TCEQ - Identity of soil information from a harmonised database

[peterwadeuk]

Greetings good persons.

My current task is to explore the possible transitory storage of atmospheric carbon dioxide in soils by the accelerated weathering of basalt powder amended in the soils.

I have some soils data to model with PHREEQC. The data originates in a harmonised database published by Shangguan (2014) "A global soil data set for earth system modeling". The database contains elements from the WISE database.

I have attached a record from the database representing a soil from the region of Champagne, Illinois.

Within the database is a field denoted "CaCO3 (%-of-weight)".

If I take this to be solid carbonate I can't reproduce the soil water pH values. I project pH values greater than 7.0, whereas the soil water extracts in the database are reported to be 6.5.

In the ISRIC-WISE database this field is identified with fields from other databases denoted "TCEQ - Total carbonate equivalent".

My question is, is TCEQ soluble alkalinity, or is it solid carbonates?

All the best,
Peter

[peterwadeuk]

The reason I thought this number may represent Alkalinity is expressed on this webpage: http://www.owp.csus.edu/glossary/calcium-carbonate-caco3-equivalent.php