making soil acidic

charleslou23February 18, 2011

not sure if anyone tried this and works... i dig a hole and put some peat moss and maybe even pour some vinegar in the hole, would that make the soil a bit acidic eventually?

i'm trying this method first without using chemical or sulfur based stuff.

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Pouring vinegar onto the soil will lower pH instantly, within seconds. However, soil microbes exist that regard vinegar as food, so it will likely be consumed in a month or so. It turns out that soil microbes are involved in lowering pH with sulfur, although in a different way. When sulfur is added, nothing happens to soil pH immediately. Sulfur is not an acid. However, there are certain soil microbes that use sulfur as a food source, and these bacteria will multiply when sulfur is present. When the bacteria expire, the end result is sulfuric acid, and this does lower soil pH. It might take a year for all the sulfur to be consumed, but the pH does drop. It can remain at the new, lower level, for several years.

    Bookmark   February 18, 2011 at 6:30PM
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Skip the vinegar - it works too quickly, changes the pH too radically and breaks down too rapidly so the effect is lost in a matter of a few days to weeks. And because it is extremely acidic (pH of 2.4-3.4) it kills off beneficial soil organisms. Not much will tolerate that kind of pH.

Adding peat moss will help but so can various other soil amendments - compost and manures, cottonseed meal (a natural acidifier), aluminum sufate, ammonium sulfate, iron sulfate or just plain agricultural sulfur. Nothing wrong with that, either - it is an approved organic amendment.

None of these are especially fast acting so you need to plan ahead to alter soil pH well before planting.....about 6 months. And none will be a permanent fix. Depending on the buffering capacity of the soil, it will eventually revert back to its normal pH unless amendments are done routinely.

What is your pH now and what are you attempting to change it to?

    Bookmark   February 18, 2011 at 8:31PM
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If you go down the road of organic gardening(and i assume you do since you're here in this forum), at certain point of this road you will inevitably become compulsive composter, while using your own compost continually on your soil, and that act is what gives you a more or less permanent fix to all your alkaline soil problem 'cause compost raise soil ph, and i dont think you could give up this composting habit easily.

    Bookmark   February 19, 2011 at 4:23AM
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If Oak leaves (pH of 3.8) and pine needles (pH of 3.7) or maple leaves (pH of 3.2) do not significantly affect the soils pH why would Peat Moss (pH of 4.6)?
Understanding why a soils pH is what it is can help in changing it and a soils pH is where it is due to Hydrogen ions. Many and the pH will be acidic, below 7.0, too few and the soil will be alkaline, above 7.0. To change it you need to add something that will decrease the H ions (lime) or increase the H ions (sulfur, ammonium sulfate).
Getting sufficent amounts of organic matter into the soil will buffer the soil so the pH is of less concern.
I once added 3.8 cubic feet of Peat Moss to a 4 x 4 planting bed in an effort to lower the soil pH (5.7) for blueberries and after tilling the PM in and waiting a year a new soil test told me the soil pH of that bed was now 7.2, so I would doubt that Peat Moss does much of anything to lower a soils pH which I realize is contrary to what has been assumed for many years.

    Bookmark   February 19, 2011 at 7:00AM
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Peat moss - if one chooses to use it - is well known and thoroughly documented to be an effective product to lower soil pH. The reason it is able to do so while other acidic materials do not has to do with its nearly completely decomposd state. Decomposition, such as what will occur if the materials are incorporated into the soil, will effectively neutralize the acidic effects of things like oak leaves or conifer needles so their ability to alter soil pH is very limited.....virtually nonexistant. Peat moss OTOH retains its acidic properties when incoporated into the soil because it is pretty much already fully decomposed. The fact that it has virtually no nutrient value is also indicative of this.

According to a study done at the Ohio State University Agricultural Research and Development Station, the application of 2" or more of peat moss incorporated into the top 6" of the soil will lower pH by at least one unit within a single growing season. The effect can last as long as two years but soil pH will eventually increase unless other acidifying measures are followed.

