.

CBOT soybeans inched down half a cent to $13.61 a bushel, after striking their highest since June 2014 in the previous session at $13.78-1/4.

Wheat gave up 0.9% to $6.41-3/4 a bushel, slipping further from Tuesday's six-year high of $6.64-1/2.

"The upswing in grain and oilseed prices has come to a halt for the time being, probably partly because the US dollar has been firmer since yesterday," Commerzbank said in a note.

"Nonetheless, all the prices are still not far off the six-year highs."

Dry weather continues to threaten soybean and corn yield prospects in Argentina and part of Brazil, while labour disputes and a government suspension of corn exports have disrupted grain shipments from Argentina.

The soybean market has shifted to "rationing mode" as tight global supplies and crop-stressing drought in Argentina have ignited the strongest soy market rally in years, Joe Stone, agricultural supply chain head at agribusiness group Cargill, said on Wednesday.

Grain markets have been sensitive to any risks over South American supply as strong Chinese import demand has already absorbed much available soy and corn on the world market.