permaculture

["Lawrence F. London, Jr." <lflj@bellsouth.net>]

-------- Original Message --------
Subject: Re: [SANET-MG] Soil phosphate (was organic vrs conventional) - 
chemistry and extraction methods
Date: Thu, 11 Nov 2010 14:24:57 -0500
From: Elaine Ingham <soilfoodweb@AOL.COM>
To: SANET-MG@LISTS.IFAS.UFL.EDU

In response to Michael Astera's comments -

I have spent quite a bit of time talking to lab people all over the world about their methods.  For example, talk to the 
Director of the Environmental Analysis Lab at Southern Cross University if you think your experience is the only one 
that counts in the world.  Examine the scientific literature, and discover there are probably more than 500 different 
extracting methods and agents for extracting phosphate, or phosphorus, or other nutrients, from soil.



 Look at the values obtained using currently used extracting agents, for example, Bray 1, Mehlick 1, Reams, Universal, 
simple water extraction methods (I could go on, and list, oh, maybe ten more methods by if I refreshed my memory by 
looking at different soil chemistry lab reports.  Give me a day in the scientific literature, and I could name a couple 
hundred more methods).

The values using just those few "common" methods range from 0.5 to 150 ppm, using the SAME SOIL, taken at the same time, 
and handled exactly the same, up until the different extracting agents were used.  The actual value obtained depended on 
which extraction method was used, but ALL those methods are used to measure "soluble PO4", or soluble nutrients.

And quite often, different values will be obtained with each method, depending on whether you dilute the sample first, 
or if you dilute following extraction.

So, which is truth?

Which is the correct value?

If I was a chemical salesperson, which method of extraction would I recommend, if I'm making money by convincing people 
by looking at a soil chemistry report that they need more PO4?

--------------

And those are just soluble methods.  Methods to assess "exchangeable" nutrients are just as ...... well, variable.  But 
that's why people always say "pick a lab and use that one lab".  Except if you really understand the problem, you can 
use different labs.  Just make sure you understand what they really do at that lab, and what part of the soluble set of 
nutrients that particular extraction method actually tells you about.

Oh wait, no one can actually tell you what part of the actual soluble pool is being extracted, by any method you choose 
to use.  Change temperature, change moisture, change soil type, and .......... hum, what part of the soluble pool are 
you actually extracting with any of these methods?  It changes.  So, what does it really mean?

There may be five or six standards methods some individuals ARE AWARE OF, but that does not change the fact that many, 
many more methods are "on the books", and used to some extent some place on the planet.  Please recall that not 
everywhere on this planet do people have high tech labs to send samples for analysis.  In fact, it is probably more the 
exception that soils samples are assessed with advanced technological equipment than are assessed using low tech methods.

In the comments from M Astera, he pointed out the difference between soluble and total, and then said to me that perhaps 
that is the reason for the confusion about what soluble really is.  Confusion on my part?  I think Michael is confused.

Soluble means dissolved in water.  Total levels usually include soluble PLUS what is not in solution.  So Michael's 
comments in fact point out exactly what I was saying.  There's huge difference between soluble and and not-soluble, or 
not-plant available pools.   Clearly defining these different pools is necessary, and then doing the necessary things to 
make sure nutrients are cycling from one to the other normally is absolutely necessary.

Note that most of the data on a soil chemistry report is just soluble information.  Almost never is the total 
concentration of any nutrient reported on a soil chemistry report.  If a grower asks, they can get exchangeable nutrient 
information.... i.e., base saturation of Ca, Mg, K, and Na, but given all the nutrients in the soil, why pick those 
four?  What is with chemistry labs starting to include Al, or H in that limited list?

Ok, I'm being rhetorical here, because I know why.  But I bet 80% of the growers using soil chemistry labs have no clue 
what that is all about.  Growers trust their agronomist, who is at least helping them grow reasonable amounts of plant 
material, so the operation stays alive.  But do the soil agronomists know why Albrecht values can no longer be obtained 
from many soil chemistry reports?

------

Soluble values tell you about what the plant MIGHT be able to take up at the instant of time the assessment was made. 
Will the plant actually take up those nutrients that are in solution?  Maybe, maybe not.  No way to tell.

