|
Calculate
Your Correction Factor
Click here to view chart.
Every farmer
knows lime is a cornerstone of high, efficient crop
yields. Keeping soil pH at 6.0 to 7.0 makes nutrients
and micronutrients more available, boosts herbicide
effectiveness, promotes populations of soil
microorganisms and improves soil structure.
That
impressive list of advantages makes it important to
ensure you maximize lime applications—and dial in pH. A
poor choice of product can waste money, and sloppy
application can create a patchwork pH pattern that can
take years to correct. Here’s how to make sure you get
your money’s worth when you apply lime.
Understanding Lime and Lab Recommendations
Agricultural
lime is ground-up limestone bedrock. It contains calcium
carbonate and magnesium carbonate, which neutralize
acidity in soil. Calcitic lime is mainly calcium
carbonate. Dolomitic lime contains both calcium
carbonate and magnesium carbonate. Soils become acidic
because of excessive hydrogen ions in the soil solution
and attached to soil particles. Calcium and magnesium
ions in lime displace some of the hydrogen ions—and take
their place on soil particles. Then the carbonates
neutralize the hydrogen ions.
Some soil
test laboratories make recommendations in terms of
calcium carbonate others make recommendations in tons of
lime—meaning tons of lime product with a typical CCE for
that state or region. If a lime product varies from that
standard, you must apply a correction factor to
determine how many tons you need to apply. “I recently
encountered a dealer who discovered he had been under
applying because he misinterpreted tons of CCE as tons
of lime,” says Farm Journal Field Agronomist Ken Ferrie.
Be sure you
and your dealer or lime applicator understand whether
your recommendation is for tons of CCE or tons of a
standard lime, as well as how to compare products.
Finally,
adjust your rate for incorporation depth. Most
recommendations are based on 9" moldboard plowing. If
you till shallower, reduce the application
proportionately. If you no-till, apply only one-third as
much (as if you were incorporating 3" deep).
What’s the
Best Lime Quality?
All lime
products are not equal in value because they are not
equal in neutralizing power. “There are no national or
regional standards for lime quality,” explains Randall
Warden, director of client services, A & L Great Lakes
Laboratories.
Even so,
lime quality determines how many tons to apply to
achieve the necessary pH change. The quality is
influenced by the calcium carbonate and magnesium
carbonate content, which is determined by laboratory
analysis and expressed as CCE. The CCE figure represents
the neutralizing power of the lime product compared with
pure calcium carbonate.
The
coarseness or fineness of the ground lime product also
impacts the quality. The fineness of the grind is
expressed as the percentage of particles passing through
several standardized sizes of mesh screens.
The finest
particles provide the quickest reaction with acidic
soil. Particles that pass a 60-mesh screen are effective
the first year. Bigger particles need more time. If you
have doubts about the grind, ask your crop consultant to
run a test just for you. “People understand the purity [CCE]
factor, but I think they often overlook fineness,”
Warden explains.
In most
cases, he notes, lime quarries grind their product for
customers other than farmers, such as road builders.
Those clients want a coarser product, and the fine
particles, of various sizes, which are left over are
what is sold to farmers for ag use.
One
exception is Stoneco of Milan, Mich. The company plans
to produce numerous grinds of lime for different uses,
including agriculture, at a new plant that is under
construction.
When you’re
buying lime, your supplier should be able to tell you
the CCE and the fineness of the grind. If they can’t at
first, ask them to find out.
What’s the
Best Buy?
Using CCE
and fineness, you can calculate a correction factor for
different lime products. (See page 31). The correction
factor lets you determine which one is the best buy.
The lower
the correction factor, the higher the quality of the
lime and the less required. Say one quarry is selling
higher-quality lime with a correction factor of 0.53 for
$8 per ton and another quarry is selling lower-quality
lime with a correction factor of 1.52 for $5 per ton.
(These prices do not include delivery and application
charges, which often equal the cost of the lime.)
If your
recommendation calls for 3 tons of lime per acre, you’ll
need to apply only 1.59 tons of the higher quality
material, costing $12.72 per acre. You’ll need to apply
4.56 tons of the cheaper material, costing $22.80 per
acre. So the cheaper lime is no bargain.
The Ideal
Grind for Lime
The
finest-ground lime is the hardest to spread, requiring
great attention to detail during calibration and
avoiding spreading on windy days. That’s why you need a
mixture of small and large particles (besides the fact
that small particles neutralize acidity immediately, and
larger particles continue neutralizing over several
years).
For ideal
spreadability, Warden suggests a product meeting the
follow criteria: 95% of particles passing an 8-mesh
sieve, 70% passing a 20-mesh sieve, 50% passing a
60-mesh sieve and 40% passing a 100-mesh sieve.
Getting
Uniform Coverage
Improved
hydraulics on today’s applicators allow wider spread
patterns, and rate controllers make delivery very
accurate. “But they make calibration even more important
than it was before,” says Lynn Dolan, Linco Equipment, a
New Leader dealer, El Paso, Ill.
Your
applicator owner’s manual will contain calibration
instructions, but here are a few general tips:
• Calibrate
for the type of lime you will be spreading. With a
coarser product, you can cover a wider swath—maybe 50'
compared with 30' or 35' with a finer grind. To check
the uniformity of your spread, set several large, flat
pans on the ground across the width of your swath and
make a pass over them.
• Remember
to take the density of the lime into account as you
calculate the flow rate, says Gary Cooper of The
Andersons Farm Center in Litchfield, Mich. It can vary
from about
70 lb. to about 90 lb. per cubic foot. Your supplier can
tell you the density or provide a density scale.
• Calibrate
your groundspeed radar, as well as your applicator.
• If you tow
an applicator behind your tractor, Dolan recommends
investing in a lightbar swather for guidance. “If a
field has been tilled across the rows, it’s very easy
for the driver of the applicator to switch from
following the old rows to following the tillage passes,”
he says.
• Consider
dealer support when you buy an applicator, Dolan
suggests. Ask if the company provides a service team to
calibrate your machine. If you buy a used spreader,
consider hiring a service team to calibrate it.
Fluid Lime
Suspensions
Fluid lime
contains lime recycled from municipal water systems and
industries—very fine particles suspended in water.
University of Illinois research indicates the rate of
reaction and neutralizing power are the same as for dry
lime of the same particle size. To get the product
applied evenly, there are some procedures you need to
keep in mind, Ferrie says. Your goal with any lime
product is to apply it as uniformly as you would paint
on a wall.
Buy from a
dealer with a sound reputation and who pays attention to
detail. A good dealer will mark each semi load with its
solid-lime content. That can vary from 14% to 25%,
depending on whether the material was drawn from the
top, middle or bottom of the lagoon. A skilled floater
operator will adjust his application rate to reflect the
solid content.
If the truck
hauls suspended lime a long distance, it may settle out
and need to be agitated, Ferrie says. A well-trained
operator will run the load through the applicator and
back onto the truck to mix it uniformly.
“After
application, you can tell if no one paid attention,”
Ferrie says. “The limed field will have a quilt-like
appearance, with dark and light spots.”
If you’re
offered a partially dried suspended lime product with a
semi-solid consistency—sometimes free from
municipalities—you’d be wise to reject it, Ferrie says.
“Usually, farmers try to apply it with a manure
spreader, and they wind up with clods of all sizes,” he
explains. “To be useable, the semi-solid product needs
to be dried and pulverized or pelletized.”
© 2004 AgWeb.com. All Rights Reserved. |
