Queues of traffic have formed round the Eikon Centre in Lisburn, where farmers are gathering at a rally to protest against changes to inheritance tax.
The event, organised by the Ulster Farmers' Union, is also being attended by politicians as well as agricultural leaders.
Farmers say the cap of £1m on agricultural property relief announced in the budget last month will see the next generation deterred from taking over family enterprises.
The rally has been called ahead of national protests in London on Tuesday.