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Lightweight Peat's Mucky Muck soil testing
- Thread starter biggreg
- Start date
biggreg
Member
Has anyone called their soil lab and asked if their last soil test had an accurate measurement of the required sample mass?
Did you ask for a retest?
If they say it was a volumetric test, did they use the 2.5cm3 scoop and 25ml solution? Did they report it in volumetric units?
Did you ask for a retest?
Did you lab convert to lbs per acre without measuring the density of an obvious to any knowledgeable soil lab tech lighter density soil?
Why would they assume standard density for a sample of peat?
Why would an errant assumption value be allowed on your report?
Does anyone want to know their soil's real CEC?
Would you like to check Mehlich 3 cation summation CEC against a direct measurement CEC for a more accurate starting point to balance your soil?
Wouldn't you like to know the mass of your potentially plant extractable elements per the volume of your container vs the mass of them per a mass of dried soil?
Wouldn't you like a larger sample size analyzed per test?
At least 2g/20ml
But
Why not 2.5g/25ml for the Mehlich 3?
Did you ask for a retest?
If they say it was a volumetric test, did they use the 2.5cm3 scoop and 25ml solution? Did they report it in volumetric units?
Did you ask for a retest?
Did you lab convert to lbs per acre without measuring the density of an obvious to any knowledgeable soil lab tech lighter density soil?
Why would they assume standard density for a sample of peat?
Why would an errant assumption value be allowed on your report?
Does anyone want to know their soil's real CEC?
Would you like to check Mehlich 3 cation summation CEC against a direct measurement CEC for a more accurate starting point to balance your soil?
Wouldn't you like to know the mass of your potentially plant extractable elements per the volume of your container vs the mass of them per a mass of dried soil?
Wouldn't you like a larger sample size analyzed per test?
At least 2g/20ml
But
Why not 2.5g/25ml for the Mehlich 3?
biggreg
Member
Let's look at the "scoop" vs. balance measured test side by side again.
Yes the cation balance is close on all samples. The dilution ratio didn't have much effect knocking loose the cations but look at Phosphorus.
Phosphorus is extracted via a differing mechanism vs the cations. The acetic and nitric acids work with the flouride in Ol' man Mehlich's sauce to extract P that indexes well to crop response. The dilution ratio is critical for this process.
Have a look for yourself.
The more sauce and the less soil, the more phosphorus that double acid dissolves.
How can a fella work with a scooped mystery ratio test? How can you balance P to K or to whatever you balance it to?
Look at the differing amounts of P a fella would amend according to these tests.
Is your tested and balanced soil really balanced?
biggreg
Member
The ammonium in the sauce replaces the cations attached and knocks them loose. Doesn't matter how much ammonium is used, it can only displace the cations that are attached.
The nitric and acetic acids solublize the Phosphates. The more acid to soil, the more gets solublized!
The fluoride compelxes with Al, increasing the P in the sauce and the acetic keeps it buffered to a low ph to keep calcium floride from forming.
The EDTA chelates the micros and is also ratio dependent.
Ol' man Mehlich has a recipie. Follow it!
No more mystery ratios please!
The nitric and acetic acids solublize the Phosphates. The more acid to soil, the more gets solublized!
The fluoride compelxes with Al, increasing the P in the sauce and the acetic keeps it buffered to a low ph to keep calcium floride from forming.
The EDTA chelates the micros and is also ratio dependent.
Ol' man Mehlich has a recipie. Follow it!
No more mystery ratios please!
biggreg
Member
No soil scientist, no argonomist, no lab chemist at any lab any where in this country could make any intelligible logical argument in defense of using a NCR-13 "2"or especially "1" gram, mineral soil density 1.7 or .85 cm3 volume scooper as the correct measuring tool for the mass of a soil sample siginificantly less dense than the design density of that scoop in this Mehlich 3 soil test.
NONE!
No one can argue that a non published, experimental, random, non-spec, mystery Mehlich 3 extract solution to soil sample mass ratio counts as a legit Mehlich 3 test.