    Bookmark   February 19, 2011 at 9:52AM
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Great thread everyone, I have a problem with my blueberries. They are not growing like (I think) they should. They are totally organic, so it is that the pH is to low or to high.
I will have a soil test done this Spring, but what to do after the test is another thing.
gardengal48, think you for defending your comment. I will search OSUA, for the study. And the different amendments to lower the pH. It should be easier here in South Carolina, then some Northern states, which have a natural high pH.
That in it self is why my problem maybe that the pH is to low & locking up the nutrient, slowing the growth.
I will start a thread on my finding when the test is done.

    Bookmark   February 19, 2011 at 11:42AM
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"If Oak leaves (pH of 3.8) and pine needles (pH of 3.7) or maple leaves (pH of 3.2) do not significantly affect the soils pH why would Peat Moss (pH of 4.6)? "

Because the oak leaves, maple leaves and pine needles are going to decompose and the peat moss has already decomposed, so it's far more stable.

    Bookmark   February 19, 2011 at 1:57PM
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So, gardengal, why did the pH of the soil in that plot go from 5.7 to 7.2, from an acid reaction to an alkaline reaction after adding Peat Moss to that bed? The amount would have been more than that OSU study used.
If that OSU study is on line it has not appeared in my research.

    Bookmark   February 20, 2011 at 7:01AM
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Is this the OSU study you're looking for kimm?

"...the pH in peat-moss amended plots was decreased by one full unit, and this effect lasted at least for the entire growing season."

also referenced to here.

" According to one source,[2] an application of 2 inches of sphagnum peat moss incorporated into the top 6 inches of soil will lower the soil pH by one unit or more within a growing season. The positive effects of sphagnum peat can last two or more years, but unless other measures are used the pH of the soil will eventually increase."


    Bookmark   February 20, 2011 at 10:01AM
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kimmsr, I have no idea why you got the results you did as I have no way of knowing what - exactly - you added to your soil other than peat moss. And I'd have to question why, if your soil was already at a pH of 5.7, you bothered to add peat moss at all.

But your particular experience is contrary to all other documented sources that have pretty firmly established peat moss's ability to lower soil pH.

Personally, I tend not to put a lot of weight on anecdotal reporting.

    Bookmark   February 20, 2011 at 10:16AM
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Hi Lloyd, good to here from you.
I checked out the link,thanks.

    Bookmark   February 20, 2011 at 11:32AM
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Nothing but peat moss was added at that time and was added to try to lower the soils pH to 4.something which is strongly recommended because chlorosis can occur in blueberries in soils with a pH as high as 5.5.
Whether that is what I am supposed to be looking for or not I have no idea, but what I read there is that those people added peat moss and sulfur and sulfur is something one does add to soil to lower the soils pH. And every study I have seen about Peat Moss lowering a spoils pH also had sulfur, or ammonium nitrate, added to the soil, not just Peat Moss.

    Bookmark   February 21, 2011 at 8:21AM
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Xtal(z8b Temple. TX)

Got a question for you.

What is your water? If your water is alkaline, I'm not sure that trying to adjust your soil toward acid will help very much. You might want to call your local Ag agent in your county to see what difference it would the water would make.

Just a thought.

    Bookmark   February 21, 2011 at 8:51AM
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Then I guess I was reading "Table 1. Soil pH Values Over a Two-Year Period in Treatments Without Sulfur" incorrectly, my bad.



    Bookmark   February 21, 2011 at 8:57AM
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wonder if i should stick with planting BB in pots instead of in ground since lowering soil's PH permanently and quickly seem pretty difficult...?

i havent buy a ph tester yet but i'd guess my soil is around 7ish.

    Bookmark   February 22, 2011 at 1:44PM
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charleslou, the attempt to change a soil's pH has merit....if one has a reason to do it.
You wish to use no chemicals.....and then say you wish to dump vinegar into a hole. I'd like to suggest that that vinegar you think is non-chemical is quite the contrary.

