What are you using to measure the pH of that peat moss?

How are you measuring that pH?

The pH of peat moss varies depending on who is telling you, anywhere from 3.7 to 5.0.

kimmq is kimmsr

Not only do we need to know what type of meter and how you are calibrating it, but also how you are doing the test - how much water vs. how much peat moss, and what you are using for water. These can all affect the results.

Hi kimmq and toxcrusadr. I am using an analogue ph meter to measure. It is something like this:

http://www.amazon.com/MoonCity-Moisture-acidity-Gardener-outdoors/dp/B017GQ9VVY/ref=sr_1_19?ie=UTF8&qid=1463451491&sr=8-19&keywords=ph+meter

I have used it on my garden soil. Managed to get a PH of 5.5 and amended with garden lime to raise the PH. After several hours, I can actually see the PH go up to 6.5, so I suppose the meter was working okay. I have also used the meter with cococoir and coir seems to respond to a slight addition of dolomite as the PH rises. Problem comes when using it to measure peat moss PH.

I used roughly 35 liters of de-compressed peat moss (the insides were really dry). I added about 5 liters of water. I stopped adding when i started to see the peat moss float and repel the water. From what I read, they use dish soap or soaped water as a wetting agent. I topped on another 2 liters of water with some soap and went on the squeeze the peat moss inside the water, hoping they would absorb the moisture. Eventually they looked pretty moist and dark. Then I stick the PH meter in and got a reading of 7.

Could it be that the peat moss I got was extremely dry that it lost its acidic characteristics? Or could it be that it hasn't got enough water? I wanted to use peat moss because the acidic nature should allow me to pack it with plenty of calcium.

Are you using fresh, previously unopened, distilled water? If you are using tap water the pH readings will reflect what ever that is.

My experience with using the pH meters sold in garden centers is that they are not very reliable. I have tested some with vinegar and a baking soda solution and found they gave me the same reading while the same material tested with an expensive laboratory pH meter gave me a pH for vinegar of 3. something (it has been awhile so I don't recall just what) while that of the baking soda solution was about 9. something.

kimmq is kimmsr

Use distilled water, 50/50 with the solids, shake in a jar and then let stand.

I don't know how much soap you used but it's very possible that it affected the pH. I would expect soap to be alkaline if anything, so it could be the cause of the pH being neutral instead of acidic. You might try samples with and without the soap, and a control sample with just soap and water.

Another thing you can do that's low tech to check your meter is to measure your tap water and check your water utility online or call them to get the pH they are delivering. If you don't have a softener. Also check 1 tbsp. of vinegar in a cup of distilled water, and a tsp of baking soda in a cup of distilled water. Those should be about 4 and 8.

Thanks guys! Will try it as once. Right now, I am suspecting that peat did not absorb the water thoroughly. So i did this other experiment in a small bucket of peat. Adding lightly soaped water this time, squeezed the peat in water like crazy and measured. Now I do get a PH oh 5.5. So my guess is that my earlier big batch of peat moss looks wet on the outside, but really is dry on the inside.

I am going to try the experiment with vinegar and baking soda which should prove interesting.

The soap, an alkaline substance, will adversely affect the pH reading you might see.

kimmq is kimmsr

Soap may or may not be alkaline - for example if nonionic surfactants were used, or if the soap was 'pH balanced'. Probably it's alkaline, which is why I suggested a test of just the soap and distilled water.

Anyway you're getting something more like what peat should look like so I think you're on the right track.

I suspect the store bought moss is not at the pH levels of its natural self. Today i added some tap water to the Miracle-Gro Sphagnum moss. I know that my tap water average pH is about 7.9 (the reports are routinely published by my water supply company). Google search says peat moss average pH is around 3.5 to 4.5 range. The sample of Sphagnum mass from bag sat in that water for 3.5 hours because initial test by my pH meter showed 7.0; After sitting for 3.5 hours, the pH meter shows about 6.8 - 6.9 area (its analog meter, so i can not be precise). Even though tap water is alkaline, higher acidity value of moss should have brought the needle well below the reading i was seeing.

