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Pioneer Water Testing Laboratory
Spring
Agri
ADDRESSING THE NEEDS OF AGRICULTURAL PRODUCERS AND
PLANTING THE SEEDS FOR A SECURE FUTURE.
focus
A MESSAGE FROM THE PRESIDENT
George W. Mitchell, President/Agronomist
Welcome to our newsletter, Pioneer Water Testing
Laboratory’s, “Agri Focus”. Our main objective
with publication is to keep you informed about
recent developments in our industry and shine the
spotlight on laboratory equipment, software,
personnel and quality control.
Our newsletter will cover a wide range of topics;
ones that will explore new and exciting ideas both
here in our laboratory and throughout our
industry. Education is the key to our future! Here
at PWTL, we pride ourselves on the fact that we
are always trying to learn more! We continually
strive
to
make
consistent
laboratory
improvements, educate ourselves to stay on top of
the latest technological advances and research,
and are always looking to ensure the utmost
quality control for you, our valued customers.
We are seeing unprecedented change in our
industry. Milk price is at an all time low,
fertilizer commodities are in unfamiliar
territory, and feed commodity prices hit an all
time high not long ago. I welcome this as a new
beginning. I welcome the challenge. Everyone
here at PWTL is working hard to streamline
processes and to find efficient ways to use
technology. We will partner with you to listen
and understand your needs! PWTL is on your
side as your business’ copes with these
uncertain economic times.
As always, our goal at PWTL is to provide the
best
analytical
results
possible
while
continuously being mindful of your needs and
treating you, our customer, with the highest
regard.
Thank you for your patronage,
George
EQUIPMENT SPOTLIGHT
Near Infrared Reflectance Spectroscopy (NIR)
Jeff Foster, Owner/CFO
Near Infrared Reflectance spectroscopy (NIR) is a
complicated analytical method for quickly determining
nutrient structure. Utilizing spectral properties of the forage,
multiple nutrients are determined simultaneously. The NIR
was first utilized for forage and feed analysis in the late
1970's. Its popularity has blossomed over the last 25 years to
make it our most popular service. NIR is recognized by the
Association of Official Analytical Chemists (AOAC) as an
official method of analysis.
We continued to enhance our computer hardware and
software which has contributed to progressive improvement
of the technology. The NIR is calibration dependent.
Historically, our calibrations were developed for common
sample types by analyzing hundreds to thousands of samples.
The chemical information contained in these samples is
correlated to spectral properties and a calibration is born.
As the need for additional elements such as Fat
and Ash were asked for by our customers, we
were able to expand our calibrations. As the
need for Starch and Sugar was apparent, we
worked with the University of West Virginia to
expand our calibrations. We are also able to
expand calibrations through being a member of
the NIRS Consortium.
As you know, we have an extensive Wet
Chemistry Laboratory here at Pioneer Water
Testing Laboratory. If you prefer Wet
Chemistry results or the NIR is unable to read a
sample and tells us to run the sample in our
Wet Chemistry Lab, we are able to do so. We
take pride in providing you with the best
analytical results.
Agri Focus
Spring
Page 2
Soil pH, Buffer pH and Principles of Determining Soil Lime Requirement
Using the Mehlich Buffer
Tim Hoerner
Agronomist/Feed & Forage Support Manager
Maintaining a neutral or near
neutral soil pH through the
addition
of
finely
ground
limestone to the soil provides
most agronomic and horticultural
crops
with
an
optimum
environment in which to grow.
The roots of these crops can
perform their functions best when
the soil pH is optimum. Not only
is the movement of essential
nutrients into the roots impacted
by the soil pH but so is the release
of these essential nutrients from
other soil constituents such as clay
and organic matter.
What is Soil pH?
From our laboratory perspective,
Soil pH is a measure of the acidcausing elements present in a
mixture of water and soil. This
mixture of soil and water is
referred to as the soil solution.
The soil solution contains not only
the acid-causing elements but also
a multitude of dissolved elements,
many of which are essential for
plant growth. On a soil test report
this value is listed under the
heading “Soil pH”. Soil pH is not
a measure of the total soil acidity.
More information on this later in
“What is Total Soil Acidity”.
What is the source of Soil
Acidity?
