Farmers will need to earn their subsidy payments after Brexit by delivering benefits for nature rather than relying on EU handouts for the amount of land they farm.

That was one of the messages from Michael Gove's first major speech as environment secretary, during which he said Brexit was 'an historic opportunity' to review policies on agriculture, land use, biodiversity, chemical regulation and animal welfare.

Mr Gove reiterated an earlier pledge that the government would continue to match the annual £3bn of subsidies currently given to UK farmers by the EU's Common Agricultural Policy (CAP), until at least the end of 2022.

But rather than the current EU system of direct support based on acreage, he indicated that future farm subsidies will be assessed on the environmental and public benefits delivered by farmer, such as woodland creation, habitat protection, and better animal welfare.

'The CAP rewards size of land-holding ahead of good environmental practice, and all too often puts resources in the hands of the already wealthy rather than into the common good of our shared natural environment,' he said. 'It also encourages patterns of land use which are wasteful of natural resources and often intrinsically poor value rather than encouraging imaginative and environmentally enriching alternatives.

'We need to take the opportunity that being outside the CAP will give us to use public money to reward environmentally-responsible land use.'

Farmers' leaders in East Anglia agreed that the UK's new farm policy must work for both food production and the environment – but said much would also depend on the degree to which post-Brexit trade deals protected British producers, as this would dictate how much financial support would be needed.

Robert Sheasby, regional director for the National Farmers' Union in East Anglia, said: 'Over the years, farmers have been delivering environmental measures but we need the right mechanism in place to continue that.

'Whatever comes in the future, we need it to cover productivity, the environment and profitability. When speaking to our members, one thing that comes across loud and clear is that if we have got profitable farming, we can deliver the environment the public wants. That is partly about having a safe and stable supply of food.

'The last CAP reform delivered greening measures and environmental conditions, so we have already been delivering public goods within the existing scheme, so initially this is not a radical idea.'

Mr Gove's speech comes after he told the Commons that UK policy on neonicotinoid pesticides, which have been linked with bee declines, will follow existing EU protections and will be 'enhanced in line with the science'.

Rebecca Newsom, policy adviser at Greenpeace UK, said Mr Gove had made a 'number of promising statements' about reforming farm subsidies, enhancing nature and looking after bees.

'The question is whether and how these words will turn into actual government policy,' she said.

'For decades, it's EU environmental law that has cleaned up our beaches, banned dangerous chemicals and held Gove's own department to account for its failure to tackle illegal air pollution.

'Without the bedrock of these regulations and an authority to enforce them, a dirty Brexit will be far more likely than a green one.'