No one!
No one can balance anions or micros with ratios using a scoop measured test on lightweight soils.
Look at the side by side.
NONE!
No one can argue that a non published, experimental, random, non-spec, mystery Mehlich 3 extract solution to soil sample mass ratio counts as a legit Mehlich 3 test.
No one!
No one can balance anions or micros with ratios using a scoop measured test on lightweight soils.
Look at the side by side.
I've been getting ammonium acetate tests at ph7 for a few years but I'm being told melich 3 is a better way to go in the future. That's crazy there isn't some sort of testing standardization for soil labs.
biggreg
Member
The AA7.0 extraction and the Mechlich 3 should report very similar base cations.
The Mehlich 3 has the bonus of extracting The anions and micros with the same test.
The written standards, appropriate tests, and know how already exist.
The Problem is lightweight soils have been ignored because we've been such a minority.
We will continue to be ignored unless we speak up.
I've complained to the NAPT oversight comittte asking for some lightweight soils standards and guidance for the soil test industry. I'm waiting on some follow up after assurances our issues would be discussed at the regional meetings. They asked to use my side by side for a talking point.
The Mehlich 3 has the bonus of extracting The anions and micros with the same test.
The written standards, appropriate tests, and know how already exist.
The Problem is lightweight soils have been ignored because we've been such a minority.
We will continue to be ignored unless we speak up.
I've complained to the NAPT oversight comittte asking for some lightweight soils standards and guidance for the soil test industry. I'm waiting on some follow up after assurances our issues would be discussed at the regional meetings. They asked to use my side by side for a talking point.
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biggreg
Member
Seems scientist here in North America like to use "organic soils" interchangeably with histosols.
Seems a likely source of confusion. When I hear "organic soils", I think of any soil that is fertilized with organic approved fert not a peat deposit or an over 20% organic matter lightweight soil.
I prefer the Australian term for peaty soils.
Organosol sounds more soothing than histosol and isn't as likely to confuse as using "organic soils".
http://soilscienceaustralia.com.au/iys-blog/343-iys-soil-of-the-month-oct
Seems a likely source of confusion. When I hear "organic soils", I think of any soil that is fertilized with organic approved fert not a peat deposit or an over 20% organic matter lightweight soil.
I prefer the Australian term for peaty soils.
Organosol sounds more soothing than histosol and isn't as likely to confuse as using "organic soils".
http://soilscienceaustralia.com.au/iys-blog/343-iys-soil-of-the-month-oct
biggreg
Member
Q: so what if we looked at the scooped tests as volumetric scooping and not mass measuring? Won't that work?
A: No
Why not?
A: 1.17647059
Q: what's that?
A: multiplier to convert the units ppm per L of test solution to units of mg/L soil.
Q: how you figure?
A: 20ml solution per 1.7cm3 soil in a "2g" scoop. If the test was designed to be the volumetric version, the multiplier to convert units would be 1 ( 25ml/2.5cm3)
The SERA lab manual has the equations.
The test value after correcting multiplier is in mg/L of air dried and ground soil. The mg/L in your field moist volume would be maybe 1/2 of that value.
It's still an off ratio and undersized sample so quit trying.
Do it the right way.
Mg/L of air dried and ground soil isn't the relevant unit of measure
Mg/L field moist soil is the relevant unit
A: No
Why not?
A: 1.17647059
Q: what's that?
A: multiplier to convert the units ppm per L of test solution to units of mg/L soil.
Q: how you figure?
A: 20ml solution per 1.7cm3 soil in a "2g" scoop. If the test was designed to be the volumetric version, the multiplier to convert units would be 1 ( 25ml/2.5cm3)
The SERA lab manual has the equations.
The test value after correcting multiplier is in mg/L of air dried and ground soil. The mg/L in your field moist volume would be maybe 1/2 of that value.
It's still an off ratio and undersized sample so quit trying.
Do it the right way.
