LONDON - Coffee pulp could be a secret weapon in reviving tropical forests on deforested land, scientists have discovered.  

Spreading coffee pulp, a waste product of coffee production, onto deforested, degraded farmland can turbocharge forest regrowth dramatically, the team from ETH-Zurich and the University of Hawaii said.  

In 2018 researchers spread 30 dump truck loads of coffee pulp on to about one third of an acre of degraded farmland in Costa Rica, in an area that was tropical forest until the 1950s. They also marked out a similar sized area of the nearby land which did not receive the coffee pulp treatment.

Two years later, they returned to find tropical canopy covering 80 per cent of the coffee-treated land. “The results were dramatic” said Dr Rebecca Cole, lead author of the study. “The area treated with a thick layer of coffee pulp turned into a small forest in only two years while the control plot remained dominated by non-native pasture grasses.”

The scientists believe that the layer of pulp helped prevent non-native grasses from taking root in the soil, giving native trees the chance to take hold and flourish.  The coffee-treated land was also much richer in soil nutrients such as carbon, nitrogen and phosphorus, the team found.  

Although further research is needed, Dr Cole said the discovery could offer a “win-win scenario”, giving coffee producers an extra revenue source and “jump start” the growth of forest recovery on land cleared for farming.

“We hope our study is a jumping off point for other researchers and industries to take a look at how they might make their production more efficient by creating links to the global restoration movement,” she said.