Cec

[treegal1]

so here is the CEC thread, yes it is going to start off as a cut and paste..........

CEC, as reported by nearly all soil testing laboratories, is a calculated value that is an estimate of the soils ability to attract, retain, and exchange cation elements. It is reported in millequivalents per 100 grams of soil (meq/100g).

In order for a plant to absorb nutrients, the nutrients must be dissolved. When nutrients are dissolved, they are in a form called "ions". This simply means that they have electrical charges. As an example table salt is sodium chloride (NaCl), when it dissolves it becomes two ions; one of sodium (Na+) and one of chloride (Cl-). The small + and - signs with the Na and the Cl indicate the type of electrical charges associated with these ions. In this example, the sodium has a plus charge and is called a "cation". The chloride has a negative charge is called an "anion". Since, in soil chemistry "opposites attract" and "likes repel", nutrients in the ionic form can be attracted to any opposite charges present in soil.

Soil is made up of many components. A significant percentage of most soil is clay. Organic matter, while a small percentage of most soil is also important for several reasons. Both of these soil fractions have a large number of negative charges on their surface, thus they attract cation elements and contribute to a higher CEC. At the same time, they also repel anion nutrients ("like" charges).

Some important elements with a positive electrical charge in their plant-available form include potassium (K+), ammonium (NH4+), magnesium ( Mg++), calcium (Ca++), zinc (Zn+), manganese (Mn++), iron (Fe++), copper (Cu+) and hydrogen (H+). While hydrogen is not a nutrient, it affects the degree of acidity (pH) of the soil, so it is also important. Some other nutrients have a negative electrical charge in their plant-available form. These are called anions and include nitrate (NO3-), phosphate (H2PO4- and HPO4--), sulfate (SO4-), borate (BO3-), and molybdate (MoO4--). Phosphates are unique among the negatively charged anions, in that they are not mobile in the soil. This is because they are highly reactive, and nearly all of them will combine with other elements or compounds in the soil, other than clay and organic matter. The resulting compounds are not soluble, thus they precipitate out of soil solution. In this state, they are unavailable to plants, and form the phosphorus "reserve" in the soil.



Larger CEC values indicate that a soil has a greater capacity to hold cations. Therefore, it requires higher rates of fertilizer or lime to change a high CEC soil. When a high CEC soil has good test levels, it offers a large nutrient reserve. However, when it is poor, it can take a large amount of fertilizer or lime to correct that soil test. A high CEC soil requires a higher soil cation level, or soil test, to provide adequate crop nutrition. Low CEC soils hold fewer nutrients, and will likely be subject to leaching of mobile "anion" nutrients. These soils may benefit from split applications of several nutrients. The particular CEC of a soil is neither good nor bad, but knowing it is a valuable management tool.

The following, is data on how CEC is calculated at Spectrum Analytic.

Milli-equivalents (Meq.) of Selected Cations and Their Equivalent ppm

Cation
Atomic Weight
Valence
Milli-equivalents
Equivalent

ppm
Lbs/acre

H+
1
1
1
10
20

Ca++
40
2
20
200
400

Mg++
24
2
12
120
240

K+
39
1
39
390
780

NH4+
18
1
18
180
360

Al+++
27
3
9
90
180

Zn++
65
2
32.5
325
650

Mn++
55
2
27.5
275
550

Fe++
56
2
28
280
560

Cu++
64
2
32
320
640

Na+
23
1
23
230
460


Cation Exchange Capacity (C.E.C.) Calculation
On July 1, 2005, we began to report K, Ca, and Mg in Mehlich 3 ppm as well as our old method of reporting. When we did this we kept the same CEC calculations that we did on our old reports. Therefore, if you are getting a report that has Mehlich 3 ppm K, Ca and Mg reported in ppm you will need to use the following formulas to recalculate to our old converted reporting numbers. Below you will find the formulas.

Lbs K = (M3 K ppm � 0.84) � 2

Lbs Ca = (M3 Ca ppm � 0.75) � 2

Lbs Mg = (M3 Mg ppm � 0.88) � 2

METHOD 1: Use if a buffer pH (BpH) is available.

C.E.C. = (lb K � 780) + (lb Mg � 240) + (lb Ca � 400) + [12 � (7 - BpH)]*
* If buffer pH is 7.0 or greater, use a 0 value as the remainder...Example: (7.0 - 7.1) = 0

METHOD 2: Use if Buffer pH is not available.

C.E.C. = [(lb K � 780) + (lb Mg � 240) + (lb Ca � 400)] � Factor
Multiplication factors to use in method 2
If pH is
Use Factor*

7.3 or higher
1.00

7.2
1.05

7.1
1.10

7.0
1.15

6.9
1.17

6.8
1.20

6.7
1.22

6.6
1.25

6.5
1.28

6.4 or less
Use Method I


* The multiplication factor accounts for other cations

Percent Saturation
Both Percent Nutrient Saturation and Percent Base Saturation refer to a measurement, or estimate of the percent of the soil CEC that is occupied by a particular nutrient (nutrient saturation), or the sum of a group of nutrients (base saturation). This information gives us another tool to use in predicting the soils ability to provide adequate crop nutrients, and indicate needed changes in fertilizer or lime programs. A simplified example of percent saturation would be where a soil is capable of holding 100 cations and these 100 "exchange sites" are occupied by the following nutrients.

Nutrient
Nutrient Quantity (meq)
Nutrient Saturation
Base Saturation

Calcium (Ca++ )
67
67%
Sum of nutrient saturation of Ca, Mg, and K

67 + 15 + 3 = 85%

Magnesium (Mg++ )
15
15%

Potassium (K+ )
3
3%

Hydrogen (H+ )
12
12%


Others*
3
3%


Total
100
100%



*Includes Iron (Fe++), Manganese (Mn++), Copper (Cu++), Zinc (Zn++), Sodium (Na+), Aluminum (Al+++), and others.

