pH00
| pH at depth 0-10cm |
pH30
| pH at depth 30-40cm |
pH80
| pH at depth 80-90cm |
e00
| electrical conductivity in mS/cm (0-10 cm) |
e30
| electrical conductivity in mS/cm (30-40 cm) |
e80
| electrical conductivity in mS/cm (80-90 cm) |
c00
| chloride content in ppm (0-10 cm) |
c30
| chloride content in ppm (30-40 cm) |
c80
| chloride content in ppm (80-90 cm) |
Laslett, G. M. (1989) Kriging and splines: An empirical comparison of their predictive performance in some applications (with discussion). Journal of the American Statistical Association, 89, 319-409