Fooling around with quick solving material might just kick you in the apse.....
You speak of not wanting to use sulfur.....why not?
Its been around since the world began and is the most trusted method to change a soil's pH....
Yes, its a chemical.....well, let's hope it is, our world would not be the same without it.

    Bookmark   February 25, 2011 at 7:09PM
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I tested my clay soil in a couple of small bare spots with an old "Environmental Concepts" pH analyzer. It's an inexpensive probe which apparently measures a small current or voltage on a pH scale. I moistened the soil with tap water and took a reading (about pH 7). With the analyzer still in ground, I watered again with 2 Tbs white vinegar per gallon. The change in reading was immediate with pH falling to the low limit of the acid side of the scale. Then slowly the reading swung back towards neutral, stopping at 6.5. Then I watered some plants this way (which are in poor shape anyway) to see if they would stand up to it.

    Bookmark   June 13, 2012 at 7:56PM
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blazeaglory(10 SZ22/24 OC Ca)

This works fine and is elemental sulfur and gypsum. I use it for my Citrus. My soil was Ph 7.7 when I first added it about 2 months ago, now my soil is a little above 7. I figure at this rate my soil should be where I need it by the end of the year. I might have to add more though. I also added and organic blend of food and bacteria so I think that is helping also. They do have directions for blueberries.

    Bookmark   June 14, 2012 at 12:43AM
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Would LEYLANDII cuttings make the soil acidic i have just planted a hydrangea, im pretty new to gardening so any advice would be great

    Bookmark   September 15, 2013 at 2:57PM
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Probably not - see link below.

Do you know what your soil pH is currently? How about calcium level, water hardness and pH?

Here is a link that might be useful: Pine Needles Cause Acid Soil - Fact or Fiction

    Bookmark   September 15, 2013 at 5:03PM
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blue_skink(z3 MB Cda)

Has anyone heard of a powdered food supplement called MSM? It is a form of sulfur. If, as someone above stated, certain soil microbes use sulfur as a food source and the end result is sulfuric acid, which lowers the pH, then maybe this would work, too. Any opinions? Thx.

    Bookmark   September 23, 2013 at 5:40PM
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Sulfur, as in garden sulfur, can be used to lower soil pH. The mechanism is as you describe - soil microbes oxidize the sulfur and in the process with water it effectively becomes sulfuric acid. However, for it to work you can't have an excess of free lime present in the soil, and any irrigation water needs to be fairly low in carbonates.

    Bookmark   September 23, 2013 at 8:27PM
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blue_skink(z3 MB Cda)

Thanks for your info, but how are we supposed to know if there is an excess of free lime or not? I know what the pH of the soil is (8) but that is not automatically due to lime, is it. There might actually be v. little lime in the soil. Is there some kind of home test one can do.

    Bookmark   September 23, 2013 at 8:45PM
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Home test ? No. You might check with local ag folks - they should have a good idea of what your soils are like. But if your native soil pH is 8, and your water is hard with calcium carbonate, then it is most likely your soil has excess free lime (meaning undissolved calcium carbonate) in the soil.

This post was edited by TXEB on Tue, Sep 24, 13 at 18:25

    Bookmark   September 23, 2013 at 9:12PM
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toxcrusadr Clay Soil(Zone 6a - MO)

I would think a lab soil test that includes Ca would tell you that, if I understand TXEB correctly. Typically you get P, K, Ca and Mg results and the lab tells you whether they are low, OK or too high.

MSM (methylsulfonylmethane) appears to be a dietary supplement claimed to help with arthritis and other health issues but not approved by FDA for any uses. It would likely be much more expensive than powdered elemental sulfur. Powdered sulfur works fine for pH adjustment.

    Bookmark   September 24, 2013 at 12:57PM
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blue skink - first, here is a reference from Colorado State University via their Master Gardner program that may help explain the issue of free lime, which is undissolved calcium carbonate in soil, a bit better.

