What happens when you dump 30 trucks full of coffee waste on land set aside for reforestation? Well, the forest recovers a heck of a lot faster, according to a study based in Costa Rica.


Researchers spread coffee pulp, a waste product of coffee production, across old agricultural land measuring 35 x 40m. The plot recovered four times faster than a control area. Talk about a caffeine boost.

"The results were dramatic," said Dr Rebecca Cole from the University of Hawai'i, 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."

Working with collaborators from the Swiss research university ETH-Zurich, Cole's team spread a layer of coffee pulp half a metre thick across the entire area. This eliminated the invasive grass species, allowing native trees to recolonise quickly, their seeds spread by wind and animal dispersal.

After two years area treated with coffee pulp had 80 per cent canopy cover compared to 20 per cent in the control area. The trees in the coffee pulp area were also four times taller and there were significantly higher levels of nutrients in the soil, including carbon, nitrogen and phosphorous.

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The study, conducted on land that underwent drastic deforestation in the 1950s, shows that cheap, readily available waste products can accelerate the recovery of tropical forests. It's useful intel as the world aims to restore large areas of forest, in line with in the 2015 Paris climate agreement.

Cole thinks that further research is needed because the study involved only a single site on flat land. "We would like to scale up the study by testing this method across a variety of degraded sites in the landscape," she said. "Also, this concept could be tested with other types of agricultural non-market products like orange husks.

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"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."


Reforestation is a major element in global plans to decarbonise the planet. In the UK, climate experts have advised the government to plant 1.5bn trees over the next 10 years to help the country meet its own climate targets.


A former deputy editor at Science Focus, Ian once undertook a scientific ranking of the UK's best rollercoasters on behalf of the magazine. He is now a freelance writer, which is frankly a lot less fun.