SOILSENSE handheld device for soil monitoring

Soil is a precious, essentially non-renewable, resource presently endangered by human activities. The road to protection goes through knowledge: there is the need to raise the global understanding of the importance of soil. Therefore, diffuse measurement of soil properties is central to soil conservation and management. We present a device tailored to monitor the soil quality by adopting a low-cost open-source multi-sensor approach. The device measures in the field soil temperature, moisture, density and pH. Furthermore, the device has a penetrometer to obtain a depth-resolved soil hardness characterization down to 60cm from the surface. The device is controlled via Bluetooth by a custom-built Android App. The application georeferences each data and uploads the generated-les to a server for data elaboration aimed to build and populate a map with all the collected soil quality measurements. The device is equipped with a temperature/moisture sensor, a 0-5kg load cell used as weight scale for density measurements, a reflectance spectra sensor for automatic reading pH test strips and, on the bottom side, a penetrometric tip mounted on a 100kg load cell coupled with an optical time-of-flight sensor for depth-referenced penetrometer measurements. Preliminary test evidenced good correlation between in-the-field observations and traditional laboratory tests. The device is easily also by unexperienced users, allowing for applications both in agronomic and in environmental fields, ranging from educational purposes and ICT learning of soil sciences to scientific projects related to soil monitoring and awareness raising Citizen Science initiatives.