I’m ninety percent sure, that Misarti must be nonsense. Looking at their graphs they measure trace elements in soil at concentrations up to 10^9 ppb, i.e. purity. From the text it is not clear what they measure but the numbers only add up when they set the sum of all soluble metals to 100 %. If so this means that soils with abundant e.g. P will yield low numbers when other elements are even more abundant and those with the merest traces high ones, when other elements have even lower yields.
Harbring is commented on on the Cologne University website.
Here’s the link to this week’s complete list.