To get an idea of what is characteristic for your soil in MB, you can check out the Manitoba Soil Series here.

I just looked at the Newdale Series, which is the official soil of the province, and it is described as a calcareous clay loam with a pH @ 7.2. Calcareous means mostly or partly composed of calcium carbonate, which translates to limestone or chalk. With your pH of 8, I suspect your soil has abundant free lime. It will be very difficult to effectively lower your soil pH in the near term. If you use irrigation water and it has an alkaline pH, then it will be extremely difficult.

This post was edited by TXEB on Wed, Sep 25, 13 at 8:44

    Bookmark   September 25, 2013 at 6:52AM
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blue_skink(z3 MB Cda)

I need P for my Tulips, that's what this is about. I thought just adding S would do the trick. I thought acidity=acidity, and it doesn't matter WHAT creates the acidity. But I looked on my latest soil test and it says "Sulphate - S: Excessive".

Thank you kindly to the both of you for your links and help.

    Bookmark   September 25, 2013 at 9:53PM
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If you want to boost P levels while at the same time trying to lower pH you want to look for ammonium phosphate. It may be used as both an N and P component in various formulated fertilizers, or you can look for it as a stand alone and account for the N it brings. Some "starter" fertilizers use ammonium phosphate as a key component. You want to avoid, to the maximum extent possible, rock phosphate and triple phosphate.

So, I'm curious, what else did your soil test tell you about your soil? Part of my interest is that your soil and mine in coastal SE TX likely have similar geophysical origins from about 75 million years ago.

    Bookmark   September 25, 2013 at 10:06PM
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blue_skink(z3 MB Cda)

That is interesting that our soils, though located so far apart, have the same origins. However, Manitoba has several different soil zones, very different. This pocket where I live, not a large one, has sandy soil. Lots o' gravel pits near here.The soil in my garden was hauled (by me, from no deeper than 9") from wild, virgin land a short distance away from our house (1/4 mile), since my garden, near the house, was once a sod farm so the top soil was stripped.

I didn't have our soil tested for Ca, Na or Mg for some reason. Wasn't interested at the time! Nor did I request Texture, but I can assure you it's Sandy soil. The results I have are:

Nitrate Nitrogen: Marginal 14 ppm
Phosphate: Deficient 4
Potassium: Optimum 187
Sulphate Sulfur: Excessive >20
Iron: Optimum 206
Copper: Optimum 1.5
Zinc: Optimum 5.5
Boron: Optimum 2.8
Manganese: Optimum 20.8

pH: 8
Salinity: Okay - .6
Organic matter - 27.9%

So that is my sad story where soil is concerned!

Wish I understood things better, e.g. why would ammonium phosphate be a good choice but not triple phosphate. Also, what if I want to avoid chemicals from a bag. I'm not rigid about this, though. Also, I have a bit of liquid phosphoric acid on hand (purchased for another reason) and wonder what you would think of me diluting this and using it to put into the tulip holes. To grow nice potatoes here, I put diluted vinegar into the planting holes and get very good crop, no insect problem, no scab in spite of soil being pH of 8!

Tks for your interest in helping out and I'm curious as to your particular soil profile, too.

Also, what is "free lime" as opposed to the Ca reading you get from a soil test?

    Bookmark   September 26, 2013 at 3:27AM
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We have similar origins, but the soils down here never saw any glacial action. The basis is both were covered by the Western Interior Seaway (use google), that included the Hudson Seaway in Canada. That's why the soils are calcareous - the now lands were former sea beds. Our typical soil Ca levels here are ~ 5,000 ppm near the surface, but subsoils can go into the 2-3% range. Typical pH is ~8. Our soils around here are mostly clay, but we have pockets that are sand pits. Still, the Ca levels run ~ 5000 ppm.

Free lime is basically undissolved calcium carbonate in the soil (chalk/limestone). That's why the pH is high. With the abundance of free lime in the soils, there is little you can do to lower the pH in a lasting way. There's always more limestone already there.

