Farmers are calling for the Government to intercede and block the sale of Australian grain company GrainCorp to Archer Daniels Midland (ADM), a major group in global agribusiness.

Opposition from farmers to the $3 billion takeover is growing, after more than 280 farmers at a conference in Sydney called on Federal Treasurer Chris Bowen to block the sale, using his powers under the Foreign Acquisitions and Takeovers Act.

The snowballing anti-ADM sentiment follows mounting concerns that the sale will destroy competition in the grain market, coupled with fears the takeover of GrainCorp will mean the closure of country silos and increased freight, storage and handling costs for growers, while ADM searches for "efficiencies".

The chairman of the Senate Committee on Regional and Rural Affairs, Bill Heffernan, has repeatedly raised concerns about court cases involving ADM, including proven charges of price fixing, bribery and corruption in grain markets.

"NSW farmers do not agree to the sale of GrainCorp as they most certainly do not believe it's in the best interest of the grains industry or Australia," Opposition agriculture spokesman John Cobb said, "they have sent a clear, unequivocal message (about this) deal which will result in virtually all grain export facilities in Australia, except for WA, being foreign-owned."