I have seen soil chemistry data where there was massive amounts of soluble iron (or PO4, or SO4, or NO3) in the soil. 
But the PLANT TISSUE was lacking iron (or PO4, or S, or N, etc).  The plant was dying from a lack of nutrition.  So, 
what use is doing soluble soil chemistry?  It was actually misleading to the grower.

I have seen soil chemistry reports where soluble phosphate levels (Reams) were 0.01 ppm.  Exchangeable phosphate levels 
(Mehlick 3) were 0.1 ppm. and yet the plant had normal or in a couple cases, excess phosphorus in its tissue.  But the 
grower was told to pour on the PO4 fertilizer, regardless of the fact that the plants did not need any additional PO4. 
Ah, organic matter levels were 20%, and there was good biology present, so the soil pool of PO4 was constantly 
maintained.  At low values, but constantly maintained.  Since replenishment was constant, although at low levels on a 
second by second basis, the plant was perfectly happy.   We don't need outrageous amounts of leachable (=soluble) 
nutrients in our soils, we just need to constantly replenish those soluble, or leachable, nutrients.  But we don't want 
high concentrations of those soluble nutrients at ANY time.

What really determines what plants take up?  What is the minimum threshold value of soluble nutrients in soil that 
plants require?

There's plenty of data to show that the conventional chemical attitude about 
soil chemistry tests is completely wrong.

Please note I did NOT say that soil chemistry tests were useless.  Don't extrapolate incorrectly and go off into some 
wild, outrageous insane response.

Those of you reading this can see I do quite a bit of work with soil chemistry tests.  I just object when they are used 
to justify pouring on very expensive soil amendments that in most cases, you don't need.

-------------------

Most commonly, in commercial soil chemistry labs, the samples, when they arrive, are dried and then sieved.  The rocks, 
the large chunky material, including larger organic materials remaining on the sieve are thrown away.  Once sieved, then 
ok, the organic matter remaining is not thrown out, but that initial soil sieving step is standard practice.  People 
might want to go to their chemistry lab, and actually see what is happening, so they can have a better idea how to 
interpret the results they get from the chem lab.

-------------------

In my previous e-mail, I did NOT discuss in any way transmutation of chemicals.  There was not even the slightest 
suggestion that N can be converted to S, or P into Ca, or any such silliness.

Making some kind of crazy leap that I was talking about transmutation of chemicals in soil, when I was talking about 
what biology does in converting forms of, for example, N into other forms of N, or is beyond belief.

It is organisms that convert nitrogen from N2 gas, into amino acids and proteins, from proteins into ammonium, and then 
to nitrite, and then to nitrate, or if things go anaerobic, into ammonia, or nitrous oxide, and subsequently into N2 gas 
again.  In the conversion from plant-not-available forms of Ca, or P, or S, or B, or whatever, it is the biology in the 
soil that does the transformation from the rock forms of these elements into the biologically useful forms of these 
elements.

All these changes in forms of the nutrient are done BY ORGANISMS.  Chemical cycling is insignificant in the face of 
biologically performed nutrient cycling.

But exit from your INTERPRETATION that I'm talking about changing one element 
into another element.

---------------------

Let's go back to what I was actually talking about.

Consider the real world.  If soils from the most productive ecosystems on this planet are assessed, the levels of 
soluble nutrients in those soils are typically extremely low.

Get a conventional soil chemistry test done on old growth forest soil.  Tell your agronomist the sample is from your 
lettuce field, and watch your agronomist go ballistic.  The fertilizer recommendation will likely break your bank.

But.......

How can those towering trees, the secondary understory, the shrub layer, and the herbaceous layer in that forest be 
alive?  According to fertilizer salesmen, there aren't enough nutrients in the soluble pool to provide lettuce with 
enough nutrients to grow, so how can trees, shrubs and herbs get enough nutrients to stay alive?  But they are alive, 
and growing, and produce more biomass on an annual basis than any agricultural field.

Where do those nutrients come from?  Where do those plants, in systems that NEVER, EVER get inorganic fertilizer 
amendments, but are the most productive of anything on the planet on an annual basis, get their nutrients from?  Don't 
be silly and say that none of the plant material is removed each year from an old growth forest.  Export from these 
systems is documentable, and significant.

So, how can natural systems remain productive for centuries, without addition of nutrients from outside the system?  In 
the real world, it is nutrient cycling by microorganisms that do the conversion from not-plant available forms of 
nutrients, into plant available forms.

I am NOT invoking transmutation.  Please, don't be ridiculous.

