I’ve been using the Algorithms for Quantitative Pedology, a very useful set of R packages (aqp, soilDB, and sharpshootR) for working with quantitative soils-related data and especially for plotting those data in interesting ways. I highly recommend trying these out. The plot below represents colors (largely related to organic matter content) and pH in 20 soil profiles sampled across the forest-prairie transition in northern MN (I cheated a little by redoing the titles in Illustrator because I couldn’t figure out how to get them just right in R, a common problem for me anyway).