The percent Nutrient Saturation is the saturation of the individual elements. The percent Base Saturation is the combined percent saturation of the three major cations that have a basic or alkaline reaction (K+, Ca++, and Mg++).

Since a soil test report is typically not measuring and reporting all of the cations that are in the soil, it is common for the sum of the measured cations to add up to less than 100%. Also, when the soil pH is above about pH 7.2, the sum of the cation saturation's may add up to more than 100%. This is because there is likely to be "free" Ca, Mg, and/or Na (unattached to the soil exchange complex) in the soil that is unavoidably extracted by the soil testing process.

Optimum Percent Saturation Ranges
There is some disagreement among agronomists about the value of using "optimum" percent saturation ranges of soil cation nutrients. One school of thought holds that it is very important that the soil contain a specific saturation, or ratio of saturations for each of the major cation nutrients (Ca, Mg, and K). Practitioners of this approach will make recommendations designed to adjust the soil to specific saturation levels. The opposing view is that there can be a wide range of saturation for each of these major cations, with no significant benefit to having particular saturation levels or ratio of saturation levels. The evidence suggests that the primary need is for an adequate amount of each nutrient, regardless of the resulting percent saturation, and that the desired saturation range can be quite broad. To the degree that there is an "ideal" percent saturation range or ratio of cation nutrients, it would be affected by several other factors such as any unique characteristics of a plant species, the intended use of the plants, the nature of the soil itself, and others. Our experience suggests that both the "pounds per acre" and the "percent saturation" philosophies have some merit in different situations, and that both should play a role in making recommendations.

Given that targets for percent saturation's can have some flexibility, the following table lists some suggested saturation ranges that would likely be considered acceptable by most agronomists.

Soil CEC
% K
% Ca
% Mg

0-5
4-6
50-70
10-20

6-10
3-5
50-70
8-20

11-15
3-4
50-70
8-20

16-20
2-4
50-70
8-20

21-25
2-4
50-70
8-20

26-30
1.5-3
50-70
5-20

30+
1.5-3
50-70
5-20


Keep in mind that when the soil CEC is between 0 and about 3, the percent saturation has less meaning agronomically. This is because the holding power of the soil is so low that even a deficient amount of a cation nutrient could result in a relatively high saturation. In those cases, the soil test is telling us that we should consider making multiple split applications of those cations needed in large amounts, because the soil in unable to retain any significant amount from a single application. One analogy that seems to illustrate how percent saturation works is comparing it to an irrigation system. The amount of the nutrient is similar to the amount of water applied in irrigation, while the percent saturation is similar to the water pressure of the irrigation system. The amount of water is most critical, but the water pressure plays an important role.

Soil pH and Buffer pH
Soil pH This is a measure of the soil acidity or alkalinity and is sometimes called the soil "water" pH. This is because it is a measure of the pH of the soil solution, which is considered the active pH that affects plant growth. Soil pH is the foundation of essentially all soil chemistry and nutrient reaction and should be the first consideration when evaluating a soil test. The total range of the pH scale is from 0 to 14. Values below the mid-point (pH 7.0) are acidic and those above pH 7.0 are alkaline. A soil pH of 7.0 is considered to be neutral. Most plants perform best in a soil that is slightly acid to neutral (pH 6.0 to 7.0). Some plants like blueberries require the soil to be more acid (pH 4.5 to 5.5), and others, like alfalfa will tolerate a slightly alkaline soil (pH 7.0-7.5).

The soil pH scale is logarithmic, meaning that each whole number is a factor of 10 larger or smaller than the ones next to it. For example if a soil has a pH of 6.5 and this pH is lowered to pH 5.5, the acid content of that soil is increased 10-fold. If the pH is lowered further to pH 4.5, the acid content becomes 100 times greater than at pH 6.5. The logarithmic nature of the pH scale means that small changes in a soil pH can have large effects on nutrient availability and plant growth.

Buffer pH (BpH) This is a value that is generated in the laboratory, it is not an existing feature of the soil. Laboratories perform this test in order to develop lime recommendations, and it actually has no other practical value.

In basic terms, the BpH is the resulting sample pH after the laboratory has added a liming material. In this test, the laboratory adds a chemical mixture called a buffering solution. This solution functions like extremely fast-acting lime. Each soil sample receives the same amount of buffering solution; therefore the resulting pH is different for each sample. To determine a lime recommendation, the laboratory looks at the difference between the original soil pH and the ending pH after the buffering solution has reacted with the soil. If the difference between the two pH measurements is large, it means that the soil pH is easily changed, and a low rate of lime will suffice. If the soil pH changes only a little after the buffering solution has reacted, it means that the soil pH is difficult to change and a larger lime addition is needed to reach the desired pH for the crop.

The reasons that a soil may require differing amounts of lime to change the soil pH relates to the soil CEC and the "reserve" acidity that is contained by the soil. Soil acidity is controlled by the amount of hydrogen (H+) and aluminum (Al+++) that is either contained in, or generated by the soil and soil components. Soils with a high CEC have a greater capacity to contain or generate these sources of acidity. Therefore, at a given soil pH, a soil with a higher CEC (thus a lower buffer pH) will normally require more lime to reach a given target pH than a soil with a lower CEC.


here is the most relevant cut and paste I can pull of in my state of repose..........

sorry Kiril i forgot to cut and paste the link, I think was from ANL

[ICT Bill]

That was a BIG paste
I thought JD was going to start the thread :) :) :)
great info except for all of the numbers, numbers make me dizzy :dizzy: :dizzy:


I am not going to comment on the basis of that information and who compiled it and then taught it for 40 years, only to create 1000's of 4 year degree hort students that could state fact

Not in the soil fact but fact from their 4 years in college, see I did not comment..... woo hoo

Good start, has anyone heard of the rhizosphere? Its close by

Dead soil in an experimental lab will probably do those things under conditions stated

Not my cup of tea :rolleyes:

I will agree about positive and negative forces, big mojo

[JDUtah]

sorry Kiril i forgot to cut and paste the link, I think was from ANL

http://www.spectrumanalytic.com/support/library/ff/CEC_BpH_and_percent_sat.htm

Bill,
Sorry, too busy right now.

