Heir to the throne Charles has farmed at the 1000-acre plot near his country home Highgrove in Gloucestershire for 35 years.

It is understood the prince, 71, could not commit to a new 20-year-lease, due for renewal in the spring of 2021, as he is expected to become king at some stage.

The move is a practical one, with Charles unlikely to be able focus on the farm when devoted to his duties as a monarch.

Produce from the farm was used by the prince to start the Duchy Originals brand, now known as Waitrose Duchy Organic, with its wheat and oats used to make the first product, the now famous Duchy Originals oaten biscuit.

A Clarence House spokesman said: "The Prince of Wales will not be renewing his lease on Home Farm but will continue to farm organically at Sandringham."

The prince will keep his beloved Highgrove as his country retreat, and will not have a new home at Sandringham in Norfolk.

Focusing his farming activities on Sandringham, the prince already manages the Sandringham estate on behalf of the Queen, taking over the role from the Duke of Edinburgh.

Sandringham's own Home Farm has been converted to organic farming.

The Sun newspaper reported that quitting Home Farm near Tetbury in Gloucestershire would be a "wrench" for the prince, who has devoted decades to its development.

A passionate advocate of the benefits of organic farming, Charles began converting the Duchy of Cornwall farm to a completely organic system in 1985.

The prince is the Duke of Cornwall and entitled to the annual surplus of STG22 million ($A40 million) generated by the Duchy of Cornwall's vast portfolio of land, buildings and financial investments.

Highgrove and Home Farm are owned by the Duchy and leased by the prince.

A new unnamed non-royal tenant has been found for the farm, which will remain organic, and they will continue the relationship with Waitrose Duchy Organic.

Australian Associated Press