Tossed up onto Scottish beaches by the tonne, seaweed is finding a place at the table thanks to the fashion for foraged food.

But it could also play a vital role in returning acres of abandoned farmland in Scotland to production, according to new research.

Ecologists from Scotland's Rural College and Edinburgh University have been studying some of the UK's remotest farming communities, the talamh dubh or "black land" crofts on the east coast of North Uist.

Parallel ridges on hill sides on North Uist are remnants of old agricultural systems that the ecologists believe could be used to increase productivity on land that is now largely unused. And seaweed could prove a key ingredient in the process.

HeraldScotland: Seaweed Festival

Crofting counties of the North West Highlands and Islands of Scotland make up 16 per cent of land in the UK.

Today, 375,000 people and five million sheep live there, yet the area imports 95 per cent of its food.

Between the 14th and 18th centuries, however, the area was home to over half a million people and was 90 per cent self-sufficient in food.

To find out how best to return some of this land to production, the researchers combined modern science with traditional detective work, collecting community memories and Gaelic words, and poring over historical documents and old photographs.

According to lead author Dr Barbra Harvie of SRUC: “Most of this agricultural land has lain abandoned for more than 60 years and local knowledge of how to manage it is rapidly disappearing. By interviewing crofters, we are gleaning vital knowledge before it is lost forever.”

The studies also involve some hard graft. She said: “After researching historical crop rotations we have replicated these in the field by hand-digging ridges and hauling seaweed from the coast.”

Their results show that local and historical knowledge is vital for reinstating this kind of farming, that modern agricultural machinery cannot be used, and that seaweed is a useful and sustainable addition to the system. "We are looking at the science behind it," Dr Harvie said, "to try to explain why it's worth using again."

The agricultural system that used to be in operation in North Uist has fallen out of use with the land given over to sheep.

Re-using this abandoned land for agriculture could have major benefits in both agricultural and ecological terms, Ms Harvie believes.

She added: "The ecological impacts of recultivating abandoned croftland are minimal compared with the carbon footprint associated with importing food from the mainland.

“Returning even some of these abandoned croftlands to agriculture could help alleviate some of the issues of food security and a return to higher levels of self-sufficiency in these remote, less-favoured farming regions of the highlands and islands."

Seaweed has been gaining a reputation as something of a "superfood" in recent years, although it has been gathered for food in Scotland, Ireland and Wales for centuries and has been a food source in Asia from at least 600BC. It is renowned for its high protein content. But the ecologists also believe this natural resource so abundant on the British coast can also be hugely useful in crop cultivation.

The ecologists from SRUC and Edinburgh University are now hoping to further their research by investigating what makes seaweed so good for the soil. Furthermore, they also hope to engineer more appropriate farming tools for the croftlands as modern agricultural machinery is unsuitable, designed as it often is for flat fields.

Ms Harvie will present the team's findings to the British Ecological Society annual meeting in Edinburgh today.