The UK’s food security is to be regularly assessed by parliament to ensure minimal disruption to supplies after the country leaves the EU and while new trade deals are sought.

The commitment will be part of the biggest shakeup of British agriculture in 40 years and requires a regular report to MPs outlining supply sources and household expenditure on food, as well as consumer confidence in food safety.

The move reflects concerns over potential disruptions post-Brexit, as more than a quarter of Britain’s food comes from the EU and nearly a fifth from other countries.

The revision is one of a handful to the agriculture bill, introduced to parliament on Thursday more than a year after the previous government was forced to abandon the legislation amid Brexit turmoil.

Other changes include a stronger emphasis on the soil, at risk from overuse, erosion and nutrient loss; farmers are to receive help maintaining healthy soils, as well as with improvements to the tracing of livestock movements between farms. There will be powers to regulate fertiliser use and organic farming after Brexit.

Missing from the bill is a binding commitment to prevent trade deals allowing the import of food produced to lower standards than those to which British farmers must adhere. This has been a key demand of farmers concerned that after Brexit they will be undercut by cheap imports from the US and Asia, with lower food safety and animal welfare regulations.

Theresa Villiers, secretary of state for the environment, food and rural affairs, called the revised bill “one of the most important environmental reforms for many years” and said it would protect nature and biodiversity and help meet goals on the climate crisis.

“[This] will transform British farming, enabling a balance between food production and the environment which will safeguard our countryside and farming communities for the future,” she said. “We will move away from the EU’s bureaucratic common agricultural policy and towards a fairer system which rewards our hard-working farmers for delivering public goods, celebrating their world-leading environmental work and innovative, modern, approach to food production.”

At the heart of the bill is a shift away from the EU system, where farmers receive subsidies based on the amount of land they farm, to a process whereby farmers are paid for the public goods provided, including clean water, clean air, healthy soils and habitats for wildlife.

There will be a seven-year transition period for farmers to move from the current regulations under CAP, the EU’s common agricultural policy, to a system of environmental land management contracts. Under these contracts, individual farmers will agree with the government a tailor-made set of goals with details on the measures they will take to manage their land and protect the environment.

For the duration of the current parliament, subsidies at the same rate as the EU – about £3bn a year – will be paid to farmers from taxpayer funds, but some of the richest farmers who benefit most from the system can expect to lose out when the new contracts are phased in.

Farming leaders were disappointed at the lack of a legal commitment to ensure trade deals did not allow entry to cheap, low quality, imports.

Minette Batters, president of the National Farmers’ Union, said: “Farmers across the country still want to see legislation underpinning the government’s assurances that they will not allow the imports of food produced to standards that would be illegal here through future trade deals. We will continue to press the government to introduce a standards commission as a matter of priority to oversee and advise on future food trade policy and negotiations.”

Organic farmers were also concerned, saying the bill did not go far enough in supporting farmers to tackle climate and ecological emergencies.

Gareth Morgan, of the Soil Association, said: “Much more is necessary to bring the radical changes our farming sector needs. Small tweaks to the status quo will not suffice. It is disappointing that the bill still does not commit to support farmers to adopt nature friendly agro-ecological farming, like organic, or environmental action across the whole farm, rather than in small areas. Nor does it signal support to enable the radical shift away from artificial fertiliser and pesticides needed to restore nature and soils capable of storing carbon.”

How soil offers hope for the climate crisis

The specific attention paid to soils was welcome, but more detail would be needed on how to implement measures to protect soil health, said Matthew Orman, director of the Sustainable Soils Alliance. “The commitment for all soils to be sustainably managed by 2030 is now 10 years old. For this to be achieved, an ambitious strategy linking all the policy mechanisms – education, regulation, assessment and incentivisation – with clear milestones for delivery, is urgently needed.”

Vicki Hird, farm campaign coordinator at Sustain, an NGO coalition, highlighted new provisions in the bill to improve oversight of the supply chain. Under these changes all sellers of agricultural produce will qualify for protection from abuse by business purchasers, which she said would help drive out unfair practices and protect farmers and could also aid reduction of food waste.