Argentine farmers will increase protests ahead of presidential elections in October 2015 to push candidates toward reforming policies that growers say are killing their profits, said Omar Principe, the new head of one of the country's main farm groups.

Demonstrations in the past have stopped Argentine farm exports for months, straining government revenue and putting upward pressure on world food prices.

Two of the three presumed main candidates have promised to lower the 35 percent export tax that the government slaps on soybeans and loosen the strict corn and wheat export quota system that growers say complicate crop planning.

Principe, named head of the Argentina Agrarian Federation earlier this month, said growers will increase the pressure on candidates as October nears.

"The candidates are going to present their platforms and we are going to have to have an impact if we want to change the policy model," he told Reuters in an interview.

"Next year will be one of massive mobilization. We are going to put the issues that are facing small and medium-sized farmers in front of the candidates," he added.

Argentina is the world's No. 3 soybean exporter and top supplier of soymeal livestock feed. It is also a major producer of wheat, shipped mostly to neighboring Brazil, and corn.

The government of President Cristina Fernandez was shaken by massive farm protests six years ago over her tax policies. The 2008 farm rebellion reduced exports for months and cut into government revue. Relations between the two-term leader and the key grains sector have been severely strained ever since.

Banned from running for a third consecutive term and with a year left in office, Fernandez has shown no sign of loosening the policies that farmers say weigh on production and investment.

Buenos Aires Governor and presidential hopeful Daniel Scioli, from Fernandez's branch of the Peronist party, has not yet staked out a position on farm policy.

But leading opposition figures Mauricio Macri, mayor of Buenos Aires, and Congressman Sergio Massa say it is time to start cutting export taxes and loosening export quotas.

Meanwhile, tensions between the government and the farm sector are increasing.

Argentina's state bank has moved to bolster the country's foreign exchange reserves by cutting credit to soy farmers who are holding onto an estimated 8 million tonnes of last year's beans as a hedge against one of the world's highest inflation rates.

The bank hopes to force farmers to sell soybeans in order to finance their operations, thereby boosting the supply of beans available for export and enabling the government to collect more export tax revenue.