How does "Mother Nature" supply nutrients to plants?  No one is out there, applying inorganic fertilizer.  For the 
history of the PLANET, no one was applying inorganic fertilizers until about 60, maybe 65 years ago.  How did plants 
manage to get nutrients before that?   Plants have been around, what, a BILLION years?

How do systems manage to maintain constant levels of nutrients for plants to 
take up?

It ISN'T the size of the pool that is important, it is the RATE OF REPLENISHMENT.  If a small, or large, concentration 
is constantly replenished, then there is no need to be adding more.

What does the replenishment in soil?

Soil life.  The FULL food web, not just bacteria.  Bacteria by themselves will ultimately tie up all the nutrients and 
result in harm to the plants.  So, it has to be more than just bacteria....... the FULL foodweb.

------------------------

The soluble pool of nutrients IN A FERTILIZER may only be 2 percent of the total amount of that nutrient present.  But 
based on measuring P in solution (i.e., soluble), an assumption was made that there is 16% more fertilizer P that can 
become soluble (i.e., available) sometime in the future.

So these are two different pools.  The form of P that is in the exchangeable, not in solution, pool, is quite different 
from the form of P that is in solution.  It is important when PO4 is complexed with carbon, or calcium, or some other 
cation which is not in solution, versus when PO4 is complexed in water.

HOW do nutrients get converted from one form into the other?   From soluble into exchangeable, or total pools?  Or from 
total into plant available?

Yep, there are three different pools that are discussed quite often in the soil chemistry world, depending on which 
sort-of "school" of soil chemistry you follow.

I think of the soluble pool (dissolved in water), the exchangeable pool (tied up on surfaces but excluding organism 
surfaces, because extracting agents can't access those surfaces), and the total pool, which is EVERYTHING of that type 
of nutrient that is in the soil.

To convert from one form to another (not changing the element, but rather changing what the element is complexed with) 
in the chemical world, you have to have a fertilizer production plant (most of us don't have one of those in our soils, 
and in fact they didn't exist before, oh, 1940?  So, how did these changes in form happen before that?)  or you have to 
add concentrated acids to convert the not-soluble forms into soluble forms.

But no one is out in nature adding acid on the soil to make those not-available nutrients become available.  What is the 
process that nature uses to move elements from the complexed-in-rock-form to the complexed-with-organic-matter-form, to 
free in solution?
How does it happen in the real world?

Microorganisms. Acids?  Bases?  Or enzymes? Which is more efficient and less destructive?  Thank you, but I'll take 
enzymes every time.   Stop destroying soil by pouring acid, or base on it.  Get some enzymes going.... um, which 
requires biology.  Remember, if you just put out enzymes, you can't afford an on-going conversion.  Instead, get 
organisms going, which GROW, as long as you feed them by having plants in the system and increasing OM.  Any of you 
growers don't grow plants?  Ok, so get those organisms back into the soil and get them working for you.

Look up the work by D.C. Coleman, P. Hendrixs, or really, anyone in the Soil Ecology Society.  It is the full food web 
that is required.  there's a meeting of the society coming up this next spring.  Find out how nature does it.  If we 
ever want to be sustainable, we have to pay attention to the sustainable way of doing this.

----------------------------------

Now, on to the depleted soil concept.

Where is most of the P, S, Ca, or any other nutrient in a soil?

In the sand, silt, clay and rocks, right?  Or if you have a good organic soil, most of the N, P, K, Ca, S, etc will be 
in the organic matter.  Please note, before someone goes ballistic on me again, that I did not say that N was highest in 
the sand, silt, clay and rocks.  In organic matter, yes.  But you have to have that BIOLOGICAL process to convert 
atmospheric N into plant available forms.  No one could possibly imagine that the chemical fixation methods of making 
nitrate are sustainable.  But, back to the point.

Has any farmer, any grower, ever run out of sand, silt and / or clay in their 
soils?

It is a silly question, isn't it?

Of course, soil is MADE OF the basic mineral part of soil, i.e., sand, silt or clay.  Every year, the bedrock below your 
soil breaks down a little more, and provides new sand, silt and / or clay, based on what the bed rock is.  So, constant 
replenishment of the mineral forms of nutrients.

