Hand pollination of cocoa flowers as a sustainable method to improve the income of cocoa farmers
Handpollination of cocoaflowers - an field experiment
In November 2018, the Göttingen-based agroecologists Dr. Thomas Cherico Wanger and Manuel Toledo Hernandez (meanwhile both at Westlake University of China) visited AMAP Brazil and Fazenda Bom Pastor for the first time. Together we wanted to discuss cooperation on cocoa research and outline project ideas. This was to be the start of the EAI-Project, but it could only be realized in 2022 due to the Covid pandemic. However, as we had already come together on site and didn't just want to plan theoretically, we decided to implement a small, exciting project that would only take a few months - from the cocoa blossom in November to the harvest of the cocoa fruit in the middle of the following year. This resulted in a scientific article that was published in 2023.
In a field experiment, an attempt is being made to optimize yields by hand-pollinating cocoa flowers. Cocoa flowers are pollinated by wild insects. Ecological conditions for pollinators on plantations are crucial for pollination success. Nevertheless, even with good ecological conditions, there is a gap between realized yield and potential yield. This yield gap is reduced on conventional cocoa farms with synthetic fertilizers and pesticides; this is not possible with organic management and also harms potential pollinators and biodiversity.
Hand pollination is a method for organic intensification of cocoa production. Here, the question of how many flowers of a tree have to be pollinated in order to achieve an optimal increase in yield is investigated. The amount of additional labor required and the extent to which the increased yield compensates for the increased labor are also recorded. On five different experimental plots, 0, 20, 50, 80 or 100% of the flowers are hand-pollinated respectively. Hand pollination is performed independently by our workers. The method is easy to perform and thus transferable to any other farm after a short introduction.
This first cacao project is being carried out by Göttingen scientists from the Institute of Agroecology and funded by AMAP, and aims to help improve the profitability of cacao farms and thus ensure the continued existence of cabrucas, which is particularly important for the long-term conservation of the last Mata Atlântica fragments. The cabruca system is the only traditionally successful agroforestry system that both maintains biodiversity and provides income for local farmers. Cabrucas act as corridors connecting relict forests and in turn serve as habitat for the fauna and flora of the Mata Atlântica.
The experimental design is conducted under a shade gradient from high shade of the cacao trees to low shade of the trees. Increased solar radiation increases the physiological stress of the cacao trees and thus reduces yield. Our project aims to show that the effect of yield increase by hand pollination is greatly reduced when physiological stress is high. Thus, ecological intensification would only be useful in natural agro-systems such as the cabruca system of Bahia and unsuitable for increasing yields for unshaded cocoa plantations such as those found in Ghana or Côte d'Ivoire.
For two months, the flowers are pollinated daily by hand and the fruiting was documented. All farm workers of AMAP were involved in the experiment and were trained by Dr. Wanger and Dr. Hernandez. Until the final fruit ripening about 5 months after pollination, the experimental plots were checked regularly.
In 2023, the handpollination project culminated in the publication of an scientific article.
The results of this field experiment shows an average yield increase of 300% per tree by enhancing pollination by 10 % of flowers per tree compared to the control (only natural pollination). 5 to 15 minutes of hand pollination per tree can substantially enhance the fruit set and number of mature fruits in low and high shade management. With this field experiment we can recommend performing hand pollination as method for increasing yields, particularly in agroforests under 40-50% canopy cover to create win-win opportunities for high productivity and climate resilience/biodiversity conservation.
