Hot movements on soil surfaces – Innovative insights into microbial dynamics using passive infrared thermography

• Published in: Geoderma 2021-03, Vol.385, p.114879, Article 114879
• Main Authors: Schwarz, Katharina, Heil, Jannis, Marschner, Bernd, Stumpe, Britta
• Format: Article
• Language: English
• Subjects: Hot movements; Methodical development; Microbial activity dynamics; Microscale; Passive infrared thermography; Spatio-temporal approach
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2020.114879

[Display omitted] •Microbial activity can be detected and quantified with IR thermography.•The thermal response correlates with the applied glucose rates.•Optimized environmental conditions reduce IRT detection limit of microbial activity.•Soil temperature increase of up to 1 K is associated with microbial activity.•IRT identifies of so-called hot movements in a high time-spatial resolution. Passive infrared thermography (IRT) has great potential for detecting and imaging microbial hot spots and hot moments on soil surfaces. A combined evaluation of such phenomena is considered in this study in so-called “hot movements”. This study identifies optimal soil incubation conditions and data preprocessing for the reliable identification of microbial activity on soil surfaces at high temporal and spatial resolution using IRT and substrate-induced respiration techniques. Two soil samples varying in microbiological properties were used for all experimental setups. Incubation conditions for thermal imaging were optimized with a focus on the application of varying glucose concentrations, glucose application techniques, relative air humidity, and ambient air temperature. Experimental data was optimized mathematically using a sequence of preprocessing methods. For data validation, the microbial activity of the soil surfaces determined by surface temperature was related to soil respiration, monitored by conventional CO2 determination. Generally, the application of glucose resulted in a temperature increase on the soil surfaces. A linear relationship (R2 = 0.84, *P  95% since less relative humidity levels resulted in intensive evaporation so that the associated cooling effect controlled the thermal dynamics on the surfaces. Ambient air temperature fluctuations influence soil surface temperatures, but these c