UC Davis

Monitoring CO2 or O2 concentrations within a closed, volume-defined chamber is widely used to quantify soil respiration during laboratory soil incubation experiments. The standard method of using periodic manual gas sampling is costly, labor-intensive, and frequently fails to capture the aerobic respiration process. Thus, tools that allow continuous, real-time tracking of CO2 and O2 concentration changes are needed for soil respiration research. This study presents a new, portable, low-cost (∼$700), open-source sensor system to measure CO2 and O2 concentrations in four closed chambers. We provided non-engineering end-users with step-by-step instructions on how to build the system, enabling replication and customization. System performance was tested by comparing two respiration rates using the same soil—soil with and without glucose added for 1 week. Consistent CO2 production and O2 consumption rates were measured at 1-min intervals, and the reliability of the system was validated by a trace gas analyzer. Two distinctive continuous apparent respiratory quotient time series between two soil treatments were observed, with higher values of CO2 in glucose soil, demonstrating the ability of the system to capture ongoing respiration processes and sufficient sensitivity to distinguish differences among respiration substrates (i.e., glucose). The tested performance of the system highlights its capabilities for soil respiration research and the potential for further adoption in real-time gas monitoring applications.