Here is a link to it: Detecting persistent herbicides in compost
Unless you are very scientifically-minded, you will probably want to read only the Executive Summary at the beginning and the Conclusions at the end!
The general gist of the article is that the study found that a very high proportion of commercial composts are contaminated with residues from weedkillers, and these residues have a very adverse effect on vegetables and flowers.
Please do whatever you can to raise the profile of this issue, and lobby for the use of clopyralid (and aminopyralid) weedkillers to be discontinued.
Sorry about the long comment :) My comment is based upon the amateur gardener testing for herbicide and ignores a controlled environment. Trying to reproduce scientific tests at home and getting the same results isn't always easy.
ReplyDeleteI think I read in that study that Peppers were less effected than Field Bean, they were suggesting that Field bean was more sensitive to it...that's not what I observe. I think there is a flaw in these type of studies where they don't grow to full maturity. If growing to test the medium I would do pea, which showed first signs followed by runner bean and cape gooseberry and then field bean, although the pot I grew to test for herbicide that showed the best and quickest results was a pot with Field bean, pea and runner bean. Some of my field beans didn't show any signs when they were young (4 or 6 weeks) but then showed up.
Since I grew a lot of different plants in affected compost and manure I could see a lot of difference. All my field beans came through and ended up as being not bad once planted out. Tomatoes ended up being bad but still produced fruit, but not much. Peas were the worst, not a single pod produced. Cape gooseberries performed uniformly the worst with tiny plants and no mature fruit. Peppers turned out to be hit and miss. I grew 7 Sweet banana peppers and 3 plants grew well with distorted leaves, flowered but no fruit, 1 with odd, tiny fruits, and 3 suffered absolutely no signs. All from the same packet all the same compost.
It's also very variable. Some of the cape gooseberries showed signs in the modules, got worse when planted out (the bed also had contaminated compost / manure) but then grew out of the problem when their roots went deeper and grew through the infected compost. These plants have ended up showing no signs when fully mature.
I also think that a lot of variability is down to watering. The more wet / moist the compost the earlier the signs show and it would appear that some plants, from the same seed packet, are effected differently.
If you want to test for contamination I would suggest several different seeds and not rely on just one, such as field bean and keep them very moist. I would also then continue growing on with different composts just in case some plants show signs in later maturity. At least then some will be OK.
I'm not convinced a 4 week test in modules will always show the contamination for home growers.
With this clearly being an issue, I think that some producers would be guaranteeing their compost is clear of contamination if they could be sure with a simple test and since they aren't (as far as I can tell) I would suggest that there isn't a good cheap easy test, either that or that they all know that they are affected to some degree because a chemical test would show this contamination surely.
Thanks for this, Andy, with its thoughtful insights. I too think that the onus should be on compost manufacturers to ensure that the product they are selling is fit for purpose. It's just not reasonable to expect every amateur gardener to test every bag of compost for at least 4 weeks before sowing anything!
DeleteFrom my research on the subject of contaminated compost and manure my conclusion is that any type of testing isn't actually effective. The only thing that testing can prove is that contamination iIS present and not that it isn't. Plants growing without signs of contamination do not approve that the compost is not contaminated.
ReplyDeleteThe hormonal pesticides can be present in compost and manure for ages without showing any effects at all. The residue is released when the plant material breaks down and it's released over a period of time. This means that' the gardener could do a test and assume that the compost was unaffected but it could be that the plant material had not yet broken down enough to release the residue. When we were affected when this problem first occurred even the experts told us that testing was extremely unreliable. Our potatoes grew very well and very healthily for quite awhile before succumbing to the contamination and then the contamination didn't hit every plant at the same time it acted in a sort of a wave fashion.
Also the contamination may not be evenly distributed through the compost, this is especially true when the contamination comes from manure as the compost is more likely have been subjected to some form of mechanical mixing. If the source material is only affected in parts of the batch then the
The ingredients can be sourced from a range of different batches and some batches could be affected and others not. Also you cannot rely upon one particular commercial brand being free of contamination just because you have used it in the past and it has been okay. The use of green waste means that the manufacture of any compost based on this by product is inconsistent as is the se of manure.
