Maximum Depth of Sand

To determine the maximum depth of sand in any given profile requires:
  •  that each horizon in the profile be categorized by using the sand, silt and clay values to place the horizon on the standard texture triangle; and
  •  that the profile be scanned from the surface downwards horizon by horizon for membership in the 'sand' and 'loamy sand' categories. When a horizon is found not to fall into one of these two categories, the upper depth of that horizon was taken as the 'maximum depth of sand' in that profile. If all horizons sampled fell into the two categories, the value '999' was assigned and should be taken to mean that the maximum depth of sand was unknown but exceeded the maximum depth sampled. In all cases, the units associated with depth are centimeters.

The categorization of a horizon required:

  1. The development of an algorithm that can project a point based on the composition percentages into the triangle and, conversely, can convert a point in the triangle into an equivalent point in a Cartesian coordinate system;
  2. The conversion of the vertices of the polygons in the triangle for all soil types into such a coordinate system;
  3.  The mapping of those coordinates into a graphic system such that each soil type was uniquely colored; and
  4. The projection of a given horizon into that graphic system using the composition percentages to determine the color of the pixel at that location which, in turn, indicates the soil type.
If you wish to see the details of the process, click here.