The recycling forest 3 years after coffee pulp was applied to the area. Credit: Rebecca Cole.
A new study has found that coffee pulp, a waste product of coffee production, can be used to accelerate tropical forest reclamation on agricultural land. The findings are published in the British Ecological Society magazine Ecological solutions and evidence.
In the study, researchers from ETH-Zurich and the University of Hawaii indicated 30 trucks of loads of coffee pulp on a 35 × 40 m area of degraded soil in Costa Rica and a similar-sized area without coffee pulp as a control.
“The results were dramatic.” the dr. Rebecca Cole, lead author of the study, said. “The area treated with a thick layer of coffee pulp has turned into a small forest in just two years, while the control site remains dominated by non-native pasture grasses.”
After only two years, the treated area with coffee pulp had 80% canopy, compared to 20% in the control area. The canopy in the coffee pulp area was also four times higher than the control area.
The addition of a half-meter-thick layer of coffee pulp eliminated the invasive pasture grasses that dominated the land. These grasses are often an obstacle to the succession of the forest and by removing them, native pioneer tree species, which arrived through the spread of wind and animals, can quickly recolonize the area.
The researchers used 30 trucks of coffee pulp to start forest revival. Credit: Rebecca Cole.
The researchers also found that nutrients, including carbon, nitrogen and phosphorus, were significantly increased after two years in the treated area with coffee pulp compared to the control. This is a promising finding, as former tropical agricultural land is often very poor and that the poor quality of the forest can delay the succession of the forest for decades.
Dr Cole said: ‘This case study suggests that agricultural products can be used to accelerate forest reclamation in weakened tropical countries. In situations where the processing of these by-products incurs a cost to agricultural industries, it can be a win-win scenario if used for recovery to achieve global reforestation targets. ‘
As a widely available waste product with many nutrients, coffee pulp can be a cost-effective forest restoration strategy. Such strategies will be important if we are to achieve ambitious global goals to restore large forest areas, such as those agreed in the 2015 Paris Agreement.
The study was conducted in the province of Coto Brus in southern Costa Rica on a former coffee farm that is being restored for conservation in the forest. In the 1950s, the region underwent rapid deforestation, and the conversion of land to coffee farming and grazing with forest cover decreased to 25% by 2014.
The difference between the coffee pulp and the control premises after 1 year. Credit: Rebecca Cole
In 2018, the researchers set out two areas of approximately 35 × 40m, spreading coffee pulp in a half-meter-thick layer on one area and leaving the other as a control.
The researchers analyzed soil samples for nutrients immediately before administering the coffee pulp and again two years later. They also recorded the species, size of woody stems, percentage of forest floor cover and drones to take up canopy canopies.
Dr Cole warns that as a case study with two years of data, further research is needed to test the use of coffee pulp to promote forest recovery. ‘This study was conducted in only one major area, so more testing is 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 will show how the coffee pulp has affected soil and vegetation over time. Additional tests can also determine if there are unwanted effects of administering coffee pulp. ”
The limitation of the use of coffee pulp or other agricultural products is that their use is mostly limited to relatively flat and accessible areas where the material can be delivered and that the risk of the added nutrients being flushed into the nearby water separations is managed.
Regarding further investigation into the use of coffee pulp, dr. Cole said: “We want to expand the study by testing this method on a variety of backward areas in the landscape. This concept can also be tested with other types of agricultural products, such as orange peels, in agriculture.
“We hope our study is a starting point for other researchers and industries to look at how they can make their production more efficient by creating links to the global recovery movement.”
Reference: “Coffee pulp accelerates early tropical forest succession on ancient fields” by Rebecca J. Cole and Rakan A. Zahawi, March 28, 2021, Ecological solutions and evidence.
DOI: 10.1002 / 2688-8319.12054