Development of Low-Cost Soil Flux Chamber for CO₂ Release Measurement

Accurate measurement of soil CO₂ flux is essential for understanding terrestrial carbon dynamics and quantifying greenhouse gas emissions from soil. However, the complexity and high cost of traditional measurement equipment limit its wide adoption in agriculture and other terrestrial ecosystems, including grasslands and managed field environments. In this paper, we developed a low-cost, automated soil CO₂ flux chamber for soil CO₂ flux monitoring. The flux chamber utilizes a commercially available MH-Z19 NDIR CO₂ sensor (Winsen Electronics Technology Co., Ltd., Zhengzhou, China), integrated with a Raspberry Pi microcontroller (Raspberry Pi Ltd., Cambridge, UK; manufactured by Sony UK Technology Centre, Pencoed, Wales, UK) for automated data collection and remote monitoring. The collected data are wirelessly transmitted to a computer or mobile device for real-time display. The total material cost of the system is less than $162. Side-by-side field measurements with a commercial LI-COR 8200-01S chamber (LI-COR Biosciences, Lincoln, NE, USA) showed that CO₂ fluxes measured by the low-cost chamber were consistently lower than those measured by the commercial instrument, averaging approximately 0.75-0.80 times the LI-COR values, indicating systematic underestimation in magnitude, while showing strong linear agreement (R² ≈ 0.98-0.99) across repeated field measurements. This indicates that the system reliably tracks relative changes in soil CO₂ flux, although a systematic bias in magnitude is present. This affordable and user-friendly chamber improves accessibility for researchers and field practitioners, enabling practical monitoring of soil CO₂ flux in applications where cost and portability are critical.