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Table 1 Metadata collected at each site. While a range of soil variables were collected, only the subset of variables for which there are clear soil quality guidelines [32] available were used for the random forest models.

From: Using soil bacterial communities to predict physico-chemical variables and soil quality

  Chemical Physical
Measured and used in models pH, carbon (%), total nitrogen (%), anaerobically mineralizable nitrogen (AMN, mg/kg), Olsen P (mg/kg). Macroporosity (MP, % v/v), bulk density (BD, t/m3).
Measured but not used in models C:N, NO3-M (mg/kg), NH4-N (mg/kg), Arsenic* (mg/kg), Cadmium* (mg/kg), Chromium* (mg/kg), Copper* (mg/kg), Nickel* (mg/kg), Lead* (mg/kg), Zinc* (mg/kg).  
  1. *There are clear guidelines around the concentration of metals deemed acceptable, but an insufficient number of sites (< 5%) in the dataset had ‘contaminated’ soils; therefore, these variables were not modelled.