[ICT Bill]

http://www.spectrumanalytic.com/support/library/ff/CEC_BpH_and_percent_sat.htm

Bill,
Sorry, too busy right now.

I know the feeling, just bust'n your chops

It is an interesting subject though you have to admit

[JDUtah]

I know the feeling, just bust'n your chops

It is an interesting subject though you have to admit

Indeed it is. :)

[Smallaxe]

I like this clear statement from the opening post. :)
Keep in mind that when the soil CEC is between 0 and about 3, the percent saturation has less meaning agronomically. This is because the holding power of the soil is so low that even a deficient amount of a cation nutrient could result in a relatively high saturation. In those cases, the soil test is telling us that we should consider making multiple split applications of those cations needed in large amounts, because the soil in unable to retain any significant amount from a single application.

This ending analogy was incomplete and will create confusion in many peoples' minds. This is a simple concept with indepth ramifications and is one thing universities are good for. But perhaps someone could clarify the analogy. :)

One analogy that seems to illustrate how percent saturation works is comparing it to an irrigation system. The amount of the nutrient is similar to the amount of water applied in irrigation, while the percent saturation is similar to the water pressure of the irrigation system. The amount of water is most critical, but the water pressure plays an important role.

[Kiril]

The relevant course notes if you want the details from the horses mouth .... Soil Chemistry (http://lawr.ucdavis.edu/classes/ssc102/)

[treegal1]

danka..............

[Kiril]

Good start, has anyone heard of the rhizosphere? Its close by

Bill you are just as bad as JD and his teaming microbes comment. FYI, there is more to plant nutrition and soil fertility than the rhizosphere. Perhaps we need to start a new thread on how plants acquire nutrients? :rolleyes:

[heritage]

Good Idea Kiril.

Mass flow and Diffusion.....Let the games begin :)

Pete

[Smallaxe]

... This ending analogy was incomplete and will create confusion in many peoples' minds. This is a simple concept with indepth ramifications and is one thing universities are good for. But perhaps someone could clarify the analogy. :)

One analogy that seems to illustrate how percent saturation works is comparing it to an irrigation system. The amount of the nutrient is similar to the amount of water applied in irrigation, while the percent saturation is similar to the water pressure of the irrigation system. The amount of water is most critical, but the water pressure plays an important role.

No analysis as to whether my comment about this second paragraph, is accurate. hmmm.

I will question myself: High pressure in an irrigation system delivers for water more quickly. [logical] but], We are NOT injecting it into the ground - afterall.

So what are we talking about here? Heavy saturation delivered quickly??

That was a great post, TG, I gotta say...
Smart , concise, and short on words. Worthy of discussion, since it is so critical to proper management of fert apps.
I know - discussion is boring on some subjects, but, I find it fascinating, so I discuss it with - ...me!!!
Wisconsinites are often seen, wandering about, in the snow, talking to themselves. So no problem.

We always say look to the soil, but what in the world are we looking at? Some see soil, some see dirt, a friend of mine in the first grade saw, snack. :)

[treegal1]

Wisconsinites are often seen, wandering about, in the snow, talking to themselves. So no problem.
its maybe better than us Floridians wandering around in the sun half naked talking to our trees......

i did not like the water analogy that was used, but decided to put it in there anyways just to spur discussion about this and/or even have a reson to talk it over with my self some.

I was going to write the analogy as bread and the amount of butter that a slice of bread can hold, the bigger the bread the more butter, does that mean you can eat the whole slice, if its to large? yes but maybe not all at once...... is this good or bad??? I guess it depends on the eat-er, and or his need for a drink with it...........

does this new analogy bring clarity, i don't know, most likely not as my wording and understanding may be way off, but lets keep talking to our self's and see....

[heritage]

its maybe better than us Floridians wandering around in the sun half naked talking to our trees......

i did not like the water analogy that was used, but decided to put it in there anyways just to spur discussion about this and/or even have a reson to talk it over with my self some.

I was going to write the analogy as bread and the amount of butter that a slice of bread can hold, the bigger the bread the more butter, does that mean you can eat the whole slice, if its to large? yes but maybe not all at once...... is this good or bad??? I guess it depends on the eat-er, and or his need for a drink with it...........

does this new analogy bring clarity, i don't know, most likely not as my wording and understanding may be way off, but lets keep talking to our self's and see....


Ahh Luxury Consumption....Hypertonic and Hypotonic Solutions.....Isotonic solutions.... :)

Are we talking about Plants or People........OR BOTH.

Yes Treegal 1, you started a good one.

Ready to learn some more...


Pete

[treegal1]

Ready to learn some more

is the pope catholic??? of course i am always learning, some may say forever a student...................

[Smallaxe]

its maybe better than us Floridians wandering around in the sun half naked talking to our trees......

i did not like the water analogy that was used, but decided to put it in there anyways just to spur discussion about this and/or even have a reson to talk it over with my self some.

I was going to write the analogy as bread and the amount of butter that a slice of bread can hold, the bigger the bread the more butter, does that mean you can eat the whole slice, if its to large? yes but maybe not all at once...... is this good or bad??? I guess it depends on the eat-er, and or his need for a drink with it...........

does this new analogy bring clarity, i don't know, most likely not as my wording and understanding may be way off, but lets keep talking to our self's and see....

