The Countess Sondes hopes to raise the profile of non-food crops

The trial at Leeds Castle is being used to highlight the importance of such plants in modern agriculture, said castle trustee Countess Sondes.

Eight non-food crops - including hemp, linseed and calendula - will be grown.

The countess said they would enhance biodiversity and could be harvested for use by the textile, pharmaceutical and automotive industries.

Countess Sondes has met representatives of the United Nations to discuss the importance of non-food crops.

It has praised her decision to turn over part of the 500 acres of parkland at the castle to raise the profile of sustainable crops.

Farmed hemp is used by the cosmetics and textiles industries

Amir Dossal of the UN Fund for International Partnerships said: "I would like to commend Leeds Castle in their forward thinking in showcasing non-food crops to the public as a way of supporting a sustainable future."

The countess already grows non-food crops at the Lees Court Estate, near Faversham, which she owns.

She said growing plants like echiam, which is used to make creams and lotions by the cosmetic industry, had proven profitable.

She also believes non-food crops represent the way forward not just for farmers, but also the environment, and hopes visitors to the castle will gain some insight into sustainable farming methods.

Crops to be grown on a 200m strip near the castle's yew maze include hemp, which is used in cosmetics, textiles and bedding; calendula, which is used in food dyes and by the paint industry; and linseed, whose fibre is used for paints and varnishes, and which is also used in health food products.