Why would a field be fenced with about half a metre high green plastic sheeting?

[Shoshe]

Just took the dog for a walk in Tidworth in Wiltshire, the field was full of wildflowers, the far end of the field had a cleared part, with what looked like archaeological trenches in it?

I have googled but cant find out what it is, any ideas?

we have that locally and it is for a great crested newt survey