Hahahahahaha, The biggest tourist attraction for 'Silent Sports', [Winter Activities] in Wiscinsin, IMO, is that - you don't have to see Wisconsinites, half naked.!! Just a row of pearly whites and sunglasses against a background of extraordinary beauty. :laugh:

I like the butter on toast analogy in that it clarifies that CEC is a sponge that soaks up so much - Then - no more. It sets me free to say, that:

I would like to see the soil structure that expands the CEC into the depths of 2-4 inches rather than - the top 1" plus - thatch layer.

Or am I still on the wrong trip?

[Kiril]

No analysis as to whether my comment about this second paragraph, is accurate. hmmm.

I will question myself: High pressure in an irrigation system delivers for water more quickly. [logical] but], We are NOT injecting it into the ground - afterall.

My analysis ... both of you should stay away from using sprinkler analogies.

[Kiril]

Or am I still on the wrong trip?

I support this statement. :)

[Smallaxe]

I support this statement. :)

Thanks Bud,,, that helps... :)

[treegal1]

My analysis ... both of you should stay away from using sprinkler analogies.yes I felt bad about it but in my defense it was a C/P so....


I am more interested in how the cec works with the tonicity of roots in trees and plants, mostly monocots....

more to learn

[bicmudpuppy]

I'll play. Using water as an analogy wasn't a bad idea. I think I understood the analogy, personally agree w/ Kiril (bad karma when that happens!!).

Consider saturation to be more of the pool the nutrients come from. CEC is the size of the distribution pipe. You could have a Pond with a million gallons of water, but if all you have is a 1" pipe to drain said pond with........................

Now, if your CEC is perfect, it would be like working with TG and having a six or eight inch trash pump with a ten cylinder diesel pump. For most situations somewhere in between is a good situation, and we still have to have a NEED for the water (nutrients) we are moving. All the water in the pond and the biggest pumps in the world will have zero value if we have no reason to use/move what we are moving.

[treegal1]

thank you mr water man, for fixing what a lab had to say, dude email them this thread and your wording of it, just maybe insert there Name or Albert Einstein..........

[Kiril]

thank you mr water man, for fixing what a lab had to say, dude email them this thread and your wording of it, just maybe insert there Name or Albert Einstein..........

Here is the analogy I came up with in another post .... not sprinkler related.


Imagine a playground (soil) with 20 kids (solution ions), 5 of which are bullies. This playground has 10 swings (exchange sites).

Everyone wants a swing, however the bullies always get them first (selectivity). So we have 10 swings with 10 kids (exchangeable ions) using them.

Then a bus pulls up with 20 more bullies (fertilizer with irrigation), so now the 5 swings that could be used by the other kids get taken by the bullies (activity, concentration, selectivity). As a result, some of the kids leave the playground (leaching).

Then a trailer pulls up with 40 portable swings (organic matter addition). Now there are enough swings to go around for everyone (increased buffering capacity).

The above is an over simplification of a complex process, and doesn't take into account solubility, pH dependent charge and reactions, differences between cation and anion exchange, solvation, chelation, sieve action, etc... but you get the gist it.

[heritage]

Here is the analogy I came up with in another post .... not sprinkler related.


Imagine a playground (soil) with 20 kids (solution ions), 5 of which are bullies. This playground has 10 swings (exchange sites).

Everyone wants a swing, however the bullies always get them first (selectivity). So we have 10 swings with 10 kids (exchangeable ions) using them.

Then a bus pulls up with 20 more bullies (fertilizer with irrigation), so now the 5 swings that could be used by the other kids get taken by the bullies (activity, concentration, selectivity). As a result, some of the kids leave the playground (leaching).

Then a trailer pulls up with 40 portable swings (organic matter addition). Now there are enough swings to go around for everyone (increased buffering capacity).

The above is an over simplification of a complex process, and doesn't take into account solubility, pH dependent charge and reactions, differences between cation and anion exchange, solvation, chelation, sieve action, etc... but you get the gist it.


So far this is the BEST analogy I have seen.

Nice one Kiril.

Pete

[ICT Bill]

Bill you are just as bad as JD and his teaming microbes comment. FYI, there is more to plant nutrition and soil fertility than the rhizosphere. Perhaps we need to start a new thread on how plants acquire nutrients? :rolleyes:

I know.... bad day. I'm over it

Great post Kiril :)

[JDUtah]

So now my question is, how does the OM provide better CEC? C sites directly? Through improved soil structure? Both? Other?

[Smallaxe]

So now my question is, how does the OM provide better CEC? C sites directly? Through improved soil structure? Both? Other?

Cation exchange sites are particles that are charged (-) and small enough for adsorbtion of the (+) mineral elements.
Sand is very poor for holding nutritive minerals. Clay and OM particles are usually the best, that a soil has to offer for expanding the CE Capacity of a soil.
Now we are learning that char is even better, because the surface area is so much greater.
[if this is error, someone let me know]

With Kiril's analogy, we can add a lot of minerals to a givin soil, however, the soil may not have the capacity to use the ferts, [CE Capacity, that is] So they may wash away b4 they find a home. Makes sense to me.

Clay without good soil structure will have a lot of sites , but:

My question is - What is happening with these sites [chemically] when the clay is physically compacted and greasy wet or baked dry?

[Smallaxe]

The one thing about this thread is that something was learned.
It was explained - why -

Compost does a soil good. :)

Now if LCOs could just start looking at their soils and determining if most of the NPK they are putting down will ever make it to the plant or not?

20# of grain meal per k, or, .75# of N per k.
It is still all about inputs rather than managing the soil.

