Conserving soil organic carbon stocks is an objective of the European Commission’s ‘Soil Deal for Europe’, which aims to improve soil health to support the European Green Deal. Soil can act as a carbon sink, but only when it is healthy and adequately moist, meaning that a robust network for monitoring soil moisture is required. A promising candidate for bridging the gap between large-scale monitoring by satellite remote sensing and small-scale monitoring by point-scale sensors is cosmic-ray neutron sensing (CRNS). CRNS is a non-invasive method which measures soil moisture by detecting ground levels of fast neutrons (radiation caused by cosmic rays in the upper atmosphere). Although CRNS is already in use by five major hydrological monitoring networks, a lack of traceable calibration methods, as well as a lack of knowledge about interference from the environment, has hampered efforts to harmonise CRNS with established moisture monitoring techniques.

This project will develop traceable measurement methods for all monitoring scales. It will establish traceability for point-scale and satellite sensors in order to develop a multi-scale system, as well as to validate CRNS measurements. It will improve the traceability of current CRNS devices and develop procedures to overcome environmental interference. It will also produce good practice guides for calibrating devices and harmonising measurement methods. These methodologies will inform the creation of future monitoring networks, accelerating the uptake of CRNS. The data these networks produce will go on to support climate change monitoring and resource management, contributing towards the goals of the Green Deal.