From your analysis three things jump out at me. One is the iron level, which I suspect is a typo (20.6 ?). The second is your micros (iron, zinc, copper, manganese) are generally high. Third is your organic matter is out of sight -- 27.9%. Is that right? If you raided the woodlands for soil that might explain a lot of that. Have you added any amendments, manure or compost of any kind?

The reason I suggest ammonium phosphate is because it is a Ca free source of P. You most likely already have a lot of Ca. On calcareous soils the frequent reason for low P is that the dominant form of P in soils, orthophosphate, combines with Ca to form insoluble complexes headed for apatitie. It is a very slow process, but nonetheless it occurs. Over a period of ~ 9 years my base soil P levels have gone from excessive at ~100 ppm to 10 ppm. The conversion is aided by the fact that my irrigation water (municipal water) contains about 100 ppm of calcium carbonate. The last thing I want to add to my soil is more calcium, especially if I want to raise P levels. Ammonium phosphate is a preferred route. It also is acidifying, which helps.

Phosphoric acid would work too, and would do even better on the acidification. But the pure stuff (85%) takes a lot of dilution and well controlled application. It does have the added benefit of a stronger and more lasting pH reduction.

BTW, to me sulfur at 20 ppm is high, but mine is ~ 40 ppm, and is not characterized as "excessive". I believe you can relax about the S.

    Bookmark   September 26, 2013 at 6:19AM
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blue_skink - I know nothing whatever about soils but if you are just concerned about your tulips the soil is not massively important since the bulbs you buy already have all the nutrition in them which the tulips need to flower. You could even grow them in plain water if need be. Only if tulips perennialise in your garden and thus need to build up flowers for next year is the soil of much importance. Even then they tolerate a wide range of soils and are not particularly fussy.

    Bookmark   September 26, 2013 at 7:06AM
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blue_skink(z3 MB Cda)

Hello, TX. Thanks for all your interesting info! Yes, Iron reading should have been 206. You are pretty smart about these things. You can even see my typing errors!

You say that my micros are generally "high", but the lab classified their quantities as "optimum".

Thanx for your opinion on the sulfur. They are talking about Sulphate, right? Maybe there are other forms of S in soils?

I raided an area on our property that is fairly near a forest. Is all that org. matter a bad thing? I wondered about that, because people who have low org. matter knock themselves out trying to fluff theirs up!

So, to make a long story short - it's not about absolute amts of P or S, but, rather, free Ca??

Regarding watering: I use rain water from the barrel for as long as I can but then but by around August or so there tends to not always be enough rain.

I add a bit of chicken manure mixed with straw that has partly broken down outdoors during the spring/fall/winter. Also partly decomposed kitchen wastes that break down pretty quick in the spring.

Finished compost in huge amts is supposed to solve everything, but I wonder...

Oh, one more thing. I read FWIW that no soil anywhere on earth is perfect for agriculture or gardening. In one way or another, they are out of balance. However, whoever said that doesn't consider that not all crops want the same things.

I know nothing about soils but I could read and discuss it all day in the hopes of learnig about my own. So glad you and others are here to help out.

Flora - I have tried to grow Tulips in the past. They'd do good for the first year, as you mention, because the bulb has food in it. But I want them to keep on going. That is why I'm concerned about acidity, Phosphorus, etc. Thank you so much for your info.

    Bookmark   September 26, 2013 at 12:05PM
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Tulips are hard to keep going in many areas. I don't think it has a lot to do with soil but more to do with the type of tulip and your climate. Failure of tulips to return is largely a matter of giving them cold winters, hot dry summers and sharp drainage. Obviously you will get sufficient winter chill, so that won't be an issue. The old fashioned Darwins and some of the species are the most dependable. Aside from your soil discussion here you might want to post your tulip query on the Bulb Forum here on GW. Notice that there is no mention of acidity in this article.

Here is a link that might be useful: Getting your tulips to come back.

