Argentina, one of the world's top food exporters, announced emergency measures Monday to help farmers and ranchers affected by the most devastating drought in decades.

Speaking from the presidential residence of Los Olivos, President Cristina Kirchner said that the measure targets "those regions and provinces that are affected by this phenomenon."

The decree exempts farmers and ranchers in the country's agricultural heartland from paying taxes for one year. It also excuses them from paying cargo permit fees, valued at 57 million dollars a year.

Nearly 1.8 million heads of cattle have died of hunger due to grasslands drying up, and more than half of the country's wheat and corn crops have been lost due to the lack of rain.

The drought has already cost Argentina four billion dollars and has burdened the state with some 1.88 billion dollars in lost tax revenue, according to some private estimates.

Argentina -- a top supplier of wheat, corn, beef and soybeans -- exports around 35 billion dollars of food produce a year. Farm exports amount to more than 50 percent of foreign sales in the South American country.

Top markets for Argentine produce include other South American nations, the European Union and Asian nations.

"We call on everyone to display great patriotism and effort" in the aftermath of the government's drop in tax income, Kirchner said.

The drought is also hurting farmers in Brazil and Uruguay.

In 2008, farm land in the provinces of Santa Fe and Entre Rios received only 40 percent of their annual rainfall, low levels not seen since 1961, according to data from the Argentine Meteorological Service.