Dr Mary Cole
Dr Mary Cole used the ashes of a late friend to find out if the process was possible Greater Melbourne Cemeteries Trust

The latest advances in recycling developed by Australian plant pathologists have made possible a way for remains of the dead to provide nourishing sustenance for trees and other plant life. One of the stumbling blocks to the process was finding a method to reduce the salt levels and high amounts of alkaline in human ashes, which are similar to caustic soda, killing plant life.

Scientists also had to work out a way round human ashes solidifying when mixed with water. "I would like to think that a person who lived for, say, 70 years and contributed to life on Earth becomes now a tree that might live for hundreds of years. So their spirit lives on in a tree," said Mary Cole, a Melbourne plant pathologist.

She said her research was "incredibly emotional", as she used the ashes of a late friend to find out if the process was possible.

Dr Cole carried out experiments initially on the ashes of animals, and then later on human beings. Her team eventually found a way to convert human ashes into plant food. The technique is under wraps at present, although they are applying for a patent.

The best trees to flourish when fed on a diet of human ashes were silver birches. In total, 16 tree species including Australian and European varieties were used in the experiments. Friends and relatives of people who die in Melbourne will be the first to be offered a tree fed by a loved one's remains.

Cole was approached by the founder of the memorial tree company Warren Roberts, who was coming to terms with the death of a close friend 10 years ago.

"It only takes about a 100 trees to offset all the breaths a human takes in their lifetime and we give back 200, and those trees are connected to that person's legacy," he told ABC.