A novel robotic chamber system allowing to accurately and precisely determining spatio-temporal CO2 flux dynamics of heterogeneous croplands

• Published in: Agricultural and forest meteorology Vol. 296; p. 108206
• Main Authors: Vaidya, Shrijana, Schmidt, Marten, Rakowski, Peter, Bonk, Norbert, Verch, Gernot, Augustin, Jürgen, Sommer, Michael, Hoffmann, Mathias
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-01-2021
• Subjects: Automatic chamber; Ecosystem respiration (Reco); Gross primary productivity (GPP); Net ecosystem exchange (NEE); Soil erosion; Soil heterogeneity; Net ecosystem exchange (NEE); Automatic chamber; Soil erosion; Soil heterogeneity; Ecosystem respiration (Reco); Gross primary productivity (GPP)
• ISSN: 0168-1923; 1873-2240
• DOI: 10.1016/j.agrformet.2020.108206

•Novel robotic chamber for high small-scale spatial resolution of GHG emissions•Reliability of robotic chamber is shown for CO2 emissions based on sample dataset•Temporal dynamics of CO2 emissions were influenced by phenology/weather and management•Spatial pattern of CO2 emissions were influenced mainly by soil types
The precise and accurate assessment of carbon dioxide (CO2) exchange is crucial to identify terrestrial carbon (C) sources and sinks and for evaluating their role within the global C budget. The substantial uncertainty in disentangling the management and soil impact on measured CO2 fluxes are largely ignored especially in cropland. The reasons for this lies in the limitation of the widely used eddy covariance as well as manual and automatic chamber systems, which either account for short-term temporal variability or small-scale spatial heterogeneity, but barely both. To address this issue, we developed a novel robotic chamber system allowing for dozens of spatial measurement repetitions, thus enabling CO2 exchange measurements in a sufficient temporal and high small-scale spatial resolution. The system was tested from 08th July to 09th September 2019 at a heterogeneous field (100 m × 16 m), located within the hummocky ground moraine landscape of northeastern Germany (CarboZALF-D). The field is foreseen for a longer-term block trial manipulation experiment extending over three erosion induced soil types and was covered with spring barley. Measured fluxes of nighttime ecosystem respiration (Reco) and daytime net ecosystem exchange (NEE) showed distinct temporal patterns influenced by crop phenology, weather conditions and management practices. Similarly, we found clear small-scale spatial differences in cumulated (gap-filled) Reco, gross primary productivity (GPP) and NEE fluxes affected by the three distinct soil types. Additionally, spatial patterns induced by former management practices and characterized by differences in soil pH and nutrition status (P and K) were also revealed between plots within each of the three soil types, which allowed compensating for prior to the foreseen block trial manipulation experiment. The results underline the great potential of the novel robotic chamber system, which not only detects short-term temporal CO2 flux dynamics but also reflects the impact of small-scale spatial heterogeneity.
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