[heritage]

The one thing about this thread is that something was learned.
It was explained - why -

Compost does a soil good. :)

Now if LCOs could just start looking at their soils and determining if most of the NPK they are putting down will ever make it to the plant or not?

20# of grain meal per k, or, .75# of N per k.
It is still all about inputs rather than managing the soil.

Enjoyed this thread as well :)

As for the Guys that choose to NOT add Compost on Low CEC soils/mediums, I wish there was a Polymer coated "Complete" NPKS Mineral Fert available, more cost effective than Osmacote, or the fert that came out a while back called "Once".


Pete

[Smallaxe]

Enjoyed this thread as well :)

As for the Guys that choose to NOT add Compost on Low CEC soils/mediums, I wish there was a Polymer coated "Complete" NPKS Mineral Fert available, more cost effective than Osmacote, or the fert that came out a while back called "Once".


Pete

These 'polymers'. Do they build CEC or do they have sites of their own?

[JDUtah]

Now for the 'how' does compost add CEC?

[Kiril]

These 'polymers'. Do they build CEC or do they have sites of their own?

I believe the polymers are just a "controlled release" coating, nothing more, nothing less.

Now for the 'how' does compost add CEC?

Are you serious?

[JDUtah]

Haha Kiril,

Sure OM provides Cation exchange sites. That's obvious. I was wondering if anyone explains the chemistry of it.

Also, does soil structure effect CEC? (I'm sure it does, but how)

Also, is there any value to "anion exchange sites"?

I enjoy lurking this thread and hope we can keep it going.

Edit: I just noticed your link on page one... I am reviewing it now.

[Kiril]

Sure OM provides Cation exchange sites. That's obvious. I was wondering if anyone explains the chemistry of it.

It is a pH dependent charge of surface O and OH groups.

Also, does soil structure effect CEC? (I'm sure it does, but how)

If you are sure it does, perhaps you would care to explain? While you are at it, make sure you address the difference between total and effective.

[JDUtah]

It is a pH dependent charge of surface O and OH groups.



If you are sure it does, perhaps you would care to explain? While you are at it, make sure you address the difference between total and effective.

Guessing... if the 'playground' is too crowded the ions can't find the open swings as easily. So-to speak. I have no idea about the total and effective... yet.

Still reading the chemistry stuff, I'm beginning to be sorry I asked. :laugh: Once again it is evident that soil chemistry is much more complex than chemical engineering principles used in manufacturing. :dizzy:

[Kiril]

Ask yourself how soil bulk density might affect something like pH.

[White Gardens]

I have a question.

What happens when.....

A.) Too much P and K are present in the soil and will never come down to acceptable levels without a major overhaul.

B.) The P.H. value is extremely Acidic and would take years to get it back to acceptable levels.

I've always understood that this relates to the Cation Exchange in soils, and how nutrients become bound up.

Someone correct me if I'm wrong.

[JDUtah]

Ask yourself how soil bulk density might affect something like pH.

hmmm.. :hammerhead:

Maybe I am showing my ignorance here, but I had no idea bulk density would affect pH.

But one step at a time, I think the higher the bulk density the higher the pH would get? Is that right?

[Kiril]

Maybe I am showing my ignorance here, but I had no idea bulk density would affect pH.

I'm not saying it does or doesn't. I want you to present a logical reason why it might or might not. Think of things that affect pH that might be related to soil bulk density.

[Kiril]

I have a question.

What happens when.....

A.) Too much P and K are present in the soil and will never come down to acceptable levels without a major overhaul.

B.) The P.H. value is extremely Acidic and would take years to get it back to acceptable levels.

I've always understood that this relates to the Cation Exchange in soils, and how nutrients become bound up.

Someone correct me if I'm wrong.

The first question you need to ask yourself is why either has occurred.

[JDUtah]

I'm not saying it does or doesn't. I want you to present a logical reason why it might or might not. Think of things that affect pH that might be related to soil bulk density.

Well time for a risk. Right now I can see this...

Soil particles have a negative charge and pull cations out if the solution. This leaves anions in solution which will bond to the H+ ions. This increases the concentration of OH- which would make it more alkaline.

The more dense the soil particles (increased bulk density) the higher the concentration of cations pulled out of solution which would make the soil solution more alkaline.

I could be way off but that was the reasoning behind my guess that an increase in bulk density could increase pH.

THEN, if bulk density does affect pH, it also affects the CEC of that soil because pH affects CEC, especially on organic matter.

[Kiril]

Try again .... think gas.

[JDUtah]

Oh! maybe...

The soils ability to 'breath' affects pH (think carbonates). If it can't breath it could become more acidic (maybe)?

Now if I understood the reading, the more acidic a soil is the less CEC (as far as OM is concerned)?

Close eyes, shoot shotgun.

[Kiril]

Oh! maybe...

The soils ability to 'breath' affects pH (think carbonates). If it can't breath it could become more acidic (maybe)?

Now if I understood the reading, the more acidic a soil is the less CEC (as far as OM is concerned)?

Close eyes, shoot shotgun.

Yes. Probably will not result in a change worth mentioning, but the contribution of carbonic acid to the solution pH due to increased CO2 may result in a minor decrease in pH dependent charges (primarily OM and some clays). Also consider potential influence of changes in NH3, N2O, NOx, CH4 between compacted and uncompacted soils.

[JDUtah]

I see. So different molecules are present in aerobic vs. anaerobic soils which affect pH and thus the CEC of organic matter (and some clay particles).

As far as what is worth mentioning... keep your soil aerobic via proper soil structure and irrigation to encourage the most Cation Exchange Sites. Good enough?

On that note... is this CEC/pH relationship what affects nutrient availability?

For example Manganese is more available at a pH lower than 7 because the CEC sites are not as likely to hold onto it?

[JDUtah]

Ok now the difference between total and effective CEC...

