“…The study of the impact on PSD is usually neglected in soil amendment experiments because it is difficult to quantify by classical field/laboratory methods, including direct or indirect measurement of PSD from water retention curve (WRC) measurements based on soil water content or geophysical measurements and hydrological inversion (as done by Jadoon et al, 2012; Busch et al, 2013; and Jonard et al, 2015) or WRC measured by pressure plate extractors (e.g., Bittelli and Flury, 2009); multistep outflow (e.g., Bayer et al, 2005; Hollenbeck and Jensen, 1998; Neyshabouri et al, 2013; Weihermüller et al, 2009); or the evaporation (e.g., Schindler et al, 2010; Žydelis et al, 2018), mercury intrusion (e.g., Webb, 2001), and nitrogen sorption (e.g., Kowalczyk et al, 2003) methods. As an alternative, noninvasive measurement techniques can be used, such as MicroCT (e.g., Koestel, 2018; Pohlmeier et al, 2018; Smet et al, 2017), synchrotron radiation and/or microtomography (e.g., Peth et al, 2008), or nuclear magnetic resonance relaxometry (NMRR) (e.g., Jaeger et al, 2009; Stingaciu et al, 2010).…”