The fate of persistent herbicides in compost and AD

The Waste and Resources Action Programme (WRAP) has now released reports regarding the fate of persistent herbicides both in compost and AD.

The first report Herbicides in compost can be found at http://www.wrap.org.uk/node/61843  In summary, this report which was carried out with Stockbridge Technology Centre,found that herbicide contamination in composts did not cause problems in the majority of applications and certainly not when used in agriculture. Although it is quite common to find herbicide residues in composts, using the field bean plant response test provides a robust mechanism for preventing them from becoming a problem even in the most sensitive scenarios.  WRAP recommends that compost destined for use in growing media is tested using the field bean test.

Herbicides in AD which can be found at http://www.wrap.org.uk/content/detecting-persistent-herbicides-ad-0  is more of an academic report and the report shows that the analytical techniques used to identify herbicides in complex organic materials like digestates, require considerable development before they can be considered reliable. The value of the report will be for researchers who are interested in developing these techniques.

Previous risk assessment work suggests that the risk of herbicide residues in crops and manures being transferred via AD to sensitive crops is none-to-low.  Nonetheless, we would like to highlight the importance of agricultural herbicide users following product instructions for disposing of treated plant residues and manures.