The elements that produce most of
the soil acidity are hydrogen and
aluminum. Hydrogen is the main
source
of
soil
acidity
in
agricultural soils. Aluminum does
not contribute significantly to the
measured soil acidity until the soil
pH drops well below pH 6.
Hydrogen and Aluminum must be
in their oxidized or ionic form in
order to produce acidity. This
means the hydrogen or aluminum
had to be a part of another
substance prior to breaking away
and entering the soil solution.
Where do Hydrogen and
Aluminum Ions come from?
Hydrogen, the primary source of
soil
acidity,
comes
from
numerous sources. These can
include the breakdown of crop,
manure, and other organic
residues by soil organisms, the
addition of certain fertilizer
materials, the conversion of
ammonia-nitrogen to nitratenitrogen, and the loss through
leaching of basic chemical
compounds. Aluminum is part of
the particles that make up soil,
especially clay. Its contribution
toward soil acidy is not
significant until a very large pool
of hydrogen ions accumulate in
the soil and depress the soil pH
below 5.5.
When aluminum
reacts with water at these low
pH’s, some of the hydrogen in
the water is released, adding
even more to the soil acidity.
Is all of the Soil Acidity
located in the Soil Solution?
Only a portion of this aciditycausing hydrogen can be present
in the soil solution at one time.
The remaining hydrogen ions
become attached to soil particles
and fragments of organic matter.
These points of attachment are
called exchange sites. Additional
exchange sites become available
to hydrogen ions when nutrients
such as calcium, potassium, and
magnesium move into the soil
solution from the soil particles to
replace nutrients removed by the
plant or through loss by water
moving through the soil.
What is Total Soil Acidity?
Total Soil Acidity is the sum of
the hydrogen ions in the soil
solution plus the exchangeable
hydrogen ions on the exchange
sites.
To neutralize a soil
requires knowing more than just
the Soil pH. It is necessary to
know how much acidity is stored on
soil exchange sites. On a soil test
report, the Total Soil Acidity is listed
under “Acidity” and expressed as
milliequivalents of acidity per 100
grams of soil or simply meq/100g.
Think of Soil pH as the air pressure in
a tire and Total Soil Acidity being the
size of the tire. A truck tire and a
bicycle tire can have the same
pressure (pH) but the truck tire (clay
soil) holds a lot more air (acidity)
than a bicycle tire (sandy soil).
How do we eliminate Total Soil
Acidity?
By applying limestone to the soil in
sufficient quantities and mixing it
throughout the root zone, all of the
soil acidity is eliminated or more
correctly, neutralized.
What happens in the Soil when
Limestone is applied?
Limestone is composed of calcium
carbonate, a chemical that slowly
dissolves in water and soil solution.
When limestone dissolves in the soil
solution, it separates or “dissociates”
into two separate ions: calcium, which
is positively charged and carbonate,
which is negatively charged. Through
a chemical reaction, it is the
carbonate ion, not the calcium that
reacts with the hydrogen ion in the
soil solution to form a new
compound. The hydrogen in this new
compound is bound and is no longer
available to contribute to the acidity
of the soil solution. This effectively
neutralizes the acidity of the soil
solution.
What about the Exchangeable
Hydrogen ions?
This is where the calcium from the
limestone plays a large role. As the
hydrogen ions in the soil solution
become bound to the carbonate ions
from the limestone, more hydrogen
ions are released into the soil solution
from exchange sites on the solid soil
particles - the reserve acidity.
Article continued on page 3…
Agri Focus
These hydrogen ions also react with
the carbonate ion and no longer
contribute to the soil acidity. While
this is occurring, the calcium ions are
attaching to the exchange sites
formerly occupied by the hydrogen
ions. The huge number of calcium
ions in the soil solution help push
more of the hydrogen ions from the
exchange
sites
through
a
phenomenon called mass flow.
Within about 6 months, all of the
finely ground limestone will have
dissolved into the soil solution,
replacing all of the acid-causing
hydrogen ions on the soil exchange
sites with its calcium, and will have
reacted with and effectively removed
the hydrogen ions from the soil
solution, resulting in a neutral pH
soil.
How is the Soil Limestone
Requirement Determined?
