Scientists have analyzed whether the planting of grasses and clover under solar panels can increase the organic carbon of the soil, after measuring the results of a commercial plant in Japan. They tested more than 20 areas in the power plant and discovered that the organic carbon of the soil increased.
Researchers at Kyushu University in Japan have studied whether planting grasses and clover under solar panels can increase the organic carbon of the soil (SOC).
“This research is new by laying a scientific basis for potential carbon credits,” emphasized the corresponding author Michiyuki Yagi in a conversation with PV -Magazine.
The scientists planted seeds under panels in a commercial plant and measured soc content in the soil with three different methods. “SOC is a particularly promising component for natural climate solutions (NCS) with a considerable mitigation potential,” they explained. “The carbon cycle includes interactions between the atmosphere, soil and plants. Plants absorb CO₂ through photosynthesis and then contribute to soc by residues who bother bodem microbes and return CO₂ to the atmosphere.”
The measurements were performed in a solar park in Akaiwa, Okayama prefecture, Japan, operational since 2021. A total surface area of 494,73.18 m² under the solar panels was covered with grassroom and clover using a syringe-based method. Fertilizers, seeds and fibers were mixed in a solution to prevent erosion. Three measurement methods were used at three locations: loss on inflammation (LOI), Tyurin and the total method for organic carbon (TOC).
Image: Kyushu University, Environmental Challenges, CC by 4.0
While the LOI method estimates organic carbon by burning soil and measuring weight loss, Tyurin uses chemical reactions to oxidize carbon and titration to measure it, and TOC measures directly from burned soil. “We were surprised by the significant variability in SOC measurements between different methods. LOI and the Tyurin method yielded similar results that differed considerably from those obtained through automated dry combustion with the help of TOC meters,” added Professor Yagi.
Based on this, the researchers decided to concentrate on the LOI method and used it to measure 21 further soil sites at the test location. “Although the LOI method turned out to be practical, the use of more precise techniques (for example, automated dry combustion) and with deeper soil layers would strengthen future assessments,” the group emphasized.
According to the results of all measured locations, the SOC had an annual increase of approximately 0.927 TC/HA (3,397 TCO₂e/HA) at the Okayama project, which led to net GHG removals of 85.8 TCO₂e for two years. The team also suggests that well -managed vegetation under the panel could continue to yield annual reductions of approximately 168.1 TCO₂e.
“By integrating the infrastructure of renewable energy with vegetation -based carbon removal, this approach offers a promising path for emission limitation and the generation of carbon credit. It can supplement continuous efforts in forest management, in particular in areas where steep ground or fragmented ownership limited,” concluded. “Continued research and a broader acceptance of standardized measurement methods can help Japan to develop a more robust voluntary carbon market and to promote the total goals for carbon arm restriction under the unique geographical limitations.”
The experiment was described in detail in “Soil Organic Carbon Credits Of Grass Mat And Klaver Plants Under Solar Panels“Published in Environmental challenges.
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