Comparison of cosmic-ray neutron sensing and gamma-ray spectrometry for non-invasive soil moisture estimation over a large cropped field

Abstract

Soil moisture is a key variable for supporting agriculture and forest management. This variable, however, shows strong variability in space and time and its correct quantification is still difficult in many practical applications. In the present study we compare two innovative non-invasive sensors developed for the estimation of soil moisture over large area. The first one is a new sensor based on cosmic-ray neutron sensing approach. The second one is a new gamma-ray spectrometer specifically designed for this type of application. Data have been collected at a large, cropped field at Ceregnano, Italy in 2021. The results show that both sensors well capture the local hydrological conditions, and they can be considered reliable methods for soil moisture estimations. In both sensors, however, the signal shows to also be sensitive even if to a different degree to water in the biomass, highlighting the need of corrections when fast plant growth is expected.