The Irish Farmers Association has said the deal reached between the EU and the UK is a relief, but that it will pose significant difficulties for the Irish agri-food sector.
IFA President Tim Cullinan said while the work of the two sides to avoid a 'no-deal' has to be acknowledged, he said the eventual outcome leaves little reason to celebrate.
Mr Cullinan commended the work of the EU chief negotiator Michel Barnier for his patience and perseverance in pursuit of an outcome that steered away from a crash-out situation.
"We have real concerns about how non-tariff barriers will impact on our ability to keep trade flows moving.
"The scenes at Dover this week, with hundreds of trucks backed up and freight delayed, does not bode well.
"Green Lanes have been implemented previously for food exports. These must be prioritised after January 1," he said.
Mr Cullinan said the Government and the EU must have the €400m support fund for Irish farmers ready in the new year to address any market disturbance and he said the €5 billion EU Brexit adjustment fund must also be available.
According to Mr Cullinan, the longer-term implication for food exports could be the flooding of the UK market by cheap imports.
"Farmers here on the island of Ireland and in the UK are steadfast in their view of standards.
"The danger is that the deal isn't robust enough to ensure the regulations of the Single Market are adhered to," he said.
The IFA said it will be analysing the detail of the deal to evaluate the impact on Irish food exports.
"We have consistently said that Irish farmers are at the top of the queue, and that the Irish Government will have to bring forward support for our farming sector," he said.
'Potential disaster averted'
Meanwhile, the President of ICMSA Pat McCormack has said that the deal has averted a "potential disaster" for Ireland's agri-food sector and the wider rural economy that depends on that sector.
Mr McCormack said that with over 50% of Irish beef and 30% of dairy exports going to British markets we have sold into for centuries, the imposition of tariffs and quotas would have been "hugely damaging".
He said we can now look forward to 2021 with "greater optimism" in the knowledge that a huge threat has been removed.
Mr McCormack said he was cognisant that the devil could be in the detail and ICMSA will be analysing the relevant articles in the coming days to establish the exact impact on our sector.
'Brexit deal has been long awaited'
The Ulster Farmers' Union (UFU) said the Brexit trade deal that was reached this afternoon has been long awaited and marks a significant milestone.
UFU president Victor Chestnutt said it is good news for Northern Ireland's agriculture industry and is the start of a new beginning.
However, he said many challenges lie ahead for farming following this historic Brexit breakthrough, from establishing new trade deals to designing a domestic agricultural policy.
"Since the Brexit referendum result the UFU has been lobbying to achieve the best possible outcome for NI farmers. Our aim has always been focused on ensuring free and frictionless trade could continue north/south and east/west.
"The trade deal means that like NI, there will be no tariffs or quotas applied on trade between the EU and Great Britain.
"We do need to analyse and fully consider the potential for regulatory divergence between GB and the EU, as the controls and procedures which NI now faces are changing unrecognisably.
"A lot of lobbying with both the UK Government and the EU will be needed to try and mitigate against the worst impacts of these changes to ensure that we have time to adjust and can keep trade flowing," he said.