Can Dynamic Agroforestry reverse the negative impacts on soils of long-time pineapple production and simultaneously create beneficial growth conditions for the delicate cocoa trees? A Swiss pioneer wanted to find out and four years ago installed a 50-ha plantation in Côte d’Ivoire. There, everything is managed according to the principles of Dynamic Agroforestry – a perfect playground for two motivated master students!
Conventional monocultures are problematic
The demand for chocolate is increasing worldwide and the chocolate’s main ingredient, cocoa (the fruit of Theobroma cacao L.), is the economically most important crop of Côte d’Ivoire. Cocoa exports support the livelihoods of nearly three quarters of the county’s rural population. But the production in monocultures, as it is the common practice, comes with major disadvantages. These include massive deforestation, loss of biodiversity, soil degradation and erosion, or carbon emissions. Projected climate change in West Africa seems to aggravate problems of cocoa value chain’s sustainability.
In contrast, agroforestry is claimed to have opposite effects, as it helps to maintain favourable soil conditions and reduces erosion and leaching, harbours higher biodiversity, buffers climate extremes, and reduces pest and disease pressures (or example reducing the severity of cocoa swollen shoot virus disease as shown by our supervisor Dr. Christian Andres). The so-called Dynamic Agroforestry specifically includes vertical canopy stratification and, through periodic heavy pruning and mulching, a high carbon turnover and soil amelioration.
Exploring new ways of production Fredy’s Plantation
Can Dynamic Agroforestry thus be a sustainable alternative to cocoa monocultures? Fredy Hiestand, a pioneer from the bakery industry in Switzerland, wanted to know and installed a large-scale, mechanised cocoa plantation in Tiassalé, Côte d’Ivoire (explore the site). His intention: to produce organic, eco-friendly chocolate for his own “Schoggi-Gipfeli” (chocolate croissants). Despite the massive organisational and manual efforts, production lags expectations and aspirations, and cocoa performance leaves much to be desired in many areas of the plantation.
At this point, our Master’s thesis came in. During a three-month stay, we searched to answer two major questions: With Liebig's Law in mind, we tried to find one or two causes defining the vigour of cocoa trees, so that with one or two simple changes in management, cocoa could be supported. Secondly, we wanted to know if the soil amelioration through the regular pruning and mulching did already bear fruit.
Progress already visible on large-scale Dynamic Agroforestry plantation
And we did find surprisingly positive results: On the four-year-old cocoa plantation, the Dynamic Agroforestry with its high biomass turnover already led to detectable changes in the soil: there were significantly higher nutrient concentrations in the soil, which also tended to be not that dense anymore, and capable to hold more water. And even better: cocoa trees seem to benefit from these soil changes, as they grow more vigorously on spots where there are increased levels of nutrients, less compact soils and higher water holding capacity. Besides the very promising results from the soil analysis, what really struck us the most was the diversity of plants, birds and bugs as well as the calm and comfortable atmosphere. While on nearby monocultures of cocoa the African heat was as unpleasant as in the inner-city circles of Abidjan, on Fredy's Plantation everything was different. Here, temperatures under the relieving shade were bearable and the sound of many different insects and birds in combination with the wind caressing through the canopy came close to the Garden of Eden.
Water and climate change remain major challenges
On the plantation, one factor seemed most determining for plant growth: plant available water. Precipitation amounts in the region are very much below recommended values, while climate models project less precipitation and higher temperatures during future dry seasons, thus aggravating potential drought stress (learn about why it is too hot for chocolate and how more complex interactions are affected). Observations and impressions from the field led to the conclusion that small-scale water availability creates a pattern of lower and higher plant vigour within the plantation landscape. A correlation of low water availability and low vigour areas supports this assumption (learn more about the correlation between soil conditions and plant vigour here). However, with our Swiss perspective on trees, we were amazed by what seems possible on these very dense soils, were we could not even penetrate with a simple TDR-device that measures soil moisture. Trees at an age of only four years already had a diameter of 25 cm. In Switzerland, it takes 20 to 30 years to get there!
One step towards sustainable cocoa production
Our results show that despite initial difficulties, Dynamic Agroforestry is able to produce the promised effects on soil on an industrial scale and in a very short time (only four years). But a climate- and region-adapted plant mixture is crucial for every functioning (agro-)forestry system. If the benefits of Dynamic Agroforestry are large enough for economically sustainable cocoa production in a region with adverse climate and climate projections, remains to be seen.
Dynamic Agroforestry is a highly complex system with countless interactions between all the different plant species. For an optimal management, this needs a very deep understanding and close and constant monitoring of the natural processes. Counselling and assistance would mean that one expert (specifically Dynamic Agroforestry) agronomist is on the plantation the whole year. Unfortunately, this was not the case and at management level, the idea of dropping the whole project came up repeatedly. Without a very sound project management and a competent, well-coordinated, and harmonious leadership team, visible progress in the field can be ruined and even the largest investments will not lead to success. During our Master’s thesis, we also had to realise that constructive cooperation and teamwork are the be-all and end-all for success.
Originally it was not planned that we would write a single work together, but that everyone would work on their own topic. Our supervising professor was also very sceptical about this close cooperation. But since we collected all the data in the field together and always helped each other, the two main topics moved ever closer together. In the end, we worked so closely that two separate projects would no longer have made sense. Thus, we became an invincible dream team and we could constantly motivate and support each other!
A good teamwork was especially relevant in the challenging environment that we were faced with. Not only the tropical climate and always spicy food, but also cultural differences and personal worries were easier to endure with a good friend by one’s side.
ABOUT THE AUTHORS
Katja Degonda and Severin Wiens are two enthusiastic Master’s students at ETH Zurich. Their interests cover a wide range with one overall topic in mind: carbon sequestration for climate change mitigation. From food and agriculture to soil, from forestry and landscapes to agroforestry, and from woody biomass to biochar and organic fertilisers; they love to explore complex systems and their management for a healthier planet.