Sulphamate off eBay .
it is a compost activator , it just happens if you water it on green matter it kills it *& turns it into compost material. So make sure that the stuff you want " composting " is not in an area of crop and that it will not leach into veg beds etc or streams
I "composted in situation ", about 10 sq mtr of horsetail during a dry period , after five weeks it was dead , that's over 14 months ago with no regrowth.
Another area I " composted " at the same time now has broad beans growing in it .
Apparently after a four or months of being sprayed on it it turns into plant friendly nitrogen .
It is not licenced as a weed brush or stump killer, its only available as " compost activator " .
Happy composting