Implementation at Volcán Azul

Implementation at Volcán Azul

At POMA, we conduct various experiments covering every aspect of coffee farming, with a particular emphasis on crop load management and growth regulation techniques, water- and fertiliser optimisation, and understanding how climate impacts quality and tree physiology. We do this in our Coffee Research Station in Denmark, which is a climate-controlled greenhouse facility where we manipulate environmental factors based on algorithms that mimic plant processes. This allows us to study how coffee trees react to climate change while also maintaining a stable environment for investigating the impact of farming practices. These efforts serve as the basis for developing innovative agricultural methods that can benefit coffee growers worldwide.

Once we document our findings, we conduct larger scale research on farm-level to verify the effects in a real-life production scenario. This year, we visited our partners at Volcán Azul to initialise our research trials on farm-level for the season 2024-2025.




VOLCÁN AZUL


Volcán Azul, managed by Alejo Castro Kahle, is situated on the fertile volcanic slopes of the Poás Volcano in Central Valley at altitudes ranging from 1400-1900 masl., complemented by a state-of-the-art mill. Alejo and his team are dedicated to maintaining and improving coffee quality, honouring their family's long legacy of outstanding coffee for several generations.

Their commitment extends to ongoing research into coffee varieties and innovative crop management techniques, driven by a desire to diversify and heighten the quality of their offerings, and adapt to Costa Rica's changing climate. Coffee is sensitive to weather changes, and threats from the changing weather pose significant challenges, which Alejo has witnessed firsthand. Despite these challenges, Alejo and his team remain determined. Their dedication to producing top-quality, resilient coffee reflects their strong commitment to sustainability, which is something we truly admire.


 

 



Their willingness to innovate and develop has been essential to our collaborative efforts, which has seen us initiate a lot of experimentation on their farm for the coming years. In December 2023, we visited Alejo and his team at Volcán Azul to discuss how we approach the trials for the coming years - and this journal serves as an insight into our thoughts and ideas. 

 

EXPERIMENTS 2024 - 2025


THINNING

In recent years, a lot of hybrid varieties have seen the light of day with the promise of high productivity and good quality in most coffee producing countries. However, when you boost productivity in coffee plants, it typically comes at the expense of quality due to internal competition amongst fruits, which has become very clear for the majority of these new varieties. Some examples for Costa Rica include Obata, H1, and Marsellesa. At the same time, coffee trees are quite prone to biennial bearing, where trees alternate between high and low yields, or even suffer from branch dieback due to overbearing, due to internal stresses and imbalanced carbon- and nutrient allocation in the plants.

 

In our research station, we investigated a technique called ‘thinning’ and its application under these conditions. Thinning is a crop load management technique that has been practised in modern-day fruit production for many years, which involves removing excessive fruit from the trees, with the potential to ensure consistency in yield and a higher fruit quality. By removing fruit we are able to ensure that the excess nutrients are diverted to the remaining seeds to have a higher concentration. These nutrients are essential for developing aroma compounds, which contribute to the intensity and complexity of this coffee.

 

Thinning has also proven effective in preventing biennial bearing by directing carbohydrates and nutrients to vegetative growth, thereby promoting the development of new fruiting wood for the next year. This not only improves harvest quality but also maintains consistent yields. While not commonly practised in coffee cultivation, we believe thinning shows promise for enhancing crop quality and yield stability.

 

In this experiment, we will manually remove coffee cherries in varying quantities from high crop load varieties such as Obata, H1, and Caturra during the seed ripening stage (June-July at Volcán Azul). This aims to optimise cultivation techniques for these new hybrid varieties, which require different approaches compared to more common varieties.


 

 



MICROCLIMATE

In some countries and regions, authorities have encouraged planting coffee trees in full sun-exposure to increase productivity. While this has some truth to it, as photosynthesis will be prompted to increase, it will be at the expense of quality as the seeds and fruit will mature and ripen too fast if temperatures are also high. In the end, cells will lack nutrients and sugars, and coffee quality will be suppressed. Additionally, excessive sunlight and heat can stress trees, particularly those adapted to shaded environments. However, coffee trees require adequate sunlight for vitality and productivity. Therefore, it's essential to strike a balance between sunlight and shade to promote both productivity and quality for different varieties.

 

Based on results from our research station, for the coming years, we will investigate the impact of altitude and shade, inducing lower temperatures and a lower oxygen pressure, on coffee tree vitality and coffee quality for some of Alejo’s most appreciated varieties such as SL28, Gesha, Ethiopian Landraces, and Caturra.

 

We also found some interesting relationships between synthesis of floral aroma compounds, such as terpenes, and the intensity of coffee aroma with higher altitude simulations, which we are keen to explore further on farm-level. 

 

 


PROCESSING


At POMA, we value innovation in processing methods, but we also believe in allowing the true essence of coffee to shine through without fermentation. That's why we've developed a unique processing method at our research station called the 'Cold Washed Process'. This method respects the tradition of the washed process while embracing innovation. You can read more about this process in our latest journal (‘Cold Washed Process’)

 

However, this process has some requirements that can be quite difficult for coffee growers to comply with. Initially, we subject coffee cherries to a cold storage period for 48 hours at 8C, which is often difficult due to climatic conditions at farms being too warm. With Alejo, our solution is to have running water going in circles around the tanks to cool them down. We tested this solution and found it effective enough to go ahead and experiment with.

 

We conducted experiments with varieties like SL28, Gesha, Caturra, and Ethiopian Landrace this season, yielding promising results that align with our hypothesis on aroma preservation and intensification. We plan to expand this processing method to more varieties in the upcoming season to further explore Alejo's coffee quality potential.

 

 



PRUNING

For a lot of fruiting crops that are freshly consumed (i.e. apples, pears), pruning practices have been studied and developed for many decades to ensure optimal eating quality and appearance. Since coffee is a processed product, less attention has been given to the apparent fresh quality of the fruit as it is not directly measurable in the field. 

One major discovery we did in the research station was that sap flow was greater in younger wood, emphasising growth and quality in these parts. Younger wood produced both higher quality fruits and seeds. Therefore, training coffee trees should focus on renewing old branches and promoting the growth of young, vital wood.

In the future, we will explore different pruning techniques to optimize coffee fruit and seed quality, aiming to develop a universal pruning system that is efficient and effective. This season, we will work with high-vitality varieties like Obata and Caturra to validate our pruning system's effectiveness.