Soil & Compost:

Compost Contamination


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Jane Sherrott16-May-11 09:43 AM EST 7a   


Subject: Compost Contamination
From: Jane Sherrott
Zone: 7a
Date: 16-May-11 09:43 AM EST

There has been a significant problem with aminopyralid herbicide contamination of commercial composts in the UK and Western Washington. Contaminated composted manures put on vegetable beds suffered serious losses of susceptible vegetables. BC Organic Grower, Volume 14, number 2, Spring 2011 has an excellent article on the few cases seen in the BC Interior. The upcoming June BC Master Gardeners newsletter will have an article on it as well. Googling the topic will bring up dozens of articles. Aminopyralid is registered herbicide for use in Canada by commercial operators but not for gardeners. Contamination of composts is occurring a few times each year in the BC Interior where aminopyralid is used to spray invasive weeds but there are not any reported cases elsewhere in BC. Aminopyralid is an unusual herbicide- animals grazing in fields or eating sprayed hay, silage, etc will ingest it, but it is not broken down by digestion so it will be excreted in manure and urine. Unlike almost all herbicides and pesticides, aminopyralid is not broken down in composting, so allotment gardens in the UK that ordered large loads of commercially composted manure, home gardeners and even commercial organic farmers who used contaminated manure lost vegetable crops. RHS info lines rang off the hook, and the UK temporarily suspended sale of it. Its sale has been reinstated with usage warnings to farmers to ensure manure from animals eating sprayed materials does not enter commercial compost operations. There do not appear to be more than a few infrequent problems in Canada- most commercial composters are very committed to producing an environmentally beneficial product (and grow plants in the products to make sure they are top quality), but has anyone heard of problems due to contamination of composts? Thanks very much, Jane (Please feel free to email me if you would like links to some good articles jsherrott@shaw.ca)


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