Researchers and people with a lot of
time on their hands can determine
the soil limestone requirement by
splitting a large soil sample into
many smaller subsamples, adding
increasing amounts of ground
limestone to each moist subsample,
incubating all of these subsamples in
a warm oven for several weeks, and
then measuring each one’s pH with a
pH meter to see which amount of
limestone raised the soil pH to the
desired level. Need your limestone
recommendation a tad faster than
that? Next is a very rapid procedure
that is calibrated to perform as well
as this time-intensive method!
The Soil-Buffer Method
As seen above, soil and limestone
take weeks or months to react. That
is the reason we don’t just add
limestone to soil samples in the
laboratory and immediately measure
the pH. The reading would keep
changing until all of the limestone
was dissolved and reacted with the
soil acidity. Instead, soil is added to
a “buffer solution” and the rapid
change in the buffer’s pH that occurs
in minutes indicates how much
acidity is present in the soil and
therefore how much limestone is
required.
Spring
A chemical buffer is a substance
that resists change of some sort.
A pH buffer is a solution that
resists changes to its pH even as
foreign materials are added to it.
By creating a pH buffer that
responds quickly in a way that
resembles soil when limestone is
added to it, a laboratory test can
accurately predict, in short order,
the amount of limestone that will
be needed to change the pH of a
soil. Just as limestone is added
to soil to raise its pH over time,
soil is added to the buffer to see
how much the buffer’s pH drops
as a result of any acidity in the
soil. The lower the buffer pH, the
greater was the amount of acidity
in the soil. If the buffer pH does
not change at all, then the soil
contains no acidity.
Seems
simple, right?
Not really.
Chemicals can be combined in
millions of ways to create
millions of pH buffers that react
in different ways. Which one is
right for our soil testing needs?
Finding the “Right” Soil
Buffer
The “right” soil buffer to use
depends on the nature and
characteristics of the soil to be
tested. Some buffers are great
indicators of large amounts of
soil acidity in clay-based soils but
fail to respond with clarity to the
small amounts of acidity in sandy
soils. A buffer that responds well
to the low acidity in sandy soils
may underestimate the acidity in
more acid soils.
By understanding the various
processes that create acidity in
soils, specific chemicals that
react to each process can be
added to the soil buffer solution.
Buffers used in soil testing
include the Woodruff buffer,
SMP buffer, Adams-Evans buffer,
Mehlich buffer, and the MooreSikora buffer. Each one works
well
under
specific
soil
conditions. For decades the SMP
buffer has been used on silt loam
and clay loam soils in the eastern
United States with good success.
Page 3
Why switch to another Soil
Buffer?
The SMP buffer contains two
chemicals
that
require
special
handling and disposal procedures. In
an effort to remove chemicals such as
these from routine laboratory use and
the waste stream, other common soil
buffers were evaluated to replace the
SMP buffer.
The Mehlich buffer mentioned above
is very similar to the SMP buffer in
the way it responds to soil acidity but
it too contained an environmentally
unfriendly chemical. Unlike the SMP
buffer, a substitute chemical was
found to replace the problem
chemical in the Mehlich buffer that
does not change its buffer properties.
Limestone recommendations based
on the SMP and Mehlich buffers are
almost identical for a given soil
sample.
Additional benefits to using the
Mehlich Buffer
The Mehlich buffer responds better
than the SMP buffer to low soil acidity
levels that require one ton of
limestone or less to neutralize, such as
those from frequently limed clay soils
and sandy soils with few exchange
sites. Because of the difficulty and
expense of applying small amounts of
limestone to fields, we do not provide
limestone recommendations of less
than one ton per acre.
What may change on the Soil
Test Report?
Using the Mehlich buffer, we are able
to report Acidity values less than 2.0
milliequivalents (2.0 meq/100g soil)
on our soil analysis report. Low
Acidity values were not reported using
the previous SMP buffer even though
up to one ton of limestone may have
been recommended.
Using the Mehlich buffer, the Cation
Exchange Capacity or CEC may be
slightly higher on soils with low
acidity than when the SMP buffer was
used on those same soils. This is due
to the reporting of low acidity values
when using the Mehlich buffer. This
CEC is likely a better representation
of the soils exchange capacity.
Continued on page 4…
Agri Focus
Spring
Page 4
A slight increase in the CEC will cause a
corresponding small decrease in the reported
percent base saturation of potassium,
magnesium, and calcium. Although minimal,
these decreased saturations may result in
slightly more potassium and magnesium being
recommended. The reason for this is that our
baseline soil levels for potassium and
magnesium are based on specific base
saturation levels for these two nutrients. If the
percentage of the CEC made up of potassium
and magnesium drops (which happens when
more acidity is added to the CEC total),
additional potassium and magnesium will be
recommended to meet the desired baseline
levels.