Total CEC is done with a solution pH of 7.0. Usually done with a buffer in the solution.

Effective CEC is the CEC when measured at the soil pH.

Because some (most?) Cation Exchange Sites are pH dependent, the effective CEC is more important to us (yes, no?)

Comparing total CEC to effective CEC can help us know what a pH adjustment might do to nutrient availability?

[White Gardens]

I see. So different molecules are present in aerobic vs. anaerobic soils which affect pH and thus the CEC of organic matter (and some clay particles).

As far as what is worth mentioning... keep your soil aerobic via proper soil structure and irrigation to encourage the most Cation Exchange Sites. Good enough?



My problem with irrigation is that most municipalities have a PH level of around 8, so, is it a double edge sword.

[heritage]

These 'polymers'. Do they build CEC or do they have sites of their own?

No they won't change CEC.

Where CEC is very low ie. sandy soil profiles, I feel UNTIL OM is added to such soil types, we should fertilize with Controlled release Elements ONLY.

Just my .2 cents.

Pete

[Smallaxe]

No they won't change CEC.

Where CEC is very low ie. sandy soil profiles, I feel UNTIL OM is added to such soil types, we should fertilize with Controlled release Elements ONLY.

Just my .2 cents.

Pete

The reason I ask about polymers, is because, a product called Liquid Gold. It contains 20,000 molecule weight polymers with + and - charges that supposedly works it way into the soil opening micropassages as it goes.

Whether it ever related to CEC I was never sure. Thanks for the reply.

[Kiril]

I see. So different molecules are present in aerobic vs. anaerobic soils which affect pH and thus the CEC of organic matter (and some clay particles).

More or less yes. Anything that affects soil pH can lead to a change in pH dependent charge. The extent of that change in a compacted and/or anaerobic soil may not even be enough to reasonably quantify. What you should take away from this exercise is factors which can affect soil pH may also affect soil CEC.

As far as what is worth mentioning... keep your soil aerobic via proper soil structure and irrigation to encourage the most Cation Exchange Sites. Good enough?

Good soil structure = house with solid foundation

On that note... is this CEC/pH relationship what affects nutrient availability?

Yes it can, but not only in how it relates to CEC.

For example Manganese is more available at a pH lower than 7 because the CEC sites are not as likely to hold onto it?

That is one possibility, simply put.

Because some (most?) Cation Exchange Sites are pH dependent, the effective CEC is more important to us (yes, no?)

For management decisions I would say yes.

Comparing total CEC to effective CEC can help us know what a pH adjustment might do to nutrient availability?

There is more going on here than simply CEC when pH changes. I prefer to look at CEC as a measure of overall soil fertility.

[Smallaxe]

...
Originally Posted by JDUtah
For example Manganese is more available at a pH lower than 7 because the CEC sites are not as likely to hold onto it?

That is one possibility, simply put. ....

I'm lost here.
What are we saying with the word 'available' in the question?

I'm thinking that - The Mg would be more 'available' to the plant - When it's connected to an Exchange site. Is that correct?

Next thought that comes to me is that once the new swings arrive you have more Mg without adding a Mg fertilzer.
So is JD refering to 'available' in the sense it is already in the soil and therefore 'available' under better conditions?

If my thinking is correct, we are "adding" fertilizer by improving conditions in the soil i.e. CE sites, pH, and such; without actually adding fertilizer.

[Kiril]

JD was talking about Mn (manganese) not Mg (magnesium). Easy to confuse the two.

If my thinking is correct, we are "adding" fertilizer by improving conditions in the soil i.e. CE sites, pH, and such; without actually adding fertilizer.

Ay .... the goal of the sustainable approach to soil management. But as has been said many times, chasing pH is not a contest you will win. Manage the soil best you can to promote better buffering capacity and use plants that can handle the native conditions of the soil.

[Smallaxe]

JD was talking about Mn (manganese) not Mg (magnesium). Easy to confuse the two.



Ay .... the goal of the sustainable approach to soil management. But as has been said many times, chasing pH is not a contest you will win. Manage the soil best you can to promote better buffering capacity and use plants that can handle the native conditions of the soil.

Good - 'Mn', thanks.

I have been trying to read into the articles buffering capacity. How do you think it works.

Rodale's group said years ago that more OM would 'buffer' the effects of pH, whether high or low.
Question is - How does that work?

[Kiril]

Question is - How does that work?

The most simple answer is increased CEC.

[heritage]

The reason I ask about polymers, is because, a product called Liquid Gold. It contains 20,000 molecule weight polymers with + and - charges that supposedly works it way into the soil opening micropassages as it goes.

Whether it ever related to CEC I was never sure. Thanks for the reply.

Liquid Gold from CPS? Ammonium Sulfate I think.

Ammonical N is a +Cation
Sulfate is an -Anion

AmSo4 does move through the Soil profile, but the Polymers added IDK.

I was referring to the Polymer Coating on an NPKS product I would like to see used on Low CEC soil/medium wher Compost /OM is not added.

Perhaps a "Compost Coated NPKS Pellet" to be broadcast?

Time will tell I guess.

Pete

[JDUtah]

OK, so I think I am getting the general idea. Thanks Kiril. :) I like to understand what is going on but don't worry, I am not looking for a silver bullet. The more I understand about it all, the more customized I can be. Thanks again.

Smallaxe,
When I asked about the Mn, I was just testing the idea that at higher pH (on pH dependent exchange sites) the ions might not be released into the solution. Remember, the grass only gets the nutrient ions that are in a solution.

You could think of it like this...
The pH dependent 'swings' buckle in the ions and if the solution pH is too high they will not let the 'rider' free. They think to themselves "it is not the environment for these ions to go into, I will keep them on this swing." Thus the nutrient is not available to the plant.

