Units: g cm\(^{-3}\).
The bulk soil density (DENS) was determined using the method of the volumetric ring (\(\sim3\) cm height x \(\sim5\) cm diameter) \citep{ClaessenEtAl1997}. The bulk soil density was not determined in the locations where the soil was very shallow or stony.
Units: mmol kg\(^{-1}\).
The exchangeable calcium (CALC) and magnesium (MAGN) were determined by atomic absorption spectroscopy after extraction with 1.0 mol L\(^{-1}\) KCl solution \citep{ClaessenEtAl1997}. The exchangeable sodium (SODI) and potassium (POTA) were extracted with a 0.05 mol L\(^{-1}\) HCl solution + 0.025 mol L\(^{-1}\) H\(_2\)SO\(_4\) (Mehlich-1 solution). They were quantified by means of flame atomic emission spectrometry \citep{TedescoEtAl1995}.
The exchangeable acidity (EXAC), also know as exchangeable aluminum, was extracted using the same 1.0 mol L\(^{-1}\) KCl solution used to extract the exchangeable calcium and magnesium. It was determined by titrimetry with 0.025 mol L\(^{-1}\) NaOH solution \citep{ClaessenEtAl1997}. The potential acidity (POAC) was determined with 1,0 mol L\(^{-1}\) calcium acetate solution at pH 7.0 and titrated with 0.0606 mol L\(^{-1}\) NaOH solution \citep{ClaessenEtAl1997}.
The sum of exchangeable bases (BASES) is given by the sum of the exchangeable calcium, magnesium, sodium and potassium. The effective cation exchange capacity (ECEC) is the given by the exchangeable acidity plus the sum of exchangeable bases. The potential cation exchange capacity (CEC) is given by the potential acidity plus the sum of exchangeable bases. Note that the standard method for determining exchangeable bases relies on the use of barium chloride [BaCl\(_2\)].
The base saturation (BASA) is given by the sum of exchangeable bases divided by the potential cation exchange capacity. The saturation of the ECEC with exchangeable acidity, or the aluminum saturation (ALSA), is given by the sum of exchangeable bases divided by the effective cation exchange capacity. The results are multiplied by 100. Units: percentage.