“…As water has 1.11 times as many electrons per gram compared to most soils, water is 1.11 times as effective in attenuating gamma-radiation compared to typical soils (Grasty, 1997). The expected high sensitivity of gamma spectroscopy to soil water content has triggered numerous studies which addressed a broad range of applications including soil classification (Beamish, 2013(Beamish, , 2014, radon flux mapping (Manohar et al, 2013;Szegvary et al, 2007) and snow water equivalent assessment (Carroll and Carroll, 1989;Peck and Bissell, 1973). Nevertheless, the potentialities of the method for monitoring soil moisture dynamics have been not fully explored yet (Bogena et al, 2015;Pereira, 2011), especially in the field of proximal sensing, which is foreseen to be an efficient strategy for filling the existing gap between punctual measurements, generally provided by in situ electromagnetic sensors (Walker et al, 2004), and remote measurements, typically performed by satellites (Brocca et al, 2017;Zeng et al, 2016).…”