addVolumeFraction() should use smaller vertical grid when horizon thickness is very small

[dylanbeaudette]

library(soilDB)
library(aqp)
library(lattice)

# Bandy Ranch sites data - take HQ pasture site to work in study data
f <- fetchLDM(c('22N0011'), what = "pedlabsampnum")  

plotSPC(f, name.style = 'center-center', color = 'clay_total', id.style = 'side', raggedBottom = FALSE, label = 'corr_taxsubgrp')
addVolumeFraction(f, colname = "total_frag_wt_pct_gt_2_mm_ws", pch = 5)

# replicate the same profile for plotting
d <- duplicate(f, times=5)
# add treatment ID for labels
d$ID <- c('Initial application', 'No trampling, 20 t/ha', 'No trampling, 40 t/ha', 'Trampling, 20 t/ha', 'Trampling, 40 t/ha')

# tinker with margins / y-offset
par(mar = c(0, 2, 0, 3))
plotSPC(d, name.style = 'center-center', id.style = 'side', label = 'ID', max.depth = 25, width = 0.33)

# add column for biochar fraction
horizons(d)$biochar_content <- rep(95, 5) 

# trunc() is vectorized
# best to use integer depths
# now specified as mm
f <- trunc(
  d, 
  z1 = c(0, 3.0, 4.0, 4.5, 7.4), 
  z2 = c(3.0, 4.0, 4.5, 7.4, 9.0)
)

# be sure to set the max depth in mm
par(mar = c(0, 1, 0, 3))
plotSPC(d, name.style = 'center-center', id.style = 'side', label = 'ID', max.depth = 25.0, width = 0.33, cex.names = 1)


addVolumeFraction(f, colname = "total_frag_wt_pct_gt_2_mm_ws", pch = 16, res = 20, cex.min = 0.5, cex.max = 1)