09. Heat and Mass Transfer

Soil organic matter in soil significantly influences fertility by providing nutrients to plants and plays a crucial role in the physical, chemical, and biological properties of soil, which are vital for plant growth. Furthermore, soil organic matter is a critical component in the biogeochemical cycles of carbon and nitrogen. While biomass waste has typically been burned, an alternative method of converting it into biochar and burying it in soil has gained attention as a method for carbon storage in agricultural land. Conventionally, the estimation of soil organic matter content in soil is often performed visually based on soil color, a method that requires considerable expertise and poses challenges in quantitatively and reproducibility. This study explores a novel quantitative approach for measuring soil organic matter content by heating the soil with light, recording the surface temperature changes of the soil using thermography, and analyzing the temporal thermal images to assess the temperature variations corresponding to each pixel. The research identified significant differences in temperature change patterns between soil and soil organic matter containing. Utilizing these differences, we developed a method for distinguishing soil organic matter. Theoretical investigations revealed that these temperature change discrepancies are attributable to the rapid increase in radiative heat transfer within the porous soil organic matter as the temperature rises. Alongside conducting validation tests, we also explored ways to reduce measurement time by improving the analysis algorithm.