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Peat Moss and Acidity

Posted by andy10917 NY 6a (My Page) on
Sun, Sep 2, 12 at 10:16

There have been several postings about Peat Moss being "very acidic", and much of the information being posted is by people regurgitating bad information on the Internet - it is clear they are doing that because they often use the same wording.

Peat Moss is somewhat acidic if you test it right out of the bag, but the acidity comes from tannic and humic acids, which are weak acids that easily bind with other items in the soil. While all organic material will go through an acidic phase while decomposing, it does not mean that they are long-term contributors to overall soil acidity.

Look at two groups of people that attempt to use peat moss for generating acidity and you'll see it doesn't work. Blueberry growers find that they must resort to Sulfur to generate a measurable drop in pH, and large-scale aquarium owners that want to imitate the conditions of tropical rivers (I'm one of them) find it doesn't work to generate acidity.

Just like the "pine needles are acidic" old-wives-tale, this is an "everyone knows" item that doesn't hold up in the real world and real testing. The folks that google stuff instead of writing about real testing that they have done do a disservice to others by repeating incorrect information. Often they are repeating the "professional writers" that write about soil one day, and restaurants the next day - with predictable results.

Bottom line, peat moss will not create measurable acidity when used in typical/reasonable quantities in the real world.


Follow-Up Postings:

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RE: Peat Moss and Acidity

Andy, I think a point though is being missed. OK, so peat moss isn't so acidic....no, it aint so....but it is slightly acidic and since most plants...let's say 80% of plants, prefer a slight acidic nature to the soil they're living in, peat moss is a valuable amendment when yu consider its other benefits, such as improving the structure of the soil, its effectiveness to hold water and its wide availability.

What we should forget is the wives' tale of its non-renewability. Scientists have found ways to re-grow peat....OK, so it takes time, lots of time, but the time is on our side. Canada produces sufficient peat moss to treat what is grown on this planet 5 times over and still have reserves. So, whenever we do get to Mars, Canada has enough to start that planet off to producing for its next thousand years.


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RE: Peat Moss and Acidity

As the most recent poster to address this issue I'm not quite sure if I'm offended or not.
First, unlike you, most are not born with inate knowledge. Much of my knowledge comes from researching as reputable of resources as I can access as determined by applying techniques of critical reading (best course I ever took). Most of my sources are university turf programs and I only rely on them when there is consensus.I find this much more time effective than re-inventing the wheel.
Secondly, you are entitled to frame your argument as you please, but not by putting words in my mouth. I have never advised applying peat moss or peat for soil ph adjustment. I use both regularly, confident that there will be no adverse ph change to my soil. I try to give what factual information I possess from research and personal experience and let people draw their on conclusions. In the instant case, I don't know whether the person is buying their peat or peat moss from Lambert or from some entrepreneur that just trucked in a load fresh from the bog. So here is what I know, it's their call. What has your personal testing revealed about the affect of stewing turf over the winter in bog fresh peat?


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RE: Peat Moss and Acidity

Andy explained his source of knowledge, and it was not innate. I think his point is that the pH of peat moss should not be an excuse to use or not use it. Personally I believe it to be a harmless/worthless product good only for trying to bulk up the insides of a temporary hanging basket. I'm not that big a fan of fresh compost, so when you sink compost in ice water for 1,000 years, I'm really not a fan. What is left is the plant parts that will not decompose. It is devoid of nutrients. In my experience it does not change soil structure because it is applied to the surface. And is most often hydrophobic which means it does not hold water. I just cannot conceive of an issue where peat moss is the solution. I do; however, believe it to be a sustainable product, especially if more people come to believe that it is worthless ;-)


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RE: Peat Moss and Acidity

grass1950, I just found another ref on peat moss. Andy was not referring to you.


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RE: Peat Moss and Acidity

dchall_san_antonia,
My original response was much much lengthier and addressed the innate comment, but I thought better of it and it appears I over edited. I wont explain further as that would just resurect what I edited.
andy is a wealth of information. Even so, I always verify whatever he says with other sources. Never found his facts to be in error, but I often disagree with is opinions, conclusions and recommendations.

On another note, I do respectfully disagree with you.

Regarding peat: You mention in the other thread you reference: that the bacteria died centuries ago and that peat wont decompose any further. Although I have found that it is slower to decompse than compost, it does decompose once oxygen and micro-orgs are available again (probably just regurgitation on my part).


Regarding peat moss: This is my amendment of choice. It is slower to decompose than peat or compost and has a cation capacity twice what clay tests at. (regurgitating internet research--no personal testing on my part). Agree peat moss is hydrophobic (personal knowledge), but once wetted, it does hold a lot of moisture for longer times than my silty sand soil (personal observation) and it has been reported that it holds 20 times its weight in water (crap, that must have came from the internet as I certainly didn't do testing). I plug aerate once a year, topdress and drag peat moss into the holes. Results haven't been, "hmmm. that kinda looks like maybe that helped a little, kinda, maybe." Results have been "Holy xow!!!They tore down the stick house and put up a brick home." (that's personal experience--not saying others will duplicate, but I'll keep doing it until I see no benefit.)

So, other than complete responses to threads I've already stuck my nose into, I'll refrain here from "regurgitating" what I thought I knew and leave it to the infallable.


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RE: Peat Moss and Acidity

Is Peat moss as acidic as say Pepsi? No. Will it burn a hole in your yard? No. Is it more acidic than just about any organic amendment anyone would seriously consider adding to their yard? I don't know, but it's up near the top. Calling something very acidic is relative to the application.

I've never heard anyone recommend adding peat moss to permanently alter their soli ph. Obviously adding a sulfur compound would work much better.

Peat moss is excellent for potting mixes. Not because of it's CAC, but because it's sterile. Bacteria has trouble growing in it. Nurseries love to deliver plants in peat moss because the plants have a higher chance of survival for a month or so. If you buy a planter with peat moss, you had better not let it dry out as it will form a brick that will need to be bucket soaked.

In pretty much any lawn application, you're better off adding compost made from grass clippings and/or leaves than peat moss.


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