One in four farm workers could be out of a job in the next 10 years as farms become more streamlined, according to a leading economist.

Sean Rickard, of the Cranfield School of Management, says the farming industry as a whole is probably overmanned and will be forced to shed jobs - like the coal mining, steel working and car manufacturing industries.

In an interview with BBC One's Countryfile programme, Mr Rickard predicted that more than 100,000 people would be forced out of the agricultural industry "sooner rather than later" as it became more streamlined.

In what will be seen as a further blow to the beleaguered agriculture industry, he said the bulk of farm foods would be produced by just 20,000 farmers - just 20% of the current number.

"Given that the industry's been subsidised for over 30 years, it would be amazing if it was not over-manned and if there were not great inefficiencies," he told the programme.

A report by the National Farmers' Union last October found that 90% of farmers were suffering stress due to long hours, poor financial returns and fears of future instability.

'Changing nature of farming'

Mr Rickard added: "It's very tough, it's very painful and there are lots of social tragedies at the time it's done.

But he said "two or three years down the road" other industries had put themselves in a much stronger position by streamlining and "growing again".

"That's what agriculture needs to do," he added.

But Barry Leathwood of the Transport and General Workers' Union said the continued growth of new sectors such as organic farming could stem the flow of farm workers from the countryside.

"Many people are becoming self-employed contractors travelling around the country doing jobs that would otherwise be done by full-time workers based on individual farms there.

"Whilst the nature of farming is changing it doesn't mean all those people are disappearing from rural areas."