For instance we have alkaline soils here that have enough iron, but the iron is not usually available. It is told to us that a lowering of the soil pH can release this iron. I suspect (need to read more) that this is partly because the iron cations (ferric and ferrous) can bind too strongly to the soil particles in alkaline soil. They just don't get off the swing.

Wow, so I just re-read a little more out of that plant physiology book (http://www.sinauer.com/detail.php?id=8567) (prolly the 6th time I have read this part) and I think I might understand a part of why adding OM and CEC sites helps buffer soil pH.

Page 86 gives a general explanation of biology and soil pH over time. It mentions that H ions can "displace K+, Mg2+, CA2+ and Mn2+ from the cation exchange complex in a soil. Leaching then may remove these ions from the upper soil layers, leaving a more acid soil. By contrast, the weathering of rock in arid regions (Utah) releases K+, Mg2+, CA2+ and Mn2+ to the soil, but because of the low rainfall, these ions do not leach from the upper soil layers, and the soil remains alkaline."

OK, a few check understanding questions for Kiril...

I know there is more going on than just this (like Phosphorus bonds (http://msucares.com/crops/soils/phosphorus.html)) but I wonder... is one reason you suggest adding OM to buffer pH because...

Just like leaching the cations away can promote soil acidity, binding them to soil particles also removes them from the soil solution thus encouraging more free H ions (and a more buffered soil solution)?

And on the flip side... in regions that have a lot of leach potential, binding the ions to the OM will discourage them form leaching thus keeping them in the soil and encouraging them to tie up more H ions in the soil solution?

But I am thinking this is a more temporary fix for my type of soils? Proper leaching might be the best way to manage this (after the SOM buffer)?

Hmmm, that prolly has a lot to do with the water you use to irrigate. You know someday when I know better what is going on I will get into a good irrigation study. It seems pretty central to an organic approach...

And yes, don't chase the pH ghost. ;)

[JDUtah]

Perhaps a "Compost Coated NPKS Pellet" to be broadcast?

Barry's screemin' green (http://www.techterraorganics.com/turf-org.php) is just that. Not pelletized though?

[Smallaxe]

The most simple answer is increased CEC.

So compost being closer to neutral, providing accessable nutrients in the form of CE sites, is now part of the soil profile simply by being a percentage of the overall makeup.
Sounds logical to me.

[Smallaxe]

Liquid Gold from CPS? Ammonium Sulfate I think.

Ammonical N is a +Cation
Sulfate is an -Anion

AmSo4 does move through the Soil profile, but the Polymers added IDK.

I was referring to the Polymer Coating on an NPKS product I would like to see used on Low CEC soil/medium wher Compost /OM is not added.

Perhaps a "Compost Coated NPKS Pellet" to be broadcast?

Time will tell I guess.

Pete

Made like this I guess. Evidently 'polymer' has a lot of meanings.

*(polymaleic anhydride terpolymer and maleic anhydride sulfonated copolymer)*

This is one description:

*...similar to the electrolytes found in sports drinks, but much, much more complicated. These polymers (very complicated) are HUGE--over 20,000 combined molecular weight. Most of these substances are hydrophilic--they LOVE water. One of the polymers is strongly hydrophobic (runs away from water). Due to these polymers high molecular weight, they're very, very stable. *

[Smallaxe]

... Wow, so I just re-read a little more out of that plant physiology book (http://www.sinauer.com/detail.php?id=8567) (prolly the 6th time I have read this part) and I think I might understand a part of why adding OM and CEC sites helps buffer soil pH.

Page 86 gives a general explanation of biology and soil pH over time. It mentions that H ions can "displace K+, Mg2+, CA2+ and Mn2+ from the cation exchange complex in a soil. Leaching then may remove these ions from the upper soil layers, leaving a more acid soil. By contrast, the weathering of rock in arid regions (Utah) releases K+, Mg2+, CA2+ and Mn2+ to the soil, but because of the low rainfall, these ions do not leach from the upper soil layers, and the soil remains alkaline." ...

The type of buffering that Rodale was refering to indicated that it did not matter what the pH was; with enough compost the plant could perform well anyways.
Perhaps it has more to do with increasing the ability of the rhizosphere to create its own micro-environment.

A question on your pg. 86 reference: Does compost bring in more H ions to provide for the displacement?

Thanks for the response. It appears the research will continue to generate more questions than answers for a while, but it sure feels good when that ratio turns around. :)

[Kiril]

@JD,

There is more to nutrient availability than just how it relates to CEC. You must also consider precipitation of solids (i.e. insoluble) as is the case with iron at high pH. Also consider how anaerobic conditions might affect nutrient availability.

With respect to buffering of nutrients .... good place to start is by understanding the difference between active (in solution) and reserve (exchangeable) as is applies to CEC.

As far as H+ displacement of ions ... I would only expect this to occur at high concentrations of H and with respect to some pH dependent sites.

I refer you to the lyotropic series.

http://www.pals.iastate.edu/agron154/Agron_154/Unit_17/terms.htm#72

[JDUtah]

The type of buffering that Rodale was refering to indicated that it did not matter what the pH was; with enough compost the plant could perform well anyways.
Perhaps it has more to do with increasing the ability of the rhizosphere to create its own micro-environment.

A question on your pg. 86 reference: Does compost bring in more H ions to provide for the displacement?

Thanks for the response. It appears the research will continue to generate more questions than answers for a while, but it sure feels good when that ratio turns around. :)

Indeed more questions than answers, but that is learning for you.

About the "compost" adding H ions, it says...

