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News Article

Trade-offs between shaded and full-sun cocoa


Optimisation of productivity costs and ecological benefits of shade cocoa farming uncovered

Chocolate consumption has been on an upward slope for decades and demand shows no sign of slowing. But obtaining higher yields represents a great challenge for many smallholders in the face of increased disease and pest problems as well as ever decreasing soil fertility. The goal for many therefore is to at least maintain yields and hopefully increase them.

Cocoa was first cultivated as a shade crop, underneath the canopies of native trees. However, higher-yielding, full-sun monocultures eventually superseded this as pressure to produce higher and higher yields increased. The presence of shade trees provides direct competition for nutrients and prevents light from reaching the crop so therefore the removal of these constraints makes sense in order to maximise profit.

But scientists and environmentalists alike are beginning to realise the error of this switch for the ecology of cocoa plantations. Shade cultivation is now being shown to provide benefits for biodiversity, soil fertility and carbon absorption. Shade trees help regulate temperature and humidity around the crops and are able to help keep harmful organisms in check. In these heterogeneous environments, diseases spread less quickly, and fluctuations in temperature can be buffered by shade, creating more stable yields over time.

Johan Six, research group head: "More ecology can make farming more sustainable and more stable."

Given the strong case for both types of farming it is surprising then that there has been little research on the relative trade-off between the two and how the costs and benefits weigh up. A paper published by researchers at the Sustainable Agroecosystems group at ETH Zurich has sought to remedy this; by comparing shaded and unshaded cocoa plantations in Ghana in order to establish the optimum point for compromise. And the results have uncovered just that; at around 30% shade coverage yield is not yet affected by the shade trees but the numerous ecological benefits they provide are all present.

Wilma Blaser, lead author: Thanks to our research on shade trees, we were able to put forward specific recommendations for the optimum degree of shade in cocoa farming."

This includes maintaining soil moisture and controlling pest and disease occurrence. This was a higher threshold than the researchers had expected and has the possibility to be increased further under correct management.

Wilma Blaser: "Targeted application of fertiliser, timely pest control, regularly pruning, or weeding could potentially increase cocoa yields even under a higher shade canopy."

Across the dataset 38 species of shade tree were found which were diverse in form and function, providing an avenue for further research into how shade-farming can be greater refined in order to maximise ecological harmony and productive output.

 

To read the full article see the citation below:

W. J. Blaser, J. Oppong, S. P. Hart, J. Landolt, E. Yeboah, J. Six. Climate-smart sustainable agriculture in low-to-intermediate shade agroforests. Nature Sustainability, 2018; 1 (5): 234 DOI: 10.1038/s41893-018-0062-8

Original press release: https://www.ethz.ch/en/news-and-events/eth-news/news/2018/05/optimum-shade-for-cocoa.html

 

To find >500 similar papers use the search string below in the Forest Science Database:

("cocoa" OR "Theobroma cacao”) AND ("shade trees" OR "shade plants" OR "shading" OR "shade")

Article details

  • Author(s)
  • Ellen Baker
  • Date
  • 11 June 2018
  • Subject(s)
  • Agroforestry