So, when will your soil "run out of" any nutrient you want to talk about?  When you run out of sand, silt or clay.  When 
bedrock is no longer there.  What is the probability that you will run out of the mineral forms of nutrient in your 
soil?  Will any of these things get used up in your life time?  Your great-great grand child's life?  Hasn't happened 
yet, so I think we are safe on this.  Stop worrying about do you have enough P in your soil.  It is there already.

How could you ever run out?

But then why do our plants show nutrient limitations?

What have we destroyed, or at least, severely harmed, in most soils managed 
by people?

Um, the things that perform the Processes of changing the rock P into plant available P.   The organisms that FIX 
nitrogen.  The organisms that convert CaPO4 into plant available Ca, or plant available PO4.  Or lime into plant 
available Ca.  Or..... well the list goes on forever.

Humans destroy soil life without ever realizing it is there working for us.  Too much tillage (hear those voices 
screaming as the organisms are crushed?), use of toxic levels of sulfur, or vinegar, or copper, or any pesticide (as 
beneficial organisms die from contact with these things, imagine their agony), compaction (most pathogens require 
reduced oxygen to to be able to out-compete the beneficials), and so the life we need to do nutrient cycling is slowly, 
or in some cases, not so slowly, destroyed.

Disturbances kill the organisms that perform the PROCESSES of making plant not-available forms into plant available 
forms.  And then our plant production systems become dependent on toxic chemicals to continue to grow plants.

I'm not arguing that the toxic chemical approach can't result in stuff we can eat.  Sure it can.  But look at the toll 
it takes on human health.  On the planet's health.  Where is the clean water we need to have?

ANY inorganic fertilizer will kill some part of the beneficial sets of soil life, given a concentration more than 100 
pounds per acre.  And people are putting out TONS of lime (yes, it is salt), tons of gypsum (that's a salt too), 400 
pounds or more of urea, and so on and so forth.  ALL pesticides kill organisms far beyond the range of the target 
organisms.  What is the effect on soil life of adding these toxic materials?

Please, don't throw studies at me that use human-health measurement methods to say toxic chemicals don't harm soil 
organisms.  Plate count methods, or growth on limited nutrient media in limited conditions in the lab, might be ok for 
assessing certain human pathogens, but are absolutely ridiculous for assessing life in the soil.  There's a few million 
species of bacteria and fungi (well, actually probably more like billions) that are NOT human pathogens, and actually 
suppress pathogens, but which DO NOT grow on microbiological media (i.e., plate counts).  So, don't make me laugh by 
quoting studies that use plate count methods to try to claim "these toxic chemicals don't kill beneficial life in soil". 
 Talk about chemical sales people trying to pull the wool over the public's eyes!

So, why not test your soil before you add anything to the soil, and then again, say 1 to 2 weeks after that application. 
 The soil actually has to be moist enough that the organisms are active and growing, so the toxic chemical will have an 
effect.

I had a chemical rep send in totally dry soil (less than 1% moisture, early August from the Great Basin of the US) 
before lime, or a pesticide, was applied, and then two weeks later, without rainfall, without water of any kind being 
applied, send in another sample.  There was no change in close-to-zero levels of life present before and after 
amendments were added.   He then proclaimed far and wide, see, these pesticides don't harm soil life.  Well, if you 
never apply water to your soil, then, salts or pesticides won't kill anything, including the target pest.  Good luck 
growing your plant, however.

So what did the pesticide salesman actually prove?  His pesticide didn't kill the disease fungi in that soil, but to 
conclude that a toxic chemical doesn't harm beneficial organisms?  Completely inappropriate.  Do testing in real 
conditions, not in a way that skews the results, as in the cases of salesmen wanting to claim that their toxic chemicals 
don' t harm soil life.

Buyer beware.

Or, get a microscope, and start looking at what is happening to the organisms in your own soil, to the nutrient cycling 
soil life when any material you want to add is actually added.

--------------

So, what has been done in BOTH conventional ag, and in organic ag in many (but not all) cases.  Human management so very 
often destroys the life we are dependent on to do things in a sustainable manner.

How can these organisms be put back?

Make good aerobic compost.  Aerobic, because when the normal diversity of beneficial, AEROBIC life is present, pathogens 
will be out-competed.

But people who have taken compost, with E. coli present in high numbers....

Wait.  It isn't compost if there's a boatload of E. coli present.  Something was VERY WRONG in the composting process if 
E. coli is detectable in high numbers after the thermal phase, or after worms have done their job.

