where Ec is the element concentration, BD is the average bulk density of
the reference land use (i.e., forest) in each soil landscape and ΔD is the
thickness of the sampling depth. The average bulk density of the reference
land use (i.e., forest) is normally used in order to compare the
same soil mass and avoid the interference of bulk density changes that
often result from land-use changes due to management practices that
compact or loosen the soil (de Blécourt et al., 2013; de Koning et al.,
2003; van Straaten et al., 2015; Veldkamp, 1994).