Recently a well-known gardening blog featured a guest posting by a garden writer who made a case for using Canadian sphagnum peat moss as a horticultural amendment. He defended his preference through “facts” provided by the Canadian Sphagnum Peat Moss Association.
This is kind of like relying on the petroleum industry for the most objective information on the environmental effects of oil spills. Or the tobacco growers association for data on the effects of smoking on human health. C’mon now. We know we should consider the source of our information, right?
This isn’t to say that industries don’t have their own scientists conducting research, or that their research is unreliable. But to depend on industry talking points alone ignores the vast body of information provided by independent university researchers.
Several years ago I reviewed the scientific literature on the topic of peat as a sustainable resource; that column can be found here as well as in my most recent book (The Informed Gardener Blooms Again). Rather than repeat what I wrote there, I’ve conducted a quick overview of the research conducted on Canadian peatlands published in the last 10 years.
There are many such articles. And in general the results are not positive. Here are some of the highlights (or lowlights):
- Peat harvesting permanently alters the hydrology of bogs so that natural regeneration is impossible
- Sphagnum does not easily regenerate on degraded peatlands, causing the sites to become drier over time
- Species composition of harvested peatlands is not the same as on undisturbed peatlands
- The mulches used in peatland regeneration decompose and become significant sources of carbon dioxide
- Natural peatlands are long-term sinks of atmospheric CO2, while mined peatlands increase atmospheric CO2 levels
- Amphibian populations, already hampered by acid deposition, are further threatened by peat mining
- Volunteer birch trees on abandoned peat mines accelerate water loss
If we, as gardeners, deliberately choose to use unsustainable natural resources, we need to be fully aware of the consequences. Unquestioned acceptance of industry talking points lends nothing to the discussion.
Thank you.
Peat doesn’t really have any nutritive value anyway, does it? It just adds organic matter and is not as good as compost.
Kenny, it’s mostly used for its water-holding capacity. That’s about it.
Linda, Are you going to weigh in on the whole Bayer/EPA controversy of this week?
Shira, I think that’s Jeff’s post for today.
In the midwest, we frequently hear about using Sphagnum peat moss to amend soils for blueberry and Rhododendron/Azalea beds. The benefits being to use it for its acidifying properties and organic matter benefits. I remember one fruit specialists recommending 1 part soil to 1 part peat moss for blueberry beds….what alternatives could we suggest for these situations? I realize that perhaps we should only choose to plant or grow Azaleas and Rhododendrons when the soil pH is in a suitable range, but what about for blueberries or similar fruit crops?
Also thank you for bringing this matter up…knowing the environmental benefits of bogs, I’ve often wondered why we (the gardening collective we) have recommended peat moss as
19e0
much as we have….It seems for many cases the environmental costs far outweigh the benefits, even as good as they may seem to be.
Thank you for writing about this!
Thank you for this! I read the pro peat use piece you mentioned and wanted more of the science that isn’t peat industry generated. Thanks!
Linda, Have you written about peat alternatives for homemade seed starting mixes? Wondering if you have any recommendations. Also, on my blog, I posted a link to the pro-peat article and your anti-peat article and a very spirited discussion started. Most folks were anti-peat but there was no consensus on alternatives.
Karen and Erik, I’ve intended to write an article on peat alternatives for quite some time. I just need to sit down and do this. I will make that a new year’s resolution, ok?
Refreshing article Linda and good to see some basic scientific common sense being talked about peat. Here in the UK we have major problems in getting the message out to gardeners that using peat is bad news for the world around us. There is much pro-peat propaganda ably distributed by our gardening media, and, perhaps more insidious, much lobbying of politicians by vested business interests. A very unhealthy combo. I wrote the following article on the delusional idea that peat is a ‘green’ and ‘renewable’ resource.
http://www.kitchengarden.co.uk/news/the-peat-delusion
John, it’s great to see the piece in Kitchen Gardens (a site I hadn’t visited before). Thanks for your comment and the link!
Locally produced compost is a pretty darn good substitute for trucked-in peat, whether you’re potting things up or planting blueberries, etc. Tony Avent of Plant Delights Nursery uses 2 parts compost and one part sand for his potting soil and I ‘ve switched to that mix as well. Happily. And as far as needing peat to make the soil acidic enough for blueberries–any pile of organic matter is acidic. How do you think blueberries were planted before we had bags of peat. For peat’s sake.
We have found that coconut coir is an excellent substitute for peat moss. It adds water holding capacity and loft to the soil. It breaks down, but only relatively slowly, and the resulting soil is quite nice. It’s an ideal amendment for heavy clay soils like we have (North California, SF Bay Area).
The coir is imported from halfway around the world (it’s a byproduct of coconut production; our source comes from Sri Lanka) so it’s not exactly green. But it’s shipped in compressed bricks (rehydrate at home) and it’s an agricultural byproduct rather than a mined, virgin material. So its impact is much less than peat moss (which is also shipped, and not as densely as coir).
Frank and Brent, I agree that compost and coir are both good (if not perfect) alternatives to peat. I know there are some other good substitutes. I’ll try to get that review finished soon!
Linda, that was a very good article. I had read Jeff’s article previously and he was touting peat moss as a good amendment to increase drainage in high clay soils.
In this situation compost would appear preferable regardless of the eco issues as peat has no staying power once it’s removed from the anaerobic and acidic conditions of the bog. The closer you can get to humus the more bang for the buck when amending clay.
I run a bearing age fruit tree nursery and do use some peat in my mix for my 15 to 25 gallon pots. I’m afraid coir is not a financially reasonable alternative in the northeast but ground pine bark is supposed to do pretty well so I’ll be looking for that next spring.
Linda.
As always, thank for the wisdom you share.
Regarding peat moss check out this scary post by P Allen Smith: http://www.pallensmith.com/articles/sustainable-peat-moss-harvesting
Even more frightening is the number of responses to his article in support.
Blind leading the blind?
Happy holidays.
Grateful Joe
Joe, thanks for the kind words. I’m not sure I should thank you for the link, which you accurately describe as “frightening,” as are the slavish responses. Blog readers should definitely take a look at what passes for “valuable information.”
Glad to see this level-headed item on Canadian peat. Recently I saw an article written for a syndicated local newspaper extol the virtues of Canadian peat. As if that wasn’t bad enough, he “debunked” the Canadian peat “myth,” urging his readers to believe that there is no reason to be concerned about the mining of this resource.
So are coconut plantations good for the local environment? When land is turned over to coconut farming, are all the local animals happy? Coir isn’t coming from backyard trees – it’s an industrial farming prduct.
Mark, you’re changing the subject. I’m not making any value judgements about production agriculture, whether it’s coconuts or wheat or spinach. Realistically, production agriculture is here to stay. If we can reuse the waste products, that’s certainly better than strip-mining relatively pristine ecosystems like peatlands.