From the webpage:
Used for indexing information resources, Agrotagger is a keyword extractor that uses the AGROVOC thesaurus as its set of allowable keywords. It can extract from Microsoft Office documents, PDF files and web pages.
There are currently several available services that can be accessed either as web interfaces for manual document upload or as REST web services that can be programmatically invoked:
Following up on the AGROVOC thesaurus, FAO thesaurus links with reegle, and found this interesting resource.
Doesn’t seem like a big jump to have a set of keyword that create topics, associations and occurrences With document author(s), journal, place of employment, etc.
Would need proofing but on the other hand could produce a topic map for proofing tout de suite. (No Michel, I had to look it up. 😉 )