Crops of oversize organic vegetables grown by a Scottish couple are being studied by scientists.
Oversized cabbages are a common sight
Cameron and Moira Thomson have produced onions the size of footballs and strawberries the size of apples on what was a boggy hillside near Blairgowrie.
Mr Thomson said the secret of their success had been remineralising their ground with simple rock dust.
Scientists from Glasgow University have begun a three-year study of the Thomsons' pioneering work.
Viewers of BBC Scotland's Beechgrove Garden programme will see the results of the Thomsons' work on Thursday night.
The former art teachers have spent 20 years experimenting with remineralisation.
In 1997 they set up a charitable trust, the Sustainable Ecological Earth Regeneration (Seer) Centre and planted 64 trial plots of land to carry out research into organic gardening.
The plots were spread with crushed-up volcanic rock and the crops harvested in July. Experts have now started a three-year examination of their work.
Mr Thomson, 56, said that their land at Enochdhu had been transformed from "infertile, poorly-drained upland grazing".
At first, people thought they were "cranks" but the couple have spent years "ploughing on".
Microbes and worms
Last year, the Thomsons planted a trial patch of potatoes between June and July, normally too late in the season, but despite predictions there was a bumper crop.
He said: "We got massive spuds out of there, bigger than mangos.
"They had less water in them and last so much longer than anything you would ever have seen before. We were eating them until about a fortnight ago."
He added: "People see giant vegetables and think 'how can they be organic?'"
The land has been transformed by rock dust
The project has received more than £150,000 in Scottish Executive funding to help trial the application of rock dust in agricultural systems and to maintain its staff and gardens.
Rock dust was spread over the crop trials and left for microbes and worms to naturally fertilise the land and replenish it with up to 75 minerals and trace mineral elements.
The Thomsons source the dust for free from the Collace quarry, with Tayside Contracts, who service roads in Perth and Kinross, Tayside and Angus, agreeing to provide them with as much as they require.
Mrs Thomson, 42, said: "Rock dust is the perfect way at getting the earth back to full health."