Slownickel lounge, pull up a chair. CEC interpretation

[orechron]

I don't think I could spray enough Ca or often enough right now. I need to get my soil right again. I still want to get to a point with a high cec mix where I don't have to spray anything. Seems like we've been chasing that for a while. Maybe it's unrealistic, without additional hormones or chitin for example. Too good to not use.

Hey Slow:


I might make it

 

[caterpillar710]

Can't be not spraying

 

[jidoka]

Including micros if you have off the charts P

 

[Avenger]

Therefore, to achieve accurate CEC measurements of calcareous sand-based samples only double extracting techniques should be used and ECEC estimates should be avoided.

When measuring the CEC by double extraction (CaCl%/Mg(N03)z and NaOAcNaCl/Mg(N03)2), the CEC ranged from 1.1 to 2.0 cmolc«100g"' and 1.6 to 3.0 cmolc lOOg".........................................................................................,10.6 cmolc-100g"' using NH4OAc pH 8.1................................................... 124.1 cmolc-lOOg"1 using Mehlich 3

quote source:link

Notice they say estimating CEC by summation of the extracted cations should not be used. They do not, that I have seen, ever recommend to use the [email protected] extraction results instead of Mehlich3 to estimate the CEC or calculate base cation saturation ratios. Doing so does indeed result in much less over estimation, but it is far from accurate.

I'd like to see a “barium chloride compulsive exchange method” determination of effective CEC compared to the estimated CEC from summation of the extracted cations for one of the common light weight high organic matter mixes. Then at the very least we might have an idea how grossly over estimated the CEC is that everyone is working with.

 

[slownickel]

quote source:link

Notice they say estimating CEC by summation of the extracted cations should not be used. They do not, that I have seen, ever recommend to use the [email protected] extraction results instead of Mehlich3 to estimate the CEC or calculate base cation saturation ratios. Doing so does indeed result in much less over estimation, but it is far from accurate.

I'd like to see a “barium chloride compulsive exchange method” determination of effective CEC compared to the estimated CEC from summation of the extracted cations for one of the common light weight high organic matter mixes. Then at the very least we might have an idea how grossly over estimated the CEC is that everyone is working with.

Avenger,

What you are quoting is about sand based greens on a golf course, not mixes of compost, peat, minerals, worm castings, lobster shells and organic left overs from the previous season.

 

[Avenger]

yes, i know

but is it not the basis for your use of [email protected] iinstead of Mehlich3?

 

[jidoka]

Spectrum uses mehlich 3 with a fudge factor to correlate with what they call chemical analysis

 

[biggreg]

I've recently realized the labs are using the dreaded "scoop" and calling it 2g on the Mehlich 3 tests I've been looking at. No wonder I could only move the ppm by weighing in amendments as if it were field soil density.

Looking into this, the Mehlich 3 standard is weigh 2.005+/- grams of soil per 20ml extract solution. When the labs use a scoop for lightweight soils, the dilution ratio of soil to solution is vastly different. Instead of 2g per 20ml, it could be 1/2 to 1/4 gram per 20ml. I came across a study of the effects of dilution ratios on the Mehlich 3 report that suggests Dilution ratios matter. The scoop is bad science.

The same lab would always report ph higher than my in house testing. They say they test 1:1 volume of soil to distilled water. 1:1 weight soil to water is what we need for lightweight soils. 1:1 volume is close to 1:1 weight in field soil so it works without the need to actually weigh the soil.

What the labs are doing is close enough, I guess, for a 2 million pound acre but as the containers gets smaller, the need for precision goes up.

Currently looking for a lab that owns a real balance and tests real, not imaginary soil.

 

[biggreg]

The original published Mehlich 3 called for volumetric reporting. It used a 2.5cc scoop and 25ml solution. I can work with volumetric ppm ( unknowingly have been with these standard scoop tests!) but i believe Mehlich had field soil in mind with a smaller range of densities. With our 1/4 to 1/8th weight soils, to get a test close to the correct ratio of soil to extract, we should probably weigh in the correct grams

 

[jidoka]

I just added a note on a spectrum test asking them to weigh my sample. My kinda coot mix weighed 1/2 what field soil weighs. That means 1 lb per acre furrow slice is 1 ppm, not 1/2 ppm. Semi important if you are trying to raise zn ppm by 10 or whatever

 

[slownickel]

The original published Mehlich 3 called for volumetric reporting. It used a 2.5cc scoop and 25ml solution. I can work with volumetric ppm ( unknowingly have been with these standard scoop tests!) but i believe Mehlich had field soil in mind with a smaller range of densities. With our 1/4 to 1/8th weight soils, to get a test close to the correct ratio of soil to extract, we should probably weigh in the correct grams

CEC per volume from a scoop is telling us exactly what is in that volume of soil, I agree.