As for lobbying I agree as much should be done as possible to publicise the problen but I am not optimistic about the results. Initially we managed to get aminopyralid withdrawn for a period of time but once the manufacturers could offer a plan for stewardship which placed the onus upon the user rather than the manufacturer of the chemicals then the pesticide was allowed to be re-introduced. The problem is that when big business is involved the amateur gardener doesn't really have a strong enough voice. The problem has been around for at least eight years now and no amount of complaining, lobbying or publicising has had the effect of removing the problem. Companies deny there is a problem and continue to perpetuate the problem in doing so. It is also very difficult to actually prove who is responsible for any contamination. I think the only course of action is basically to avoid all compost that have some green waste in the recipe. Maybe if we boycott these compost then the manufacturers of them will start to worry. the problem in doing so. I think the only course of action is basically to avoid whole composts that have some green waste in them.
Of course if we return to peat based compost we will be accused of being environmentally unfriendly. However what is environmentally friendly about using compost that is contaminated with a pesticide that is then released into the soil and perpetuates the contamination for many many years.
Sorry just seen how long this comment has turned out to be.
DeleteNo worries, Sue. I welcome thorough discussion of this under-publicised issue!
DeleteDid you ever write to Monty Don and ask him to feature the problem on GW? Individually, amateur gardens can never make headway against the vested interests of Big Business, but the involvement of a celebrity might just succeed.
DeleteI wrote to everyone that I could think of, Mark. It was pre Monty Don but in fact I did appear on Gardeners World. They came and filmed on the plot for four hours of filming ended in a four minute aired slot. I also appeared on The Politics Show and was on local radio several times. We also had features in nationsl and local papers. We were in close contact with the RHS, the government agencies and DOW. I posted on any garden forum thatI could find and put commemts on many gardening blogs, emailed allotment associations, wrote to garden websites asking them to feature. I even made fliers/posters and sent to garden centres but none of those responded. I even wrote to any celebrity gardener that I could find contact details for, MPs, MEPs, councillors, Prince Charles, trades and environment agencies etc Other people were doing similar things and even then most people remained unaware.
DeleteGosh, I didn't know that you had gone to such lengths! What else can one do to get Big Business to take notice? If only we could get millions of everyday gardeners to boycott the firms that make this stuff...
DeleteI had no idea it was an issue until I had it. I'd never heard about it because I didn't know any other growers before I started reading blogs. Unless you look for the problem or read the correct person's blog you won't stumble upon it...at least I didn't. I have spent a lot of money on compost as a soil conditioner when starting my beds with a local garden centre and a local flower nursery. I also bought trailer loads of organic compost from a local company who make the compost (always including grass) where we know the owner and had many discussions about compost, how it is used etc, how they make it, how they get certified as organic blar blar and at no stage did it crop up. I now question how "organic" organic compost can be if this chemical can slip through. I wonder what they do test for when testing for chemicals when clearly they don't test for the one chemical that is there and will cause a problem when they know the raw ingredients are coming from council grass cutters and green bins. I think the word organic is another sales term with little other meaning.
DeleteAndy: Re "organic" - I agree. It is a much abused and little understood term. Many people are hoodwinked into thinking it means "free from all bad stuff". At least you and I and Sue are doing what we can to publicise the herbicide problem!
DeleteI researched the term organic when applied to gardening products when we had our problems. Apparently compost manufacturers cab put the term organic on the compost and it can mean absolutely nothing as it isn't certified. Apparently gardening products do not fall under the EU. I devoted a page on my website to this subject entitled What is organic? This was accurate at the time of publishing and I am not aware that there has been any changes made.
DeleteIn fact when we were gathering information about victims of contaminated manure one person had actually sourced the manure from an organic farm.
I think the long comments are a good sign of a good post and good subject :) May long comments persist! Some interesting points, Sue, I agree with what you say.
ReplyDeleteI've added an info link on the sidebar of my blog - maybe if other garden blogs did likewise it would help publicise.
ReplyDeleteThanks for doing whatever you can, Sue! We must keep on trying.
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