A live bomb waiting to explode at any minute was found in grounds containing the country's biggest composting site last week.
The high explosive artillery shell was discovered at White Moss Horticulture's 400-acre site in Kirkby, Liverpool after a peat-harvester ran over it.
"The harvest tractor unearthed the bomb but the driver couldn't see what it was, so he had a closer look," said White Moss Horticulture composting manager Paul Whyatt.
Army and Police explosives experts were called and destroyed the shell under a controlled explosion.
A Ministry of Defence spokesman confirmed that the bomb was "very old", possibly dating back to the Second World War.
Although it had been fired at some point, it was safe while sitting in the peat.
However, any movement was likely to trigger the device to explode.
White Moss Horticulture specialises in peat alternatives, blending peat with various products to create compost.
In February the company opened a £2 million green waste recycling centre with the capacity to turn up to 50,000 tonnes of green and wood waste into compost each year.
The facility and the company's composting operation have not been affected by the incident.