Possibly inaccurate soil salinity values

[sarahbayley]

Not exactly a 'bug', but a data issue I hope can be addressed or clarified. I'm noticing that the soil salinity ratings don't match very well with the USDA source and I can't seem to find where else that data is sourced from.

The USDA uses the following criteria for their rating:

What is the plant’s tolerance to soil salinity? Tolerance to a soil salinity level is defined as only a slight reduction (not greater than 10%) in plant growth. None = tolerant to a soil with an electrical conductivity of the soil solution extract of 0-2 dS/m; Low = tolerant to 2.1-4.0 dS/m; Medium = tolerant to 4.1-8.0 dS/m; High = tolerant to greater than 8.0 dS/m.

    None, Low, Medium, High

Trefle, on the other hand, uses a scale of 0 (untolerant) to 10 (hypersaline).

I'm wondering what the criteria is for placement on this 0-10 scale and which source is using this scale. This will help me label/explain these values in my app or report any errors if there are any.

Here's a sampling of plants with salinity ratings above 1 and their corresponding rating on the USDA site:

Trefle ID | Scientific Name | Trefle soil salinity | USDA soil salinity | USDA source link

107095 | Argentina anserina | 2 | low | Link
149757 | Leymus arenarius | 3 | high | Link
189317 | Trifolium fragiferum | 3 | high | Link
175834 | Rosa rugosa | 3 | low | Link
147570 | Lathyrus japonicus | 5 | medium | Link
107435 | Armeria maritima | 6 | low | Link
111034 | Bassia hyssopifolia | 8 | high | Link
177013 | Ruppia maritima | 8 | medium | Link
131629 | Eleocharis parvula | 8 | medium | Link