Does anyone else use the Mehlich Buffer?
In addition to the soil laboratory at Pioneer
Water Testing Laboratory, other laboratories
using the Mehlich buffer include Penn State
University, Virginia Tech, Dairy One, University
of Maine, and North Carolina Department of
Agriculture.
USING PLANT ANALYSIS AS A TOOL
TO MONITOR NUTRITIONAL STATUS
Lisa Dreibelbis, Agronomy Service Manager
Plant growth and productivity in agricultural growing
systems is almost always below its maximum
potential. Factors influencing this statement involve
genetics, environment and nutrition.
Genetics are controlled thru the use of cultivars, the
environment can be managed to a degree by using
practices such as: irrigation, fertigation, plasticulture
etc.. Nutritional deficiencies/toxicities that are
limiting growth can be diagnosed by utilizing plant
analysis. Plant analysis (also referred to as leaf
analysis) determines the elemental content of a
particular plant part for 14 essential plant nutrients.
The approach to using plant analysis can be viewed
reactively or proactively. The reactive approach is
when a plant analysis is sent to the lab to verify visual
deficiency/toxicity symptoms. Unfortunately, when
this approach is used it is often too late; plant growth
and yield goal are already detrimentally affected.
Over the past several years plant analysis for most
growers has switched to the proactive philosophy.
The proactive grower will use a sequence of plant
analysis to track and log the nutritional status of the
plant throughout the growing season. This weekly
monitoring of nutritional status allows the farmer to
“correct on the grow”. The results of the plant analysis
findings are used to determine if soil fertility level and
applied fertilizers are high enough to meet the crops
requirements. This monitoring allows for adjustments
and supplements to be added to the fertigation process
resulting in stronger plants and increased yields.
Spring is just around the corner and it’s time to be
prepared for the coming growing season. Test your soil
to determine soil health and fertility prior to planting. If
you are applying manure have it analyzed also, with the
high cost of fertilizer these two simple tests could put
money in your wallet. Finally choose your approach to
plant tissue testing, will it be reactive or proactive?
Agri Focus
Spring
Page 5
ECONOMY WATCH: The Agriculture Industry
Greg Zimmerman, Feed and Forage Service Manager
Everywhere we turn these days it is hard to
avoid the news of companies announcing layoffs,
plant closures, and/or financial losses. The
economy has taken a turn for the worse and the
future of most industries is cloudy. Uncertainty
and fear has gripped its hold on the world.
Despite the recent news, the agricultural related fields have remained steady as the demand for
food does not decline with the slide of the stock markets. We can all be thankful to be weathering
the storm in a relatively safe environment.
That is not to say that agriculture has not seen any effects: commodity prices have fallen; milk prices have fallen;
farms have had to scale back in size; but there is a strategy for industry to ride the waves and come out on the other
side with minimal damage. Blessings can be found if one looks hard enough: with the plummeting oil prices, the
demand for ethanol fuel has fell along with it and has led to closures of ethanol facilities leading to a surplus of corn
on the market, thereby bringing feed prices down that just last spring were of so much of a concern. There are
reasons for hope.
Here at Agri Analysis, we are also looking to the future with the attitude of being right there with you through these
hard economic times; working with you to provide the testing needs that fit into your financial budget. Also at this
time, we are still working to improve our methods and expand our testing capabilities. We appreciate any input
that you, our customers, have on what you would like to see available.
If you are just finding out about us and would like to know more, or a current customer looking to improve or refine
your testing, please contact us today. I’m sure we have a package available that suits your needs and budget.
AGRI ANALYSIS INC.
a division of
PIONEER WATER TESTING COMPANY, INC.
ANALYZE TWO
FEED AND FORAGE SAMPLES
&
TEST THE 3RD SAMPLE FREE!
**Complimentary test must be of equal or lesser value.
** Must include coupon with samples to be tested to receive this offer.
Agri Analysis, Inc. — 280 Newport Road — P.O. Box 483 — Leola, PA 17540
Phone: 717-656-9326 — Website: www.agrianalysis.com
**Limit 1 per customer