The NFU and a coalition of environmental groups have warned that a 'no deal' Brexit could bring farms to the "brink of collapse".
The NFU and Greener UK, a group of 13 environmental organisations, say it is hard to envisage a "worse deal than no deal."
The two groups are working together to demonstrate how a Brexit deal can work for both farming and the environment.
Greener UK is a group of 13 major environmental organisations, with a combined public membership of 7.9 million. It is tracking Brexit to make sure that environmental protections are not weakened or lost.
Producing food from the land and caring for the environment have all too often been framed as being in conflict.
There are still uncertainties as to how farmers will manage the land both for food production and for the public goods the market won’t pay for.
But both organisations agree that the natural environment cannot be managed in the absence of a profitable and productive farming sector.
'Cliff edge Brexit'
In a joint statement, the NFU President Minette Batters and Greener UK chair Shaun Spiers agreed that there must be "free and frictionless" trade between the UK and EU.
Both leaders explained that a "cliff-edge" Brexit could bring farms to the brink of collapse and undermine the protection of the environment.
Upholding properly enforced regulation, high standards of animal welfare and environmental protection must not be undermined by any future trade policy, they said.
"Free trade deals with countries with lower standards could have a potentially disastrous impact both on the farm businesses we will need to care for our countryside, and on public health. High environmental and animal welfare standards should not be a negotiating chip in trade agreements," the statement said.
"Furthermore, as we would increasingly rely on the rest of the world to feed us, we run the risk of exporting the environmental impact of farming. It is hard to see how this is the Brexit bonus anyone voted for."
The two organisations say "much unites" farmers and environmentalists, such as the importance of a Brexit deal that enables farmers to continue to produce high quality food and go further with environmental improvements.
"And when it comes to our future relationship with the EU, as far as farming and the environment are concerned, it is difficult to envisage a worse deal than no deal," the NFU and Greener UK added.
'Heard, received and understood'
The joint-statement follows Defra Secretary Michael Gove announcing that he has "heard, received and understood" a call by farmers to uphold high-quality British food production in post-Brexit trade agreements.
Mr Gove said British farmers must be better equipped than anyone to fulfil the national and global demand for high quality food.
The comments come as part of a speech from Mr Gove at the NFU Summer Reception, which took place earlier this week.
It welcomed over 60 parliamentarians to the House of Commons Terrace to speak to farmers and show their support for the British farming sector.