Printed PHBV ‐Based Sensors as a Real‐Time Proxy for Soil Microbial Decomposer Activity During Drought and Flood Recovery

Fry, Ellen L. and Sharpe, Taylor J. and Atreya, Madhur and Whiting, Gregory L. and Quinton, John N. (2026) Printed PHBV ‐Based Sensors as a Real‐Time Proxy for Soil Microbial Decomposer Activity During Drought and Flood Recovery. European Journal of Soil Science, 77 (3): e70358. ISSN 1351-0754

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Abstract

Improving accuracy of soil decomposition measurements for assessing carbon storage requires high spatial and temporal resolution. To advance the field, continuous, in situ, non‐destructive methods of assessing microbial activity are essential. Here we demonstrate a method to track soil biological activity in real time, by monitoring the change in resistance of sensors based on a biodegradable composite material as it is decomposed by soil microbial activity. These sensors are fabricated using printing techniques and provide a straightforward resistive readout, enabling their interrogation with simple low‐cost electronic systems, thereby providing a path to wide‐scale deployment to provide spatial and temporal characterization of soil biological activity. Using these sensors, microbially derived decomposition of the sensors was monitored in mesocosms comparing species rich grassland soil and a monoculture wheat soil, subjected to either a drought or flooding treatment with a subsequent recovery period. The sensors tracked their decomposition every 30 min for 7 weeks, with decomposition activity subdued by the drought and demonstrate recovery following its cessation. Flooding produced a similar response in the species rich grassland, albeit the recovery was slower. However, in wheat soil, flooding did not reduce decomposition of the sensor which we attribute to wheat maintaining an oxygenated rhizosphere. The developed sensors can shed light on the dynamic nature of soil microbial processes that would otherwise go unobserved.