Fig. 5 Mean ± standard error of mean (SEM) soil solution electrical conductivities (dS m^-1) measured using replicate soil cores (circles, ), horizontal TDR probes (lines, ), and solution samplers (squares, ) at 0.15-m depth in Plots I, II, and III. Time domain reflectometry (TDR) estimates are based on in situ mass balance RRP model optimizations vs. applied KNO₃ (Eq. [9]) using vertical surface probes, and applied to horizontal probes at 0.15 m depth