Dumping Coffee Pulp To Forests Could Boost Recovery

The cup of coffee you occasionally enjoy in the morning leaves behind an abundant agricultural by-product: coffee pulp which is the coffee fruit without seeds or beans. Nowadays, most of this waste goes without treatment directly to huge waste disposal sites, and when dumped, it pollutes the environment in the coffee-producing regions, standing in the way of sustainability of the coffee supply chain.

Now, a new study, published in the journal Ecological Solutions and Evidence, has found that coffee pulp can be used to promote tropical forest recovery on post-agricultural lands, according to a press release. Since it is not only widely available but also high in nutrients, coffee pulp could provide immense benefits to forest restoration strategy. 

A transformation in two years

The findings are based on a study by the ETH-Zurich and the University of Hawaiʻi researchers. 30 dump truck loads of coffee pulp were spread on a 115 x 131 feet (35 × 40m) area of degraded land in Costa Rica and "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."

Researchers had also marked out a similar-sized area without coffee pulp as a control. In only two years, the area with the coffee pulp had 80 percent canopy cover compared to 20 percent in the control area. Moreover, the canopy in the first area was also four times taller than the other.

The area was dominated by invasive pasture grasses which prevent forest succession. It was seen that the addition of the 0.4-0.5 meters (1.31-1.64 feet) thick coffee pulp layer eliminated the invasive pasture grasses, allowing nature tree species to reclaim the area through winds and the carrying of the animals quickly. Nutrients such as carbon, nitrogen, and phosphorous were significantly more in the coffee pulp treated area.

"This case study suggests that agricultural by-products can be used to speed up forest recovery on degraded tropical lands." Dr. Cole explained. "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 researchers now want to scale up the study by testing the coffee pulp method across a variety of degraded sites in the landscape. Moreover, other types of agricultural non-market products like orange husks could also be tested.