Environment Secretary Michael Gove has warned the Oxford Farming Conference that there would be considerable turbulence to sectors such as agriculture if the UK left the EU without a deal.
While he said a nation like the UK would flourish over time even without a deal, he said "the turbulence which will be generated by our departure without a deal would be considerable.
"It would hit worst those who are our smaller farmers and farm businesses."
He said tariffs, border checks, potential delays for recognition of organic products and labour pressures would all add to costs for food producers.
"Nobody can be blithe or blase about the real impacts on food producers in this country of leaving without the deal," he told the conference.
'More vibrant farming sector'
He did, however, say that leaving the EU would free the farming sector from the "bureaucratic straightjacket" of Europe's Common Agricultural Policy.
"[The UK will] develop a more vibrant farming sector with access to technologies on which the EU is turning its back", he added.
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"Leaving the EU will end support for inefficient area-based payments, which reward the wealthy and hold back innovation, and we can move to support genuine productivity enhancement and public goods like clean air, climate change mitigation or the improvement of soil, or water quality or improvements to pollinator habitats."
It would give the opportunity to support organic farming, landscape restoration and improving public access, he said
"All of these are real gains that our departure from the EU can bring, but these real gains risk being undermined if we leave the EU without a deal," he warned, urging Parliament to support the Prime Minister's deal.