The government has "thrown too much money down the chute" on land reform, Minister in the Presidency Trevor Manuel said.

Opening Agri SA's annual conference in Stellenbosch yesterday, Manuel noted that the price of agricultural land was high and that areas often lay fallow for a decade - with no investment made in them - before a sale went through.

"By the time there is an actual payment, there is no correspondence with the price of the land," Manuel said.

"We need to look at this issue very differently."

President Jacob Zuma, in his State of the Nation address earlier this month, alluded to the government's plan to review the willing-buyer-willing-seller principle that had been underpinning land reform since 1994.

Manuel told the conference that the issue of land reform was "sensitive".

He did not elaborate, saying only that land reform was necessary and a "constitutional imperative".

Among the politicians attending the conference, which ends today, is Agriculture, Forestry and Fisheries Deputy Minister Pieter Mulder, who last week controversially raised the historical basis for land reform in the national assembly.

Manuel, who chairs the National Planning Commission, said South Africa's population was about 50 million and could rise to 58.5 million by 2030.

This meant that farmers would have to increase agriculture outputs by 20% to meet a growing demand for food.