When coffee is harvested, the skin and pulp are often discarded. Costa Rica, which has cut down much of its rainforest for agricultural purposes, 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.

Coffee beans do not grow like vines or beans. The coffee beans look like "cherries", they have skin and pulp inside which are the precious beans. Before they can be fermented in water, they are passed through a machine that extracts the grains. New research suggests that pulp, which is usually discarded, could help restore tropical forests.

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Researchers at ETH-Zurich and the University of Hawaii have discovered that this coffee-making waste is a fantastic growth agent. They tested it on some agricultural land in Costa Rica.

"The results were dramatic," said study lead author Rebecca Cole. "The area treated with a thick layer of coffee pulp turned into a small forest in just two years."

The researchers delivered 30 trucks full of coffee pulp on a 35-by-40-meter lot on the Sabalito Biological Reserve in Coto Brus County, Costa Rica. The land, which was part of a coffee plantation, is being reforested. Since 1950, Costa Rica has experienced rapid deforestation, followed by coffee cultivation and agriculture, which has led to a 25% loss of natural forest cover by 2014.

The pulp of the coffee helps to restore the forests

Before spreading the coffee pulp in a layer half a meter thick, the researchers measured the nutrients in the soil. They also cataloged the species that live nearby and took into account the size of the wood stems present. Forest cover was recorded, and drones were sent into the air to capture the amount of cover.

Credit photo: Unsplash

At the end of the two years, the control area had forests that covered over 20% of its area. In contrast, 80% of the land treated with coffee pulp had trees four times taller than those in the control area. The researchers analyzed nutrients in the soil and found significant levels of carbon, nitrogen and phosphorus, all vital nutrients.

Agricultural by-products should be used more

The researchers found that the coffee pulp removed invasive pasture grasses that inhibited reforestation. Their removal facilitated the reappearance of tree species whose seeds were planted by wind dispersal or with the help of animals, according to Big Think.

"This study suggests that agricultural by-products can be used to accelerate forest recovery on degraded tropical lands. In situations where the processing of these by-products involves a cost for the agricultural industries, their use for restoration in order to meet the global reforestation objectives can be a happy scenario, ”says Rebecca Cole.

"More tests are needed to see if this strategy works in a wider range of conditions. The measurements we share are only from the first two years. Long-term monitoring would show how coffee pulp influences soil and vegetation over time. Additional tests can assess if there are any side effects, "says Cole