The only explanation in my web search is some article that i came across that says the pH meter will need "dissolved salts" in the media, in order to give accurate pH readings. In case Sphagnum moss does not have any dissolved salt, this inaccurate reading may result. What else could be the cause ? Some others have also reported on the web that store bought moss is made to be near pH 7.0 - i don't know if this is reliable article.

BTW, the pH meter (from Amazon) shows pH around 7.7 for the Miracle-Gro Garden mulch even though in the Q/A section the manufacturer says that " most mulches have a pH of between 3.5 to 4.5." So, i am now thinking of verifying the meter with a good quality pH test strip. The reagent based solutions are expensive for me, since i tend to do a lot of pH tests for various purposes.

Unless treated somehow to neutralize the acidity or raise the pH, peat moss will have a low pH......3.5 to 4.5 is typical. And if it had been treated, it would have stated so on the bag. Same with most hardwood barks (eg. mulches)....they will also be well into the acidic side of the scale.

Just mixing these products with water is not going to give you an accurate pH reading. It takes some time for the tannins and humic acid to leach out of the product to get a more or less accurate reading. And by time, I mean more than a few hours....more like weeks or months. btw, soil pH meters are much like moisture meters....unless they are of laboratory grade and have been accurately calibrated to begin with, you will get far more accurate measurements using other methods

I really fail to see the need to measure the pH of peat at all. It is rarely used on its own and if it was, it is safe to assume that it is quite acidic and to adjust with that in mind. Same if used in a potting soil mix. Commercial peat based potting soils are already amended to provide a close to neutral pH and custom mixes are amended with lime to provide the same neutralization. If used to amend garden soil, it will take some time for the effects to be evident and it makes a heck of a lot more sense to test the amended soil, not the peat itself!!

Thanks gardengal. I didn't know that it would take weeks for the peat moss to have an effect on the pH of my tap water (7.9) that was added to it. I will check the bags as you suggested. The intention of the measure was to find out if i need to add garden lime to my mix (which consists of the mulch to a large extent). But, without proper measure of the pH of the mulch, i am going to guess work on the garden lime to be added. I have ordered a highly reviewed "pH test strips" from amazon. Hopefully, they will provide some more clues. If i randomly add garden lime, and that increases the pH then i would have to find other ways to counter that effect; as far as i have read,

• Pros of lime : adds significant Ca & Mg in addition to raising the pH.
• Cons of lime: this would have the side effect of increasing the "chemical salts" in the soil, which have a counter effect on water intake of plant. Having salt in soil is against recommendation of many websites.

So far i have relied on the Calcium content in the bone meal & kelp meal that i am mixing into the soil. For Mg, i am relying on Epsom salt (on as needed basis). Your comments are appreciated.

"Even though tap water is alkaline, higher acidity value of moss should have brought the needle well below the reading i was seeing."

This is not necessarily true. Mixing a simple acid and a simple base of equal concentrations should give you a pH in between, but this system is anything but simple. The acids are weak organic acids, and the base is a carbonate buffer system containing both carbonate and bicarbonate. Buffered systems do not change pH linearly when acid or base is added.

You should really do this test with a 99 cent jug of distilled water if you want to get a result anywhere close to reality.

But let's get to your underlying issue. "The intention of the measure was to find out if i need to add garden lime to my mix (which consists of the mulch to a large extent). But, without proper measure of the pH of the mulch, i am going to guess work on the garden lime to be added."

Am I correct that you are concerned that using peat as a mulch will lower the pH of your soil too much, so you are considering whether to counteract it with lime?

What is your soil pH now?

Are you growing acid or alkaline loving plants?

What made you decide to use peat moss as a mulch? It can form a crust when it dries that will not absorb water very well, so it is not very good as a mulch.

tox, I believe sam is taking about using peat in a potting/container soil.....at least his other posts seem to indicate so...........

It all makes a lot more sense if it's a container mix! I was thrown off by the term 'mulch'.

