Our blog has been a little quiet during the beginning of this year as we were fully focussing on implementing our first pilot. Since the 1st of January, we were working on taking our idea to the field. In this blog post, we want to take some time to share our intense but successful first weeks of this year. At this point, we also want to take the opportunity to thank everyone who supported our mini-crowdfunding campaign last year. Thanks to you we even passed our funding goal by 100€!
Our first pilot project in São Paulo!
The first challenge we had to overcome was finding a pilot area where we could apply our rock powder. Luckily this was very easy as we onboarded our first partner in December 2021. When we presented our idea to Paula and Valter from PRETATERRA, they did not hesitate one moment and offered their property for our very first pilot project. Since 15 January, we have been on their farm in Timburi, São Paulo State, supporting the implementation of a 2ha agroforestry system. Knowing the location, we were able to take the next two crucial steps: Getting biochar and rock powder to the farm!
Sourcing suitable rock powder
In regard to rock powder, we identified various possible sources throughout Brazil. In fact the organic institute of Brazil has created a map where they show a variety of certified sources for rock powder in the country. We are currently analyzing those sources and will share a map of the carbon removal suitability of these rocks in a future post. Just next to the farm of PRETATERRA, the company REMINER was the closest source of rock powder. They produce this powder based on residues from the production of gravel stone and other building materials and give it an extra grind to accelerate weathering and accessibility of nutrients to the plants. We will visit the facility later this month to take a close look at their mining and production processes. Even though their material was not optimal in terms of carbon removal potential we picked it due to the low delivery distance. Using the equations from Renforth 2012, we conservatively calculated a potential 0.5 tCO2 that will be removed through the application of 10 tons of our rock powder (see equation 5 of the paper and compare our rock powder properties). After an LCA according to Lefebvre et al. 2019, we were happy to see that even with this nonoptimal material we will potentially remove significantly more carbon than we emitted through the application, with at least 80% of the removed CO2 representing net removal.
Sourcing suitable biochar
With regard to Biochar, we discovered that the Brazilian market is still in its infancy. Throughout Brazil, we identified only two biochar producers that work with a certified pyrolysis process. Moreover, these two producers were located at a distance and sold their products at a price that did render a collaboration for the pilot unfeasible. To keep the carbon footprint as low as possible, we opted for using the leftovers from a nearby charcoal producer in Piraju. He delivered 5 tons of eucalyptus char in a somewhat diverse texture, with some parts more chunky and others more powder-like. We are aware that vegetable charcoal is not the same as biochar and that both materials show different permanences in the soil, however, for this pilot case the material was just fine, and the procurement brought interesting insights about the Brazilian biochar market. With a carbon content of 75% and a 100 years permanence of ca 50% of this carbon, we have captured an additional 6.8t of CO2 in the soil of our 2ha agroforestry system. 
Spreading the fertilizers on the field
For the spreading, we have used a small Massey Ferguson Tractor (MF 4300) with a 2-ton limestone spreader attached. We loaded two shovels of biochar and two shovels of rock powder for each spreading session. As only one tractor was available we needed to disconnect the spreader for each loading which resulted in each loading session taking between 20 to 30min time. The actual spreading of one load (1.5t rock powder with 0.2t of biochar) took only 15min. Optimally a second tractor would be used to load the spreader. After some initial challenges regarding the spreader’s disc rotation and tractor speed, we found a good setting that allowed us to spread the material mix on 4 agroforestry lines per load. Spreading consumed about 3.5l/h of diesel. As we have spread after an extended time without rain we noticed that the spreading resulted in the creation of a serious dust cloud. Thus, an application after a rain event or with a slightly humid material may be recommended, however, in terms of carbon removal through enhanced weathering this does not reduce the impact. Luckily, just after the spreading it started to rain, this way incorporating the rock powder into the soil where we want it from a nutrient perspective. Currently, we are waiting for the soil to dry up again so that we can start implementing the agroforestry system lines and plant the beautiful avocado, teak, banana, and mahogany seedlings that have just arrived.
To get a better impression of the pilot check out our video from Timburi and follow us on Instagram. If you are interested to learn more about carbon removal through natural fertilizers or wish to set up a project together, reach out!