FluxMate: An off-grid, cost-effective and dual-mode automated chamber system to monitor carbon dioxide fluxes in grassland ecosystems

Measuring greenhouse gas (GHG) fluxes in an ecosystem is essential to assess their contribution to global warming. Automated chamber systems can capture high-frequency data to estimate GHG fluxes. An automated dual-mode stand-alone chamber system was developed to measure carbon dioxide (CO 2 ) fluxes in agricultural ecosystems. The array mode consists of several chambers connected via tubing to a research-grade analyser, whereas the independent chamber mode consists of low-cost sensors inside each chamber. Both modes calculate fluxes, measure environmental conditions, and record images of the vegetation inside the chambers to calculate vegetation indices. The low-cost sensors showed a reliable estimation of CO 2 concentration against a research-grade gas analyser (MAPE < 22.1%, RMSE < 25 ppm, CCC > 0.96) and CO 2 fluxes (CCC = 0.97, R 2 > 0.94, with an average RMSE of 4.04 and MAE of 2.48 kg CO 2 ha hr -1 ). Furthermore, CO 2 fluxes followed diurnal patterns similar to the research-grade analyser, with CO 2 uptake during the daytime and release during nighttime. On average, CO 2 fluxes from the sensors underestimated fluxes by 10.7% compared to the research-grade analyser, with minimal systematic linear deviation from the 1:1 line (C.b > 0.99) and 95% of the error being random. Overall, the independent automated chamber system introduced in this study can measure CO 2 fluxes at a lower cost and with a more flexible approach compared to the research-grade analyser because individual chambers do not need to be connected to an analyser. Independently, low-cost chamber systems could allow scaling up measurements and replications of fluxes in agricultural systems.