Fifty full-time farmers have left the land each week since 1997, Fine Gael leader Enda Kenny told the Dáil.
The average farming income then was €14,000, he said. "Since then, in many cases, farmers' incomes have reduced and average farming income now stands at just €15,000, while the average industrial wage is at €30,000 per annum," Mr Kenny added.
He said that in 1997 the State had 130,000 full-time farmers, but this number had declined by 17,000 to the current level of 113,000.
Mr Kenny noted that thousands of farmers had taken to the streets earlier in the day in protest at the European Commission's proposals for the next round of the World Trade Organisation talks scheduled for Hong Kong next month.
"The Taoiseach should be aware that the farming community is very fearful of the proposals made by the European Commissioner, Mr Mandelson, who has proposed cuts in tariffs of up to 60 per cent in some areas," he added.
"These proposals would spell the end for small and medium-sized farmers in Ireland and throughout the EU, and could cost the Irish food sector €800 million."
Mr Kenny said the farming community was given clear assurances during the lead-up to the Cap reform in 2003 that the reform would form the negotiating position for the talks.
"Irish farmers signed up for Cap reform with the then commissioner Mr Fischler on that basis," he added. "They are now being told they will need to accept more cuts. The ink had hardly dried on the Fischler proposals, and the cheques had barely started to come through, and they are now being told there is no certainty that these will deliver for farmers."
Taoiseach Bertie Ahern said negotiations on the matter had been going on for some considerable time.
There had been a series of rounds of discussions both within the European Union and with the Americans.
"Throughout these negotiations we have taken the line that we are in favour of a successful round in the World Trade Organisation talks," he added.
"We want to see the Doha round concluded. For the sake of trade and trade liberalisation, and to allow for world trade, particularly for developing countries, we want this round to be successful."
Mr Ahern said the Government had been adamant in its position that the 2003 negotiations, which led to the latest round of Cap, building on the 1992 round, and the three other negotiations of Cap in recent years, should not be given away.
There had been some disagreement in the negotiations with Commissioner Mandelson.
"Our view on the negotiations is that we have already given a significant round of concessions in the 2003 agreement," said Mr Ahern.
"Therefore, our opening position should be that there is no need for us to give further breaks and changes, pending what the Americans will or will not give."
