Living organisms (plants and certain microorganisms) absorb and convert CO2 into organic matter through photosynthesis and other biochemical pathways; this is called Biological Carbon Fixation (BCO2). Microbial carbon fixation by heterotrophs and autotrophs (MCO2) is a sub-category of this and refers to the fixation of CO₂ by microbes into usable organic substances by means of enzymatic reactions.
Explore the infographic from C-SINK partner ekolive to find out more about these processes.
For a more extensive overview of the technology, consult our factsheet.
Figure 1. BCO2 and MCO2 process.
TRIALS TO VALIDATE MICROBIAL HYDROCARBON FIXATION
As part of the C-Sink project, ekolive conducted several case studies on arable land in three Central European countries (Germany, Slovakia and Croatia) in 2024. The aim was to obtain reliable results on microbial carbon fixation by heterotrophic and autotrophic microorganisms in order to assess the potential and mechanisms by which microorganisms (can) contribute to carbon sequestration and storage in the soil.
The studies were carried out in Slovakia on raspberry and cereal (oat) fields, in Germany on red currants and blueberries, and in Croatia on vineyards. Each location was characterized by different climatic zones and soil types.
Figure 2. Field work in Rozhanovce/SK raspberries plot.
Microbial carbon fixation occurs naturally in healthy soils – “healthy” means that the natural microbiome is present in its entirety and has not been impaired or even killed by agrochemicals. All microorganisms, both autotrophic and heterotrophic, fix CO2 and form two different forms of fixed carbon in the soil: (1) SIC (Soil Inorganic Carbon) – Inorganic carbon in the form of carbonates and (2) SOC (Soil Organic Carbon) – Organic carbon, in this case bound in microbial biomass.
SOC stands for short to medium-term carbon storage and is part of the biological carbon cycle. It plays a central role in soil quality and climate regulation. SIC is a long-term, i.e. geochemically stable carbon storage (persistence over thousands of years) and influences the pH value and soil fertility.
Figure 3. Adding the biostimulants to the irrigation system.
In order to determine the potential of microbial carbon fixation, the test plots were inoculated with up to 1,000 microbial species of natural heterotrophic and autotrophic microorganisms as well as microalgae in the form of liquid biostimulants (ekofertile® plant and microfertile® plant) from ekolive’s ETV-certified bioleaching process InnoBioTech®; the biostimulants thus served as microbial soil activity enhancers, so to speak.
Figure 4. First soil sample takings.
Soil samples were taken regularly throughout the growing season to determine the retention potential of the soil. In addition, soil samples were analysed to determine important parameters in comparison to control values that were collected simultaneously on untreated plots: Total organic carbon, total inorganic carbon, humus, pH, total nitrogen, phosphorus, potassium, magnesium, copper, C/N ratio and storage density. Finally, the effects on biological carbon fixation in the soil were monitored and compared on sprayed and irrigated plots as part of the C-SINK project.
The preliminary results show astonishing values. The example of the areas in Slovakia on which oats were grown shows that the SOC values in the soil increased by 60 % and the SIC values even by over 80 %. This also gives an indication of how farmers can additionally benefit in their own area: Increased sugar and protein content, faster crop development, disease resistance, drought resistance, increased yield and profit with low investment per hectare, and increased efficiency of agrochemicals.