Please have a look of the attached files.

Thanks J. C. Tarafdar , but none of those studies show ascorbate leves IN SOIL...

You can contact Mr Debabrata Panda ( Central University of Orissa, Centre For Biodiversity And Conservation Of Natural Resources). His study titled " Ascorbate peroxidase and Ascorbate Regeneration System in Rice " could help you, Who knows?

thanks Rachid Aboutayeb , but I need published reports (it's for a regulatory affair...)

You can ask the author on this platform of researchgate. He will be helpful i hope.

Good luck