And one of the reasons behind all this testing, especially good vs bad etc.. was to see if the base distribution concepts held up or not, and they did!

A good field with 7 to 10% OM is no different that what is in these hybrid mixes. Compost, worm castings, peat, etc.. all these add up. Are we off maybe a bit, of course. However, have the numbers been holding up? Just read everyones response so far to applying gypsum where they all thought they had enough Ca from the carbonate sources (just like in a soil). Asking them if they know a better way to get the responses that they have seen.

I have worked ornamental plants in pure rice hulls so we could ship rooted plants with no soil. That is a medium. No humus. Pure peat or coco, that is a medium, right up til it decomposes, in which case it converts to a hybrid soil.

So far, M3 and [email protected] has been nailing it.

This idea of specific density is ok, but not sure what we are going to learn from there as the levels of nutrients are so high that we are seeing, the only chance we have is to balance them making calculations on basis of some real numbers.

Let's do it this way. Show us a real alternative method that will give us the same gypsum recommendation that has been working. I am eager to learn. But this density idea to me is somewhat worthless if we are talking about a soil, which I believe we are as there are humus molecules at work. In medias, that is not the case.

I am all ears.

Thanks for chiming in and welcome!

 

[slownickel]

I just added a note on a spectrum test asking them to weigh my sample. My kinda coot mix weighed 1/2 what field soil weighs. That means 1 lb per acre furrow slice is 1 ppm, not 1/2 ppm. Semi important if you are trying to raise zn ppm by 10 or whatever

Your furrow slice showed exactly what is in it. Not half.

Why?

Because the measurement was by volume, not by weight. ABOVE UNCHANGED READ UPDATE BELOW.

Just got off the phone with the head guy in the lab that actually does the testing. Interesting conversation. I was wrong. It happens and I apologize.

Please ask the lab to make the sample with 1 gram in your request to the lab. This is critical not because of the density of the sample, it is critical at the chemistry level! The number is not double or half!

With that said, the lab guys said that my argument is not wrong, the density isn't the issue. What is the issue is the calibration of the reactants against so much soil. Those are curves, they are not linear relationships. So density really is meaningless. What is critical is the weight vs reactant calculation.

Thanks Biggreg and Jidoka for making me get off my ass.

 

[jidoka]

But my amendments of micros would be double what i was shooting for if i didnt know better.

Ratios work cause the cec is under reported.

Ppms...say P...can be off a fuck load

 

[slownickel]

But my amendments of micros would be double what i was shooting for if i didnt know better.

Ratios work cause the cec is under reported.

Ppms...say P...can be off a fuck load

Read my amended post above. You were quasi correct!

 

[jidoka]

Apparently you will never get my point. I do not amend by feel. I want accurate data.

It is ok though i will stay out of this thread

 

[slownickel]

Apparently you will never get my point. I do not amend by feel. I want accurate data.

It is ok though i will stay out of this thread

JIDOKA,

I understand your point and discussed it with the head guy at the lab!

And on top of that, came to an agreement on how to make your numbers valid! Doing exactly what needs to be done. That way the numbers will be valid.

And, I think I got it done at no additional cost!

And I am probably going to start making them do that for all my samples.

You want roses or something too?

Not sure why you are getting bent out of shape..

 

[slownickel]

I think I see where you are trying to go with this.

My point is not quite what you wanted to hear.

And again, you are correct as to run your calculations, you need specific density of your soil to figure out if you double or quadruple your numbers to make your calculation to dial it in.

I discussed this at great length with the head lab technician and the numbers really are not going to be exact exact until a 1 gram sample is measured with exactly the right amount of extractant. The number reported is not exact. This is step one. This is at the lab level.

That way the number will be perfect.

You should request a specific density test on top of that which says how many grams/volume of soil. You can easily do this at home. The lab will charge you $12 extra if you want them to do it.

And then of course you will have to double your amounts if the density is half that of a normal soil. I agree.

 

[plantingplants]

What is the one gram sample size based on if not soil density?

 

[slownickel]

My new grow... https://www.icmag.com/ic/showthread.php?t=335029

 

[slownickel]

Here is a library where you can get the Tiedjens book and lots of neat articles. If anyone has something that they thing should be in there that is not, please pm me to arrange to put it in there. Sort of like a library where we can discuss articles and stuff.

https://goo.gl/drwtMe