In an effort to restore landscapes degraded by agriculture and deforestation, countries around the world have pledged to reforest millions of hectares through the Bonn Challenge. But reaching the 350-million-hectare goal by 2030 will take strategic planning and efficient methods. Findings from a new case study show one of those methods could involve turning food waste into a reforestation accelerator.
Work published in Ecological Solutions and Evidence has shown that locally sourced nutrient-rich coffee pulp—an often discarded by-product of coffee production—can jump start forest regrowth. “This case study suggests that agricultural by-products can be used to speed up forest recovery on degraded tropical lands,” said lead author Rebecca Cole in a press release. “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 focused their restoration efforts on degraded pasture land in southern Costa Rica. The area had previously been used as agricultural and pasture land for coffee production and had undergone heavy deforestation, which started in the 1950s. Almost all of the study area was covered with introduced non-native pasture grasses.
To test its reforestation potential, the research team covered an area roughly the size of an ice hockey rink with 30 dump truck loads of unprocessed coffee pulp in early 2018. Over the next two years they measured soil composition, vegetation coverage and tree growth in the pulp-covered plot as well as an adjacent, pulp-free plot.
The differences were striking. Compared to the pulp-free plot, the study plot showed improved soil quality, increased plant diversity and four times more canopy cover. Early-emerging trees and shrubs had grown 20 to 30 times in stem density and diameter, respectively. Additionally, grass cover was nearly eliminated after pulp treatment and replaced with herbs and forest litter.
Though the results of this case study were noteworthy, the authors say more studies of this kind are needed, both to reassert their results and to test other types of agricultural waste fertilizers and different climates. By strategically pairing agriculture industries with reforestation efforts, both sides could reap the benefits.
Source: Cole, R.J. and Zahawi, R. A. Coffee pulp accelerates early tropical forest succession on old fields. Ecological Solutions and Evidence. 2021