That material cannot have the diversity of organisms needed to prevent pathogen growth.  Don't use that stuff, because 
it is not possible to get the benefits that a healthy food web should give you, if the composting process grew 
pathogens, instead of good guys.

Tricky?  No, not at all.  Easy to assess.

Nutrient cycling requires bacteria, fungi, protozoa, and benefcial nematodes to be present in minimum amounts and in 
proper balances in order to maintain constantly replenished soluble nutrient pools.

If one of more of those organism groups are lacking in your soil, then get the sulfur, copper and toxic chemicals out, 
because you are going to have disease, pest and nutrient limitations to plant growth that will require the toxics.  Not 
sustainable, but at least you will get a crop.

But, can't we change our ways, so we are sustainable?

Nature manages to grow massive amounts of plant material without using any toxic chemcial additions.  Just because 
humans don't yet understand how nature does everything, just means we haven't paid attention.

Do I know everything?  I am humbled all the time, by nature, by what I don't know.  There are parts of this nutrient 
cycling system I still don't understand.  But the answers are out there.

We just have to stop killing life in soil, especially the beneficial organisms in soil.  We need to pay attention to 
what those organisms are doing.

Instead of trying to dismiss them as being un-important.



Elaine R. Ingham
President, Soil Foodweb Inc.




-----Original Message-----
From: m_astera <michael.astera@GMAIL.COM>
To: SANET-MG <SANET-MG@LISTS.IFAS.UFL.EDU>; Elaine Ingham 
<soilfoodweb@AOL.COM>
Sent: Wed, Nov 10, 2010 9:17 pm
Subject: Re: Soil phosphate (was organic vrs conventional) - chemistry and 
extraction methods

I don't claim to be an expert on soil microorganisms but I do know a
bit about soils and chemistry.
There are five or six recognized extractants and methods used to
measure phosphate in soil, not five hundred. I know of no labs that
remove organic matter before grinding the sample to be tested.  As a
matter of fact I frequently see test reports done on highly organic soil
including compost and soilless potting mixes.  A test can also be
done by dissolving a sample of organic matter in nitric acid.  In all
cases, modern labs use ICP/MS (inductively coupled plasma/mass
spectrometer) technology to read the total amount of mineral, P or
other, in the extracted solution or the dissolved material.
The choice of extractant method is often a matter of philosophy, some
agronomists believing that plant roots can only produce a mild
carbonic acid, others wishing to know the maximum amount of P that
might be potentially available.

Fertilizer labels in the US are only allowed to list water-soluble
amounts of nutrients.  A bag of soft rock phosphate reads 0-2-0,
meaning it has 2% water soluble P2O5, but the actual total P2O5
equivalent is usually 18-20%.  Perhaps that is the source of the
confusion about what "soluble" means?  A strongly acid extractant
like the Mehlich 3 at pH 2.5 will solubilize most of the P that would be
potentially available under any conceivable agricultural conditions. If a
strongly acid extraction shows very low levels of P, then there are low
levels of P in that soil, regardless of what soil fungi may be present.
Biology does not make minerals that are not present, unless we
hypothesize transmutation of elements.
Various methods can be used to make available even the last tiny
dregs of P from a worn-out or depleted soil: inoculation with bacteria
and fungi, Biodynamic preps, paramagnetic rock, or various
biostimulants.  All of these can pull a decent crop out of a P depleted
soil, but doing so will only deplete the soil further.  None of them will
make P.

I have documented this phenomenon in Venezuela where
biostimulants have pulled some impressive crops out of abused and
depleted soils.  But the next soil test tells the story:  now there really
IS nothing left. To denigrate the value of a soil's exchange capacity 
indicates
that one does not understand its function.  Exchange capacity is a
measure of the soil's ability to hold charged particles, e.g. the mineral
ions that feed both the soil life and the plants. Without exchange
capacity, any soluble fertility elements in the soil would be washed
away with the first good rainfall or irrigation.  Ancient aged clays like
those in Amazon valley soils have almost no exchange capacity,
hence no ability to hold nutrients.  Adding biochar to such soils
restores exchange capacity and allows these ancient soils to hold
onto nutrients once again, making agriculture possible beyond the
slash and burn stage or the need to reapply soluble chemical
fertilizers constantly.  Without exchange capacity, a soil is little more
than a medium to hold the plant upright.

Michael Astera
http://soilminerals.com