Blog Post

Three of FENIX’s partners are conducting field tests with our biochar-digestate mixture produced at TerraWatt. UGR, INRAE, and ELGO will collect soil samples, applying our biochar-digestate mixture to test how it affects the soils’ nutrient composition. Our partners will compare samples both before and after applying the biochar-digestate mixture to track their differences and evaluate the benefits of our soil enhancer product.

The soil samples will be analyzed for organic carbon and nitrogen dynamics, as well as the balance of greenhouse gases. To support this, a RothC Model will be implemented. This is a mathematical model that simulates soil’s organic carbon over time and will be used to assist our partners as they assess the residence time of organic carbon and track carbon and nitrogen dynamics in the soils.

Furthermore, the application of the biochar-digestate mixture will be tested to see how it affects nutrient leaching and soil erosion. To do this, an additional experiment simulating rainfall will be conducted within plots in Spain. These plots are in an area with a high-risk of soil erosion. Here, changes in soil properties will be assessed in relation to the different treatments applied, and to different rain intensities. The key variables here will be the slope of the land and its plant cover.

Soil and runoff will be assessed as follows:

• Runoff and sediment measurement: Monitoring sediments generated in the plots before and after biochar-digestate application, under varying rainfall intensities and durations.
• Sediment analysis: Evaluating texture, organic carbon and nitrogen content, available phosphorus, cation exchange capacity, and carbon fractions, thus enabling the quantification of total and stable carbon losses.
• Runoff water analysis: Measuring soluble organic matter and macro- and micro-nutrient concentrations.
• Soil erosion and nutrient leaching calculations: Derived from data collected during the rainfall simulations.

We look forward to sharing updates on our findings and the potential of the biochar-digestate mixture to improve soil health and sustainability.

Follow us on Linkedin to keep updated.

By: G. Carlson
Editorial: L. Salinas
October 2025