An alarming decline in food production at British farms will leave shoppers at the mercy of prices and quality elsewhere in the world, warns a UK farming report.
The National Farmers Union has forecast a sharp rise in the amount of imported food as British farms convert into renewable energy sites and tourist attractions to stay afloat.
Minette Batters, deputy president of the NFU, said Britain was rapidly becoming less self-sufficient because support for domestic farming was considered less important by politicians who preferred to promote the "globalised economy".
Batters said the amount of home-grown food would reach new lows unless farmers received stronger backing from Westminster.
Britain was becoming increasingly vulnerable to global tensions, she said, and would develop a reliance on the co-operation of other nations in the same way that it depends on Russia and the Middle East for oil and gas.
Research showing a disturbing decline in food production was presented at the NFU annual conference last week.
The NFU urged MPs to treat food security with the same importance as education and health in their manifestos for the forthcoming election.
"Food production in Britain is shrinking and it's already getting close to covering just 50 per cent of our needs," Batters said.
"We take food for granted because the shelves are never empty in the supermarkets and children are not being taught where their meals come from.
"But we live in uncertain times and events such as the Icelandic ash cloud and the fires and droughts in Russia a few years ago bring home the importance of self-sufficiency. Action is needed now to reverse this negative trend."
Falling prices of grain, milk and price wars between supermarkets have hit farmers' profits and forced many to diversify, she said.
In some instances, this has meant installing wind turbines and feeding electricity back to the grid. Others have turned their land into attractions by hosting weddings or offering family days out.
The NFU recommended that the next government gives farmers incentives to grow vegetables, grains and rear animals to secure the food supply for the next generation.
"If we are subjected to larger quantities of imported food in the future, there is no guarantee that it will be of the same high standards as the produce from British farms," Batters said.