Fig 1.
Hierarchical data structure defining the study design.
Dashed arrows represent duplicates of the same sampling structure shown. Levels in italic text are not independent replicates. Sieve plummet balance method, SPM; Laser diffraction method, LDM.
Table 1.
Chemical properties for each soil sample and the sieve plummet balance method (SPM).
Table 2.
Cumulative particle size distribution parameters for high and low soil concentrations (average of 2 reps).
Fig 2.
Plot of laser diffraction method cumulative particle size curves with the calculated K statistic.
Plots are labelled with the sample ID (see Table 1), 1–5, Podosol; 6–11, Dermosol; 12–16, Chromosol; 17–22, Vertosol. Columns are alternating Topsoil/Subsoil. No pretreatment (NP) solid blue line; with pretreatment (P) dashed red line.
Table 3.
Linear mixed model based estimates of mean Ki for the four soil types, two depths, and their interactions.
Table 4.
Correlation of soil features with K (n = 22).
Fig 3.
Plots of Lin’s concordance correlation coefficient (CCC) for different laser diffraction (LDM) equivalent sieve sizes.
Peak in Lin’s CCC provides the LDM equivalent thresholds that best match the SPM thresholds (shown as a vertical dashed line) of: (a) < 2 μm. (b) < 20 μm. (c) < 200 μm. NP, solid blue line; P, dashed red line.
Fig 4.
Scatter plot of cumulative particle size (%) using sieve plummet balance (SPM) and laser diffraction (LDM).
Results for LDM are NP. Blue circles correspond to coordinates for LDM < 9μm (x-axis), SPM < 2μm (y-axis); red triangles for LDM < 30μm, SPM < 20μm; and green crosses for LDM < 280μm, SPM<200μm.
Table 5.
Mean and standard deviation (SD) of the empirical distribution of laser diffraction measurements (% less than or equal to thresholds) at 9, 26 and 275 um for non-pretreated (NP) and pretreated (P) samples (n = 24–48).
Fig 5.
Histogram of particle size distribution.
(a) Podosol topsoil. (b) Vertosol subsoil. P, green bars; NP, red bars.