Comparing electronic probes for volumetric water content of low-density feathermoss

Purpose - Feathermoss is ubiquitous in the boreal forest and across various land-cover types of the arctic and subarctic. A variety of affordable commercial sensors for soil moisture content measurement have recently become available and are in use in such regions, often in conjunction with fire-susceptibility or ecological studies. Few come supplied with calibrations suitable or suggested for soils high in organics. Aims to test seven of these sensors for use in feathermoss, seeking calibrations between sensor output and volumetric water content. Design/methodology/approach - Measurements from seven sensors installed in live, dead and burned feathermoss samples, drying in a controlled manner, were compared to moisture content measurements. Empirical calibrations of sensor output to water content were determined. Findings - Almost all of the sensors tested were suitable for measuring the moss sample water content, and a unique calibration for each sensor for this material is presented. Differences in sensor design lead to changes in sensitivity as a function of volumetric water content, affecting the spatial averaging over the soil measurement volume. Research limitations/implications - The wide range of electromagnetic sensors available include frequency and time domain designs with variations in wave guide and sensor geometry, the location of sensor electronics and operating frequency. Practical implications - This study provides information for extending the use of electromagnetic sensors to feathermoss. Originality/value - A comparison of volumetric water content sensor mechanics and design is of general interest to researchers measuring soil water content. In particular, researchers working in wetlands, boreal forests and tundra regions will be able to apply these results. ?? Emerald Group Publishing Limited.