The NFU has said farmers should continue to follow Common Agricultural Policy (CAP) rules for at least two years after Brexit to ensure stability and give Government time to adjust to any changes.
The union has made the recommendation as part of a proposed three-phase transition from the CAP.
Phase one would allow minor improvements to CAP rules, but most measures would be kept in place. It would also provide an opportunity for new ideas to be piloted.
NFU president Meurig Raymond said: "Past experience has shown CAP reform decisions have often been implemented in a rush or in the absence of policy certainty, creating delivery problems and delays to payments.
"Whilst it might appear attractive to make fundamental changes on day one of Brexit, the NFU feels there is a balance to be struck between ensuring regulatory stability and effective delivery of a new policy and the ambition for tangible change in our agricultural support regime in the short to medium-term."
The second phase of the union’s proposed transition would see CAP legacy schemes continue, but allow for greater review and assessment of the pilots introduced in earlier years.
With more information about new trading conditions available in phase two, the NFU has also called on the Government carry out an analysis of the impact of the Brexit settlement on farming during this stage.
The final phase would see the switch to a new domestic agricultural policy.
Mr Raymond said: "A well-thought out transition is vital to ensuring as much certainty and stability as possible.
"Different political decisions and their implementation will have differing impacts on farming’s readiness to move away from the current CAP.
"With a Brexit settlement which promotes a positive future for British farming, the first two phases could be completed in four years, with a new system implemented as early as 2023.
"But a disruptive Brexit which damages the prospects of British farming would mean maintaining the stability of the current system for a much longer period.
"What is clear is farming’s appetite to move to a new way of doing things which promotes greater productivity on farm, protects and enhances the environment and guards against volatility in the sector."