Parametric design for soil gas flux system: a low-cost solution for continuous monitoring

Monitoring soil gas fluxes is essential for understanding greenhouse gas dynamics within the critical zone. One commonly used method involves chamber-based methods which enables the quantification of soil gas fluxes on a specific point at the soil-atmosphere interface. However, point measurements often limit the representativeness of the field-scale processes due to the large spatio-temporal variability of climatic, hydrological, pedological, or ecological factors controlling its dynamics. Additionally, commercial chambers often prohibit deployment over sufficient representative area due to expensive operational and purchase costs. Although low-cost and open-source designs have recently emerged in the literature, solutions enabling adaptability to field-site characteristics and design validation are still lacking. To address these challenges, we propose here a low-cost, parametric soil gas flux system that can be adapted to logistical and field constraints while allowing high-frequency measurement resolution. Along with open-design hardware, we developed software to automate data collection and processing. Laboratory tests, including static and transient experiments, assessed both the sensor and chamber design integration. Our results show strong agreement between the low-cost and commercial gas analyzers in static conditions with CO2 levels up to 500 ppm above background. During transient tests, we successfully replicated CO2 concentration increases using both systems, with comparable response time between eeflux and measurement from the sensors. Thus, we were able to address the data reliability from the low-cost setup, despite different parameters. Ultimately, our approach demonstrates that low-cost solutions can democratize these systems through a flexible framework suitable for various study sites.