Coffee waste can help accelerate tropical forest recovery

In a new study published by the British Ecological Society, experts report that a widely available coffee waste product can be used to speed up the recovery of tropical forests that have been cleared for agricultural practices. 

For the investigation, researchers from ETH-Zurich and the University of Hawaii spread 30 dump truck loads of coffee pulp on degraded land in Costa Rica. The team also marked an untreated plot for comparison.  

“The results were dramatic,” said study lead author Dr. 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.”

In two years, the site treated with coffee pulp had 80 percent canopy cover compared to just 20 percent in the control area. In addition, the canopy in the coffee pulp area was four times taller.

The addition of coffee waste eliminated the invasive pasture grasses that dominated the land, allowing native trees to quickly become established.

Former tropical agricultural land is often very degraded with poor soil quality, which can delay forest recovery. The researchers found that nutrients including carbon, nitrogen, and phosphorous were significantly higher in the area treated with the coffee waste product.

“This case study suggests that agricultural by-products can be used to speed up forest recovery on degraded tropical lands,” said Dr. Cole..”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.”

The study was conducted in Coto Brus county in southern Costa Rica on a former coffee farm. Dr. Cole noted that further research is needed to test the use of coffee waste in forest restoration. 

“We would like to scale up the study by testing this method across a variety of degraded sites in the landscape. Also, this concept could be tested with other types of agricultural non-market products like orange husks,” said Dr. Cole.

“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.”

The study is published in the journal Ecological Solutions and Evidence.

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By Chrissy Sexton, Earth.com Staff Writer