From boosting local job opportunities to improving biodiversity and capturing carbon, restoring deforested land can hold a variety of benefits for both local communities and the environment. And in the tropics, these benefits could be boosted with the help of coffee waste — at least that’s what a recent study in Costa Rica points to.

Conducted by researchers from ETH-Zurich and the University of Hawaii, the study found that coffee pulp, a byproduct of coffee production, can be used to accelerate tropical forest recovery on post-agricultural land.

As part of the study, the researchers unloaded 30 truckloads of coffee pulp on a 35 by 40-meter area of degraded land that was previously a coffee farm. The team then marked out another area, similar in size, as a control group without coffee pulp.

“The results were dramatic,” said Dr. Rebecca Cole, 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.”

Only two years after the beginning of the study, the coffee waste-treated area had an 80 percent canopy cover compared to 20 percent in the control area. The canopy was also four times taller than the control patch of land.

Not only that, the half-meter thick layer of coffee pulp eliminated the invasive pasture grasses, which are often a barrier to successful forest recovery. Their removal allowed native, pioneer tree species to reemerge in the area at a faster rate, with the help of seeds dispersed by animals.

What’s more, the researchers also found that nutrients, including carbon, phosphorous, and nitrogen, were significantly higher in the coffee waste-treated area. This finding is particularly important since degraded land typically features low-nutrient soil which can significantly stagnate forest succession.

The study suggests that, as a widely-available waste product rich in nutrients, the coffee pulp can provide a double-edged, cost-effective solution to the climate crisis by aiding forest restoration.

“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,” said Dr. Cole.