Mg/L of air dried and ground soil isn't the relevant unit of measure
Mg/L field moist soil is the relevant unit
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biggreg
Member
The Mehlich 3, if executed correctly, will give a report on the mg of element per kilogram of dried,finely ground soil. It will give values for the cations it displaced from your exchange sites , anions it solubized and micros it chelated to values that all have demonstrated to index well to plant responses in a wide variety of soil including peaty soil.
Real easy to execute this test correctly. The first step is a proper sample mass and measurement of that mass into the flask.
Second is a proper ratio of Mehlich 3 solution to that soil mass.
Seems blazingly simple to me. How to follow a recipe 101 type shit.
Real easy to execute this test correctly. The first step is a proper sample mass and measurement of that mass into the flask.
Second is a proper ratio of Mehlich 3 solution to that soil mass.
Seems blazingly simple to me. How to follow a recipe 101 type shit.
biggreg
Member
From the values reported in mg per kilogram of dried, ground soil from a properly executed Mehlich 3, we need to know what field moist volume contains a kilogram of that soil if we are to put the soil test measurement to use.
We must measure a volume of field moist and then dry it to the same level as the test sample( air dried per specs) and measure mass to get to relevant units. Bulk density.
The usda soil survey lab manual shows various bulk density tests. They report in oven dried mass/field moist volume. They also give an airdry mass/ oven dry mass ratio to use as a conversion if needed.
We must measure a volume of field moist and then dry it to the same level as the test sample( air dried per specs) and measure mass to get to relevant units. Bulk density.
The usda soil survey lab manual shows various bulk density tests. They report in oven dried mass/field moist volume. They also give an airdry mass/ oven dry mass ratio to use as a conversion if needed.
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biggreg
Member
The way it should be:
Good sample mass
Good sample to solution ratio
Good bulk density measurement
Good relevant volumetric reporting units
The way it is:
Bad sample mass
Bad sample to solution ratios
Bad buik density assumption
Bad per mass and per volume reporting units
If one just has to stick with a bad scoop job at least don't pay for any extra micros and forget your Phosphorus and Sulfur values.
Good sample mass
Good sample to solution ratio
Good bulk density measurement
Good relevant volumetric reporting units
The way it is:
Bad sample mass
Bad sample to solution ratios
Bad buik density assumption
Bad per mass and per volume reporting units
If one just has to stick with a bad scoop job at least don't pay for any extra micros and forget your Phosphorus and Sulfur values.
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biggreg
Member
Found this nugget in the north central lab manual on a copper test for organosols:
"The 1 M HCI extraction for Cu currently being used in Michigan is for organic soils (7) and is not rec- ommended for use on mineral soils. The procedure presented here is the procedure used at the Michigan State University, Soil and Plant Nutrient Laboratory."
It is a per mass test. I wonder how it compares to a Mehlich 3 copper test on organosols?
"The 1 M HCI extraction for Cu currently being used in Michigan is for organic soils (7) and is not rec- ommended for use on mineral soils. The procedure presented here is the procedure used at the Michigan State University, Soil and Plant Nutrient Laboratory."
It is a per mass test. I wonder how it compares to a Mehlich 3 copper test on organosols?
biggreg
Member
If you ever hope to compare the two tests, your Mehlich better have had the sample mass weighed in.
The Michigan copper test spec says:
"2. Weigh out 2.0 g of soil and transfer soil to a 50 mL Erlenmeyer flask."
No scoop option on this one.
Plus one could look at Michigan State's organosol SLAN data for copper.
Love to see a side by side with a Mehlich 3
It would ONLY be comparable if the Mehlich 3 was not ignorantly SCOOP weighed with the wrong measuring tool.
The Michigan copper test spec says:
"2. Weigh out 2.0 g of soil and transfer soil to a 50 mL Erlenmeyer flask."
No scoop option on this one.
Plus one could look at Michigan State's organosol SLAN data for copper.
Love to see a side by side with a Mehlich 3
It would ONLY be comparable if the Mehlich 3 was not ignorantly SCOOP weighed with the wrong measuring tool.
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