Wanted to add the following info, for completion of this thread. Here is a laboratory test that shows how "temperature of water & amount of salt in water" can affect the pH measurement of wood chips. Though this paper is written about mulch, i guess the results can similarly affect pH of peat moss....

https://www.pulpandpapercanada.com/paptac/PDFs/Nov05/woodchips.pdf

That paper is about methods for lab testing of the pH of wood chips, and those effects are more related to the efficiency of extraction of organic acids from the wood chips than the measurement of pH itself. In other words, if you simply heat a solution to a different temperature, it should not change the pH solely on the basis of temperature. Same with ionic strength.

Thanks tox. Didn't read the paper in depth. I stumbled on that paper during my search for finding the pH for my store bought mulch and sphagnum peat moss (both were giving reading of 6.75 to 7.0 on my cheap pH meter from amazon). So, my interest was merely restricted to finding real pH of these, since internet search says they should be in the range of 3.5 - 5.5. Various efforts by me to get closer to this value failed. So, i concluded that my pH meter is not getting enough ionic strength to show true pH values of these two soils.

"my cheap pH meter from amazon"

There's your problem right there!! Unless a quality lab grade model ($$), pH meters are a waste of time and effort. You will get far more accurate results using the big box test kits and distilled water.

There are also some fairly accurate home-made test solutions you can make with things like vinegar just to check its accuracy, if you're interested. You can make one that's about pH 4, and distilled water should be 7. If those are way off, the meter is your problem.

It was not reading the pH of any liquids - only soil was recommended in that 2 prong tester. So, i did some digging into these meters and found that they need a bit of ionic solution in order to give correct readings. How much of H+ ions should be present for them to give correct readings is unknown. Numerous reports of people reporting on amazon that these type of meters do not measure pH of liquids they tried. So, i am not alone. Only an expert in the chemistry of these meters would give more insight on how to read pH of liquids that we prepare at home. I even tried it on well watered (with RO water) peat moss that was sitting in a cup for 10 days. That did not produce correct reading.

Ah, I see.

The amount of H+ is exactly what it is measuring though, so if that varies, the pH is literally varying as well. Perhaps they mean the soil moisture has to be high enough to get a signal from one probe to the other? Or, 'ionic' may refer to dissolved salts, rather than acid/base. Soil pore water does have salts in it (all kinds of dissolved miinerals). I wouldn't think a meter would require extra salt to measure a sample, that wouldn't make for a very convenient meter. In any case, the fact that these are known to be pretty inaccurate explains a lot.

Narrow range pH papers seem to be better for soil. 50/50 mix of soil and distilled water, stir, let sit 15 mins, and test the water.

Got a wide range pH (meant for testing urine) from Amazon. That had good reviews online, but at home testing, it proved to be inaccurate for store bought RO water and distilled water. Peat moss moisture came in the same range as others at around 5.5. The only thing that was accurately measured by it was my tap water - So, i am sending the paper tests back and planning on getting a good quality regent test now. From past years in another hobby i know La Motte is known for quality regents. They last only about 6 months and if stored properly 1 year i think. Most companies only guarantee 3 to 6 months. Thanks for any feedback you can provide.

Distilled and RO water have all of their salts, carbonates, sulfates etc. removed so they have zero buffering capacity, which means the pH will change just by looking at it crosseyed. In contact with air, CO2 will dissolve and form carbonic acid. That's why they use buffers, which are mixtures of a weak acid or base and a salt based on the same acid or base (conjugate pair) which resist changes in pH and are therefore much more stable in air, etc. Not surprised you had hinky results with distilled and RO water.

What if i add 2M solution of NaCl, in order to bring up the salt in the RO or distilled water ? Would that help ? I can not buffer the water much, because then my pH measurements would be affected - in my limited understanding. I have been resisting the time consuming process of making distilled water at home because i do not have the right set of utencils for it. That process was suggested in another thread.

While I applaude all the effort you are going to assess pH of both the bark mulch and the peat moss as accurately as you can, I am still kinda dumbfounded that you would go to all this work just to make a container potting mix!!

Just an observation :-)

:-) Many little projects are going on simultaneously, without affecting each other. I have the composting project, the DIY- raised bed project, tree pruning project, along with container pots project. Wish i had found the fun of gardening much earlier in life. Would have saved me a lot of trouble in life :-)