Farmers in Argentina are launching a seven-day strike to protest against the government's agricultural policies.
They will halt sales of grain, oilseeds and cattle after the government refused to lower export taxes on soya beans - the country's main crop.
Farmers are also angered by what they say is a weak cabinet response to a recent devastating drought.
Argentina has been hit hard by the global downturn as demand plummets for exports of soy, beef and grain.
Last year, farmers withheld their harvests and blocked roads for four months when the government announced plans to increase export taxes on key crops to raise revenues.
That strike caused food shortages in the capital Buenos Aires and other areas.
'Opportunity lost'
At a news conference in Buenos Aires, farmers' union leader Mario Llambias announced that the seven-day strike would begin from 0300 GMT on Saturday.
Ahead of the industrial action, farmers blocked major roads around the country.
They are protesting against a recent decision by President Cristina Fernandez de Kirchner to channel export taxes on soya beans into an emergency fund for the country's provinces, instead of reducing the levy to help sales.
"A great opportunity was lost," Mr Llambias said.
However, he said the unions, representing more than 200,000 farmers, wanted to keep talking to Mrs Fernandez's administration to try to find a compromise.
Argentina is a major producer of soya beans, corn, wheat and beef.
But some industry experts say the growing farming row could lead major soya importers, like China, to turn to Brazil and the US for suppliesThis article is from the BBC News website. © British Broadcasting Corporation