    Bookmark   September 26, 2013 at 5:08PM
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blue_skink(z3 MB Cda)

Thanks so much for the link! I think maybe I was trying to grow the wrong varieties. Yes, it's true, our climate here is darn near perfect - cold winters, hot dry summers. And I strive to provide good drainage.

Still, I don't like our superalkaline soil. Geeeze, I could make soap out of it. There is something magical, too, about compost. It seems to have a balancing effect on too-acid or too-alkaline soil.

    Bookmark   September 26, 2013 at 6:12PM
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blue skink - tulips aside, my characterization of your micros as high is based upon current TAMU critical levels for those nutrients. That may well be an inappropriate view for your soils in your environment. The fact is the values determined via analysis are quite dependent upon the method employed, and can vary a good bit between different methodologies. Whether levels are low or high should be based correlation studies between plant response and the nutrient levels determined by specific methods (often called calibration). So long as your analysis was done by a lab using method suitable for your soils and the interpretation is based upon matching plant calibration studies, stick with that.

BTW - willing to share who did the analysis?

On S- the most common form in aerobic soils is sulfate. But if the method of analysis is based upon ICP, it will typically include other forms of S that were extracted along with sulfate, including different inorganic forms or organically bound S. The number on your soil report should represent the amount of elemental S accounted for by the method of analysis.

On P - the same is true for P as S. The dominant form in soil is orthophosphate. But their are other inorganic forms as well as organically bound P. Depending upon analytical method what is seen may be orthophosphate or may include those other forms.

The play between Ca and P is that in calcareous soils Ca will, over time, sequester phosphate by combining with it into intractable forms that will not show up in the analysis, nor will they contribute to either Ca or P available nutrient levels for plants. For both Ca and P those complexes are considered "fixed" forms of the nutrient element. What is important for plant nutrition is that which will be available for plant consumption. Soil test methods are developed to reflect the levels in soils that plants can access, not the total elemental content of the soil. I suspect you have way more P in your soil than your analysis shows. That extra, in principle, will not be available for plant nutrition. That's the fixed P.

This post was edited by TXEB on Fri, Sep 27, 13 at 9:05

    Bookmark   September 27, 2013 at 9:04AM
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blue_skink(z3 MB Cda)

"Soil test methods are developed to reflect the levels in soils that plants can access, not the total elemental content of the soil."

I'm glad you mentioned the above. I would never have considered this. It would be interesting to know, tho, just how much P my soil has, just for the hellofit. They say that P is the most underrepresented agricultural mineral in the world, that there's few places that have a lot, free lime content notwithstanding.

I had my tests done at Norwest Labs in western Cda. I think they are pretty good, they came highly recommended to me.

    Bookmark   September 27, 2013 at 7:49PM
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"It would be interesting to know, tho, just how much P my soil has, just for the hellofit."

You can get that done, and with the right lab it's not all that expensive. If you could figure out a way to get a sample to NY (lot's of hoops to jump through importing soil into the U.S.), Cornell offers two versions of a Total Elemental Analysis. The time-honored traditional method goes for $35 - includes determination of total Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Se, Sr, Ti, V, and Zn. A newer version of the test goes for $17.

Here's a link to the Cornell Soil Analysis submission form. Scroll down on the second page to "Total Elemental Analysis/Heavy Metal Screening", see tests 2020 or 2021.

You might check with the lab that did your work to see if they offer something comparable for a reasonable fee.

Now the question I always asked folks who came to me saying they wanted to know if they had any of X in their soil/water/food/etc. ... What will you do with the data? Think through it - what if the answer is A, or B or C - what would you do? How does it help you to know? Is there anything you would or will do as a result of knowing? Does an answer, at any level, one way or the other, lead to action in any way, on your part? It's generally a good idea to know what you will do with the result before you ask for the test.

Here is a link that might be useful: Cornell Soil Testing Submission Form

    Bookmark   September 27, 2013 at 8:14PM
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