How your daily coffee can help tropical forests grow back

Researchers find that the coffee pulp is valuable in its own right.

How your daily coffee can help tropical forests grow back

A dog relaxes next to a new forest area, courtesy of coffee-pulp

Credit: Rebecca Cole/British Ecological Society
  • When coffee is harvested, the skin and pulp surrounding the bean are often discarded.
  • Costa Rica, which had much of its tropical forests chopped down for agricultural use, is testing coffee pulp as a way to help reforest the country.
  • A new study finds that coffee pulp can help reforest land in just two years.

    The coffee beans that keep us going don't grow on the vine in bean form. They grow as coffee "cherries," skin and pulp inside of which resides the precious beans. Before coffee beans can be fermented in water as many are, the cherries pass through a machine that extracts the bean from the skin and pulp. Miraculous as coffee beans are, new research suggests that their typically discarded pulp is even more amazing. It can restore tropical forests.

    Researchers from ETH-Zurich and the University of Hawaii have found that this waste from coffee manufacturing is a fantastic growing agent after testing it out on some agriculturally depleted land in Costa Rica.

    "The results were dramatic," reports lead author of the study Rebecca Cole. "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."

    Pulp non-fiction

    Coffee pulp arrivesCredit: Rebecca Cole/British Ecological Society

    The researchers delivered 30 dump trucks full of coffee pulp to a 35- by 40-meter parcel on Reserva Biológica Sabalito in Costa Rica's Coto Brus county. The land, previously part of a coffee plantation, is in the process of being reforested.

    Starting in the 1950s, Costa Rica experienced rapid deforestation followed by coffee-growing and farming that resulted in a 25% loss of its natural forest cover by 2014.

    Before spreading out the coffee pulp into a half-meter-thick layer for their test, the researchers measured the nutrients in the soil. They also catalogued the species living nearby, and made note of the size of woody stems present. The amount of forest ground cover was recorded, and drones were sent aloft to capture the amount of canopy cover.

    Reforestation in the blink of an eye

    (A) Coffee pulp layer; (B) control area after two years; (C) coffee pulp area after two years; (D) overhead view of canopy in control area, above the red line, and the coffee-pulp area, below the red lineCredits: A, B, and C: R. Cole. D: credit R. Zahawi/British Ecological Society

    At the end of the two years, the control area had grown forest covering over 20% of its area. In contrast, 80% of the coffee-pulp section was canopied by trees, and these trees were four times the height of those in the control parcel.

    The researchers analyzed the nutrients available in the soil and found significantly elevated levels of carbon, nitrogen, and phosphorous, all vital agricultural nutrients. Curiously, potassium, also important for growth, was lower in the coffee-pulp area than in the control section.

    The researchers also found that the coffee pulp eliminated invasive pasture grasses that inhibit reforestation. Their removal facilitated the reemergence of tree species whose seeds were introduced by wind or animal dispersal.

    A much-needed growth agent

    According to Cole, "This case study suggests that agricultural by-products can be used to speed up forest recovery on degraded tropical lands. In situations where processing these by-products incurs a cost to agricultural industries, using them for restoration to meet global reforestation objectives can represent a 'win-win' scenario."

    Promising as coffee pulp may be, Cole cautions: "This study was done at only one large site, so more testing is needed to see if this strategy works across a broader range of conditions. The measurements we share are only from the first two years. Longer-term monitoring would show how the coffee pulp affected soil and vegetation over time. Additional testing can also assess whether there are any undesirable effects from the coffee pulp application."

    In addition, she notes, the experiment only documents the value of coffee pulp on flat land when delivery of the substance by truck is fairly simple. "We would like," Cole says, "to scale up the study by testing this method across a variety of degraded sites in the landscape."

    Just as exciting is the possibility that other such agricultural waste products may be good for reforesting depleted areas. Cole mentions orange husks as a material worthy of investigation.

    "We hope," Cole concludes, "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."

      From 1.8 million years ago, earliest evidence of human activity found

      Scientists discover what our human ancestors were making inside the Wonderwerk Cave in South Africa 1.8 million years ago.

      Inside the Kalahari Desert Wonderwerk Cave

      Credit: Michael Chazan / Hebrew University of Jerusalem
      Surprising Science
      • Researchers find evidence of early tool-making and fire use inside the Wonderwerk Cave in Africa.
      • The scientists date the human activity in the cave to 1.8 million years ago.
      • The evidence is the earliest found yet and advances our understanding of human evolution.
      Keep reading Show less

      How cell phone data can help redesign cities

      With the rise of Big Data, methods used to study the movement of stars or atoms can now reveal the movement of people. This could have important implications for cities.

      Credit: Getty Images
      • A treasure trove of mobility data from devices like smartphones has allowed the field of "city science" to blossom.
      • I recently was part of team that compared mobility patterns in Brazilian and American cities.
      • We found that, in many cities, low-income and high-income residents rarely travel to the same geographic locations. Such segregation has major implications for urban design.
      Keep reading Show less

      The never-ending trip: LSD flashbacks and a psychedelic disorder that can last forever

      A small percentage of people who consume psychedelics experience strange lingering effects, sometimes years after they took the drug.

      Credit Imageman Rez via Adobe Stock
      Mind & Brain
      • LSD flashbacks have been studied for decades, though scientists still aren't quite sure why some people experience them.
      • A subset of people who take psychedelics and then experience flashbacks develop hallucinogen persisting perception disorder (HPPD), a rare condition in which people experience regular or near-constant psychedelic symptoms.
      • There's currently no cure for the disorder, though some studies suggest medications may alleviate symptoms.
      Keep reading Show less
      Mind & Brain

      Mind and God: The new science of neurotheology

      Studies show that religion and spirituality are positively linked to good mental health. Our research aims to figure out how and why.