Could Orange Peel Be The Secret To Reviving Lost Forests?


Katy Evans

Katy is Managing Editor at IFLScience where she oversees editorial content from News articles to Features, and even occasionally writes some.

Managing Editor


Four and a half years after the orange peel was spread the forest went from 23 recorded plant species to 123. (c) Daniel Janzen and Winnie Hallwachs

Don’t you hate it when other people are right? Well sometimes, but when they’re right and the whole world benefits, then it’s a lot easier to swallow.

This is a story of how researchers came up with a novel idea for disposing of waste as a biodegradable fertilizer. They managed to convince execs at a company to trial this, but were hampered when another company got in involved and sued the first company for littering. Now, 16 years later, the disregarded area of forest “littered” with biodegradable waste is a thriving, verdant, successful habitat. The miracle cure/offending item? Orange peel.


In the mid-1990s, Daniel Janzen and Winnie Hallwachs, ecologists at the University of Pennsylvania, were working for the Guanacaste Conservation Area in Costa Rica to ensure the future of endangered tropical forest ecosystems.

They approached orange juice manufacturer Del Oro, who had just set up camp down the road, with an idea for a mutually beneficial exchange. If Del Oro donated part of its forest land to the conservation area, they would allow it to dispose of its orange peel waste, which is biodegradable, on the land for free.

At the time, Del Oro produced around 12,000 metric tonnes of orange peel waste a year, so it was a pretty good deal.

1,000 trucks of orange peel (c) Daniel Janzen and Winnie Hallwachs

But a year later, rival company TicoFruit sued Del Oro for having "defiled a national park". It went to Costa Rica’s Supreme Court and TicoFruit won. The barren pasture of national forest was then largely forgotten by both companies and the Guanacaste Conservation Area.


Then in 2013, researchers from Princeton’s Department of Ecology and Evolutionary Biology got talking to Janzen about possible research sites and the forgotten area was mentioned, so they went to visit it.

18 months after the orange peel, 81 species of plant were found instead of the initial 23. (c) Daniel Janzen and Winnie Hallwachs

"It was so completely overgrown with trees and vines that I couldn't even see the 7-foot-long [2-meter-long] sign with bright yellow lettering marking the site that was only a few feet from the road," co-lead author Timothy Treuer said in a statement. "I knew we needed to come up with some really robust metrics to quantify exactly what was happening and to back up this eye-test, which was showing up at this place and realizing visually how stunning the difference was between fertilized and unfertilized areas."

Their study, published in Restoration Ecology, revealed an amazing 176 percent increase in biomass in the 3-hectare (7-acre) area studied. The difference between forest covered in orange peel and that which was not was huge. The orange peel-covered soil was richer, there was more forest canopy closure, and a greater number of tree species.

Not only did the agricultural waste revive the forest, it sequestered a serious amount of carbon, all for free.  


“This is one of the only instances I’ve ever heard of where you can have cost-negative carbon sequestration,” said Treuer. “It’s not just a win-win between the company and the local park – it’s a win for everyone.”

Which goes to show, those researchers were right back in the ‘90s, and they’re still right now.

“Plenty of environmental problems are produced by companies, which, to be fair, are simply producing the things people need or want,” said study co-author David Wilcove. “But an awful lot of those problems can be alleviated if the private sector and the environmental community work together. I’m confident we’ll find many more opportunities to use the ‘leftovers’ from industrial food production to bring back tropical forests. That’s recycling at its best.”


  • tag
  • endangered,

  • forest,

  • costa rica,

  • orange peel,

  • del oro,

  • ticofruit,

  • biodegradable fertilizer,

  • agricultural waste