missing properties and procedures

[bkempen]

While exploring (and using) the content of the GloSIS vocabulary I came across a couple of issues:

PROPERTIES:

• extractable Al is always tied to a specific procedure (oxalate, dithionite, pyrophosphate). There is no entry for Al with an unspecified extraction method (Aluminium (Al) -extractable) like there is for other elements (e.g. http://w3id.org/glosis/model/codelists/physioChemicalPropertyCode-Borext). I have a dataset containing extractable Al (with Mehlich III) for which it is not possible to find a suitable entry in the vocab.
• there is no distinction between the coarse and fine silt fractions (as we have with the sand fractions). Please add coarse silt and fine silt to the vocab.
• the various SandSizeFractions, SiltSizeFractions and ClaySizeFractions are not really usable since fraction size is not specified (e.g. https://vocab.isric.org/glosis_cl/en/page/sandPropertyCode-SSF1). The particle size distribution of each fraction should ideally be defined explicitly (for instance based on two/three most commonly used particle size distributions used in soil science). E.g. SandFraction_0.5-2mm; SandFraction_0.25-0.5mm, SiltFraction_0.002-0.02mm, SiltFraction_0.02-0.05mm, SiltFraction_0.02-0.063mm. This would make these entries much more usable.

PROCEDURES:

• extraction procedures typically used for Al, Fe, Mn are missing int the procedures list: oxalate extraction, dithionite extraction, and pyrophosphate extraction

[pvgenuchten]

Bas, try to create a single issue per item, so we can follow up separately...

related to the sand size fractions, a definition of a fraction can be added at https://github.com/glosis-ld/glosis/blob/dbf6e5b537ec8f63ed50076a33a361bcb38071df/csv_codelists/glosis_cl.csv#L277

[bkempen]

Done in #130, #131, #132, #133