The Orange Peel Experiment

Here in Guanacaste Province, less than two hours drive from Playa Potrero, is a remarkable site with an amazing story. The  Área de Conservación Guanacaste is one small part of the Parque Nacional Guanacaste (Guanacaste National Park.) A seven acre plot of land in this conservation area was the site of a very unique experiment that had amazing results-The Orange Peel Project.

The Orange Peel Project was the brainchild of 1976 University of Pennsylvania graduate husband and wife ecologists Daniel Janzen and Winnie Hallwachs. This couple worked for many years as researchers and technical advisors at Área de Conservación Guanacaste. They spent their later years focused on trying to preserve endangered tropical forest ecosystems for the future.

The year was 1997. Janzen and Hallwachs approached Del Oro, a large orange juice manufacturer that had just begun producing juice at a factory near the northern border of Área de Conservación Guanacaste. They offered the juice maker a deal-If Del Oro would donate part of its forest land to the ACG, the company could dump orange peel and pulp waste on degraded and deforested land that had been used as pasture within the national park for the purpise of biodegradation and soil enrichment.

Recognizing a good deal when they saw one, Del Oro quickly signed an agreement with the necessary stipulations, including that the peels and pulp be thoroughly rinsed to remove all traces of any acids that would be harmful to the landcscape. Over the course of one year, 12,000 metric tons of orange peels and pulp were trucked to and unloaded on the degraded land. This is when the problems began.

A rival citrus producer in Costa Rica known as TicoFruit sued Del Oro, arguing that Del Oro had “defiled a national park.” This case would eventually be decided in TicoFruit’s favor by the Costa Rican Supreme Court, and the orange peel and pulp covered land was completely forgotten for the next fifteen years or so.

Enter Timothy Treuer, a graduate student in Princeton’s Department of Ecology and Evolutionary Biology. During the summer of 2013, Treuer was discussing avenues of research with Daniel Janzen and the site in Costa Rica was mentioned. Treuer was intrigued and asked Janzen if any follow up ecology studies had been conducted. Janzen responded in the negative, noting that only taxonomists had visited the area to classify the local biological diversity. There had been no thorough follow up studies or evaluation. While performing other research in Costa Rica, Treuer stopped to visit the site to see how thijngs had changed.

“It was so completely overgrown with trees and vines that I couldn’t even see the 7-foot-long sign with bright yellow lettering marking the site that was only a few feet from the road,” Treuer said. “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.”

Treuer would comprehensively study the area with Jonathan Choi, who, at the time, was a senior studying ecology and evolutionary biology at Princeton. Choi would ultimately turn the project into his senior thesis.“The site was more impressive in person than I could’ve imagined,” Choi said. “While I would walk over exposed rock and dead grass in the nearby fields, I’d have to climb through undergrowth and cut paths through walls of vines in the orange peel site itself.”

Ultimately, after careful study and comparison with untreated land nearby, the researchers discovered dramatic differences between the areas that had been covered in orange peels and those that were not. The area fertilized by the orange waste had much more nutrient rich soil, significantly more tree biomass, a greater richness of tree-species and larger forest canopy closure above the site. “This is one of the only instances I’ve ever heard of where you can have cost-negative carbon sequestration,” said Timothy Treuer. “It’s not just a win-win between the company and the local park — it’s a win for everyone.”

This unique story has many potential implications for the future of how the environment could possibly be edified by recycling food waste under the right climate conditions for optimal biodegradation-and it all happened right here in our backyard in Guanacaste Province.

A huge thank you to the University of Princeton for the follow up article and study which can be found at this link: