At least £4.4 billion a year must be invested in nature-friendly farming by the government over the next decade to meet legally binding targets, charities have said.
The funding needs to be directed solely towards agri-environment schemes that will allow the UK to achieve its net zero and nature targets, according to the report.
The UK government currently spends about £3.5bn in total on agricultural subsidies each year.
Written by an independent economist for charities RSPB, National Trust and the Wildlife Trusts, the report warns that the ‘scale of need’ has risen due to 'ongoing declines'.
It blames the government for not tackling the issue, leading to new environmental commitments and legally binding targets, most notably to achieve net zero greenhouse gas emissions.
In addition, factors such as the war in Ukraine and the associated cost of living crisis have led to significant changes in the cost drivers impacting UK agriculture.
The findings, launched at the regenerative farming festival Groundswell, come as pressure grows on the governments of the UK to explain how farmers will be supported for their delivery of nature-friendly practices.
Katie-jo Luxton, director of conservation at the RSPB, said the charities were concerned that current schemes were "simply not on track" to support farmers to deliver change.
"Put simply, nature underpins our ability to produce food, and without a system resilient to the challenges of the nature and climate emergency, we put our own long term food security at risk.
“Farmers need certainty that the necessary policies and support are in place if they’re to produce healthy food while helping to reverse wildlife declines and restore the environment."
Harry Bowell, director of land at the National Trust, added that the government must 'properly invest' in nature-friendly farming.
"As this report shows, the scale of need is growing, and decisive action is urgently needed to support farmers to bring back nature and tackle climate change while producing food sustainably.
“Instead of the uncertainty many are facing, farmers – and the wider public – need assurance that government promises will translate into proper investment.
"This is a critical moment in the future of our countryside and politicians must step up.”