I researched this topic some time ago, and published these papers ... I hope they will be useful. 

Article The contribution of landmines to land degradation

Thesis LANDMINES AND LAND DEGRADATION: A Regional Political Ecology...

Article Politicizing Indiscriminate Terror: Imagining an Inclusive F...

Dear Nenad,

I suggest to have a look at some papers of prof. Randall Schaetz on bombturbations.

Have a good day.

Lukasz

This report on unexploded ordnance in Cambodia might be a start:

http://www.jmu.edu/cisr/research/aging/aging%202/pdfs/I.pdf

I researched this topic some time ago, and published these papers ... I hope they will be useful. 

Article The contribution of landmines to land degradation

Thesis LANDMINES AND LAND DEGRADATION: A Regional Political Ecology...

Article Politicizing Indiscriminate Terror: Imagining an Inclusive F...

Check this report from Sandi National Lab: http://prod.sandia.gov/techlib/access-control.cgi/1997/971426.pdf

I also found something:

http://www.jmu.edu/cisr/research/aging/aging%202/aging2_2.htm

http://www.mtnforum.org/content/impact-war-and-landmines-environment

http://www.sciencedirect.com/science/article/pii/S0039914000005476

Dear Nenad,

Just an idea for an even longer term of ~100 years: there is a memorial park of (WW I) the Battle of Vimy (France) that is called Canadian National Vimy Memorial (there is a Wikipedia page of that). Here some mine fields were intentionally kept (well sheep are grazing on that). There might be some studies on the environmental status of that site. (Maybe in French.) It would be really interesting. 

As I said, just an idea. Kind regards, Balázs

Thank you Balázs!

In addition to the previous colleagues reading suggestions, I would also suggest reading on the topics of "Acid Mine Drainage"  resulted from buried "gob piles of previous coal mines"

An example of these articles is  that by "Ebraheem et al., 1990".