"Major factors that lower soil pH are the decomposition of organic matter and the amount of rainfall. Carbon dioxide is produced as a result of the decomposition of organic material... This reaction releases hydrogen ions, lowering the pH of the soil. Microbial decomposition of organic material also produces ammonia and hydrogen sulfide that can be oxidized in the soil to form the strong acids nitric acid (HNO3) and sulfuric acid (H2SO4)."

When I read this I kind of wonder if a more raw OM would be better than compost (for this application). If I understand correctly the compost has already been greatly decomposed and the humates therein are fairly stable. Thus less CO2 = less H ions released.

Sorry if this is getting off topic.

[JDUtah]

@JD,

There is more to nutrient availability than just how it relates to CEC. You must also consider precipitation of solids (i.e. insoluble) as is the case with iron at high pH. Also consider how anaerobic conditions might affect nutrient availability.

With respect to buffering of nutrients .... good place to start is by understanding the difference between active (in solution) and reserve (exchangeable) as is applies to CEC.

As far as H+ displacement of ions ... I would only expect this to occur at high concentrations of H and with respect to some pH dependent sites.

I refer you to the lyotropic series.

http://www.pals.iastate.edu/agron154/Agron_154/Unit_17/terms.htm#72

So does the lyotropic series represent all the cations related to CEC? Iron isn't even in there. Dough! :laugh:

Question, when the iron becomes insoluble is it still considered a mineral (in mineral form)?

I'll study more on active, reserve, and CEC...

[treegal1]

its like using meals or grains.........

[Smallaxe]

Indeed more questions than answers, but that is learning for you.

About the "compost" adding H ions, it says...

"Major factors that lower soil pH are the decomposition of organic matter and the amount of rainfall. Carbon dioxide is produced as a result of the decomposition of organic material... This reaction releases hydrogen ions, lowering the pH of the soil. Microbial decomposition of organic material also produces ammonia and hydrogen sulfide that can be oxidized in the soil to form the strong acids nitric acid (HNO3) and sulfuric acid (H2SO4)."

When I read this I kind of wonder if a more raw OM would be better than compost (for this application). If I understand correctly the compost has already been greatly decomposed and the humates therein are fairly stable. Thus less CO2 = less H ions released.

Sorry if this is getting off topic.

I think you are right about more raw materials, than compost for reducing alkaline soils.

On the farm - the annual plowing under the previous crop debris is considered to cause the pH to move in the acid side of the spectrum.
Wonder if that is for the same reason??

[Kiril]

Indeed more questions than answers, but that is learning for you.

About the "compost" adding H ions, it says...

"Major factors that lower soil pH are the decomposition of organic matter and the amount of rainfall. Carbon dioxide is produced as a result of the decomposition of organic material... This reaction releases hydrogen ions, lowering the pH of the soil. Microbial decomposition of organic material also produces ammonia and hydrogen sulfide that can be oxidized in the soil to form the strong acids nitric acid (HNO3) and sulfuric acid (H2SO4)."

Yes .... this is where I was leading you earlier in the thread.

When I read this I kind of wonder if a more raw OM would be better than compost (for this application). If I understand correctly the compost has already been greatly decomposed and the humates therein are fairly stable. Thus less CO2 = less H ions released.

I don't think I would equate compost with humin. In some cases raw OM may be the ticket, it really depends on what you are trying to achieve. What you want to achieve in a typical landscape soil is balanced nutrient turnover, raw OM may not give you that, at least with respect to N.

[JDUtah]

Yes .... this is where I was leading you earlier in the thread.

Hind site is 20/20 :laugh:

I don't think I would equate compost with humin. In some cases raw OM may be the ticket, it really depends on what you are trying to achieve. What you want to achieve in a typical landscape soil is balanced nutrient turnover, raw OM may not give you that, at least with respect to N.

I see

[heritage]

Barry's screemin' green (http://www.techterraorganics.com/turf-org.php) is just that. Not pelletized though?

Thanks JD.

Pete

[heritage]

Made like this I guess. Evidently 'polymer' has a lot of meanings.

*(polymaleic anhydride terpolymer and maleic anhydride sulfonated copolymer)*

This is one description:

*...similar to the electrolytes found in sports drinks, but much, much more complicated. These polymers (very complicated) are HUGE--over 20,000 combined molecular weight. Most of these substances are hydrophilic--they LOVE water. One of the polymers is strongly hydrophobic (runs away from water). Due to these polymers high molecular weight, they're very, very stable. *

I will ponder that comparison.

Having been an Athlete, I understand about Glucose Polomers, being a Longer Chain Carbon with a lower Glycemic index. Mixed too strong and it's Hypertonic and will actually pull water from the cells/gut and slow gastric emptying, causing bloating.

More diluted was best as it is Isotonic and can leave the gut quickly to go into cells and muscle. Much better than short chain Carbon (glucose/sucrose)

So how do the Polomers work in soil as they are Hydrophobic, and draw water to them??

Is this like too high a salt (index) that will pull water away from roots, to the salt of higher concentration?

Is this comparable with the Hyper-tonic solution??

Will this have and effect on CEC in the soil?

Pete

[phasthound]

Barry's screemin' green (http://www.techterraorganics.com/turf-org.php) is just that. Not pelletized though?

The reason why Nutrients PLUS chose that name is because it gives you the NPK.......PLUS the organic matter.
We've been able to demonstrate the success of this bridge product both commercially in the field and more recently with studies comparing it to a popular 28-5-12. Same results, less NPK input. Better price. Other studies and clients report lower disease problems.

Screamin' Green is not an extruded pellet, it is a true granular giving a uniform, non dusty application. There are 5 sources of N that provide an even, long term green without flush growth.

[Smallaxe]

I will ponder that comparison. ...

Is this comparable with the Hyper-tonic solution?? ...

Pete

Gosh!!! I hope not!!!

This is hydrophilic as well as hydrophobic.
I think there are 2 different polymers based on the ad.