By Hans-Edzard Busemann

BERLIN, March 26 (Reuters) - A planned free trade agreement between the European Union and United States should not completely liberalise agricultural trade, the president of the association of German farmers' association DBV said on Tuesday.

Trade talks must involve upper limits to exports to prevent market disruption, Joachim Rukwied told Reuters.

Brussels and Washington hope to start negotiations in June on a transatlantic free-trade agreement which would encompass almost half the world's economy, and are seeking as broad a deal as possible to deliver strong economic growth.

The negotiating mandate proposed by the European Commission, which has kept its contents secret, must be approved by EU governments before the talks can start and agricultural trade is seen as a contentious issue.

Rukwied said he did not expect free trade to open the way for hormone-treated U.S. meat or genetically-modified (GM) foods into Europe.

Germany has an agricultural trade deficit with the United States, the association calculates. Germany exported 1.5 billion euros ($1.93 billion) of agricultural products to the U.S. in 2011 but in the same year imported 1.7 billion worth from the United States, the association said.

Rukwied said he sees export opportunities for German food such as dairy products and sausages to the United States.

The EU currently imports large volumes of feed grains from South America; whether these could be replaced by U.S.-origin cereals after the free trade agreement would depend on market price, he said.