A Novel Biodegradable Decomposition Sensor demonstrates the dynamic recovery of soil biological activity following climatic stress

 Monitoring of the microbiological processes in the soil is important to understand and the impacts of agricultural practices on soil health. Evaluation of microbially-mediated soil processes usually involves manual sampling followed by laboratory analysis, which is costly, time consuming, physically intensive, non-continuous, and offers limited capacity for measuring changes at a high temporal and spatial resolution. Low-cost soil sensors manufactured using printing techniques offer a potential scalable solution to these issues, allowing for high-frequency in-situ measurement of decomposition rates. Here, we tested the use of novel decomposition sensors to complement or replace conventional laboratory measurements for the evaluation of soil health.

We installed decomposition sensors in undisturbed cores from two similar soils from Cumbria UK, but with high and low nutrient status and contrasting vegetation: a winter wheat crop and a biodiverse meadow sward.  We imposed a climatic stress on the cores as either a flood and drought treatment.  For the flood treatment, cores were placed in a tank with rainwater collected from the site, maintained level with the top of the soil throughout the study. For the control, watering with rainwater was administered three times a week, as needed. The drought was left to dry down through the treatment phase. When the treatments were alleviated, the flooded cores were allowed to drain, and the drought treatment received one litre of fresh rainwater per core.

The decomposition sensors were able to track the recovery of biological activity through time following the alleviation of climatic stress. Drought treatments recovered rapidly, whereas recovery from flooding was less rapid in the biodiverse treatment. The flooded winter wheat treatment was less affected by flooding than the other treatments which we attribute to the plants being better adapted to waterlogging. 

Our findings demonstrate the potential for the proxy measurement of soil processes in-situ using novel printed decomposition sensors, thereby supporting their potential for low-cost, high-resolution temporal and spatial monitoring of soil biological parameters and providing new insights into soil health.