The application will see extraction take place at Auchencorth Moss, near Penicuik, over the next two decades, just metres away from Auchencorth Moss site of special scientific interest.
Dr Maggie Keegan, Head of Policy, Scottish Wildlife Trust said: “It’s incredibly disappointing that the destruction of peat bogs continues to be permitted while millions of pounds are being spent on their restoration elsewhere as part of Scotland’s commitment to reducing carbon emissions.
“While we accept the moss has suffered damage in the past we believe it is possible to restore it to become an active bog that is rich in wildlife and acts as a carbon sink, helping Scotland meet its obligations to fight climate change.
“Lowland raised bogs are among the rarest and most threatened habitats in Europe, and take thousands of years to form.
“Auchencorth Moss accounts for one-fifth of Scotland’s total carbon emissions from peat extraction so refusing this application would have gone a long way to reducing the environmental impact coming from this sector.
“Approving this application also goes against national and local policies that are aimed at phasing out the extraction of peat for use in horticulture. Peat free composts have been available for many years so there is absolutely no need for this archaic practice to continue.”
A Midlothian Council spokesman said: “Peat extraction at Auchencorth Moss in Midlothian was granted planning permission in 1986. This planning permission expires in February 2042.
“The recent application was to review the conditions attached to the original planning consent. However, this review process places restrictions on the local planning authority and, as a consequence, it cannot restrict working rights such as to prejudice adversely to an unacceptable degree either the economic viability of the operation of the site or the asset value of the site.
“Any conditions which restrict the size or depth or height of the extraction area, the rate of extraction or deposition, the length of time before expiry of the permission, a reduction in the total quantity of minerals permitted to be extracted or mineral waste to be deposited would create a compensation liability.
“Midlothian Council has managed to secure the restoration of the site to a raised bog rather than to agricultural land as stated in the original planning permission.
“Furthermore, the applicant is also required to provide financial provision to secure the decommissioning, restoration and aftercare of the site.
“We are working with the Scottish Environment Protection Agency and Scottish Natural Heritage.
“The Local Planning Authority has worked with the Scottish Environment Protection Agency and Scottish Natural Heritage to ensure the best possible outcome considering the restriction of existing legislation.”