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Argentine farm groups began a week-long strike on Friday and were already talking of extending their work stoppage beyond the scheduled Sept. 4 end date.

Some growers are demanding the strike be prolonged for another four days.

"Farmers are really fed-up about the lack of policies, the lack of solutions and the drought," says Pablo Orsolini, vice president of the Argentine Agrarian Federation, or FAA, one of the four farming associations that have led protests that erupted in March 2008 over a tax hike on soy shipments.

"There are proposals out there for the strike to be until Sept. 8. ... We'll be deciding this week to see whether to extend it until then or not," Orsolini told Reuters News Service.

Small groups of ranchers and growers gathered beside highways on Friday to stop trucks carrying grains and cattle from reaching market, but they were letting other traffic pass.

Grain trade was halted by the strike with no deals being done Friday in the main grain market of Rosario, traders say.

Farmers' decision to strike was triggered by President Cristina Fernandez’s veto earlier Tuesday of legislation granting export tax relief to farmers hit hardest by last season's drought.

Last week, Congress approved the emergency farm bill, providing at least 500 million pesos ($130 million) in drought relief funds. The bill provided tax benefits and suspended export taxes for farmers from districts declared "disaster zones" and cut the export taxes in half for farmers from "emergency zones."

Farmers will still receive the aid funding, but the president used her line-item-veto powers to strike the tax breaks from the bill.

Fernandez’s veto further provoked farmers who were already angry over last week’s congressional vote to extend Fernandez’s power to set export taxes for another year. Farmers had hoped for a victory there after a midterm election on June 28 in which Fernandez lose her majority in both chambers in Congress.

Editor’s note: Richard Brock, Corn & Soybean Digest's marketing editor, is president of Brock Associates, a farm market advisory firm, and publisher of The Brock Report.