The research by consultancies Oxford Economics and The Andersons Centre for the Crop Protection Association also found that a ban, currently being debated by the European Commission, would reduce tax revenues from agriculture and its supply chain by £193m, as well as potentially pushing up food prices.
Oxford Economics director of consulting Ian Mulheirn said: "Our report’s findings are very clear, a glyphosate ban will negatively impact UK GDP and agriculture, at a time of real uncertainty for British farmers.
"If glyphosate was not approved for use in the UK but remained available in the rest of the world, this would place domestic production at a considerable disadvantage."
Lincolnshire arable farmer Andrew Ward added: "A ban would also be really bad for the environment. We’d have to use bigger vehicles and do more ploughing which would mean greater carbon emissions and less biodiversity."
At this week's Cereals trade show, NFU president Meurig Raymond said the union would continue to make the case for agro-chemicals regulation based on "robust scientific evidence".
"We find ourselves once more at a point in time with glyphosate teetering on the edge of being lost, and a threat of further bans on neonics with no evidence that this is helping bees, as well as a political fudge on defining endocrine disruptors," he said.
"The NFU is working hard to influence the debate and we are urging the new government to support us in this fight."