xt78sf2m7h0v https://exploreuk.uky.edu/dips/xt78sf2m7h0v/data/mets.xml   Kentucky Agricultural Experiment Station.  journals kaes_circulars_004_619 English Lexington : The Service, 1913-1958. Contact the Special Collections Research Center for information regarding rights and use of this collection. Kentucky Agricultural Experiment Station Circular (Kentucky Agricultural Experiment Station) n. 619 text Circular (Kentucky Agricultural Experiment Station) n. 619  2014 true xt78sf2m7h0v section xt78sf2m7h0v ®%     @
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COOPERATIVE EXTENSION SERVICE
AGRICULTURE AND HOME ECONOMICS

 CONTENTS
Page
SOIL TESTING ........................................................................ 4
SOIL TESTING SERVICE IN KENTUCKY ...................... 5
COLLECTING SOIL SAMPLES ............................................ 6
When To Collect Samples ............................................ 7 A
Dividing the Field .......................................................... 7
Sampling Tools .............................................................. 8
Collecting Soil Cores ...................................................... 8
Hanclling the Sample ........................................,........... 9 ‘
THE SOIL TEST REPORT FORM ...................................... 9
LIMING ANI) FERTILIZING \\’HEN NO SOIL
TESTS ARE MADE ............................................................ IO
USING TIVIE LIME ANI) FERTILIZER RECOM- ,
MENDATION GUIDE ...................................................... IO
Al)_]USTING LIME AND FERTILIZER
RECOMMENDATIONS ......,............................................. I2
Mannre ............................................................................ I2
Tobacco Stalks and Stems .............................................. I2
Irleavy Nitrogen Applications ...................................... I2
Protluction Potential ol the Land ................................ I2 ,
Pliospliorus and Potassium Releasing Potential ........ I3
Correcting Exclmngeable Aciclity ................................ I7
I.IME ANI) FERTILIZER RECOMMENDATION
R.·\TES ......................................,.....................,...I.............,... I9 "
For Grain Crops ........,..................................................... I9
For Tobacco .....,.............................................................. 20
For Hay and Pasture Seeclings ..........,........................... 2l
For Legume-Grass or Grass Annual Toptlressing
(1*20;) .......................................................................... 22
For Lcgtnne-Grass or Grass Annual Topclressing
(K:O) ................................,....,..........,........................... 23
Nitrogen II`Ol)(Il`€SSIlIg—I,CgllI'lI€S and Grass .............. 24
BORON RECOMMENI),-\TION .........,................................ 24 I
(LR.\SS SEEI) PRODUCTION ()N ESTABLISI-IED SOI) 2·l
(ZON\'ERSlON FACTORS .......................,............................ 25
I<`ER>l`lI.IZER ANI) LIME APPLICATIONS ..................., 26
Time ol Application ...................................................... 26
Placcinent ........................................................................ 26

 Lime and Fertilizer
   
Recommendation Guide ‘
y Department of Agronomy _
College of Agriculture
University of Kentucky
The lime and fertilizer recommendations in this guide are based
on the results of soil samples tested in laboratories under the super-
vision of the Kentucky Agricultural Experiment Station. These
recommendations for Kentucky are arrived at by testing the soil,
applying various rates of plant nutrients, and measuring crop
response to each rate. The nutrient rate that gives the highest
economic crop response over a period of years is the basis for the
recommended amounts.
The lime and fertilizer recommendations listed in this guide
should not be applied to soil test results from laboratories that
use extracting chemicals, or other procedures that differ from those
used in Kentucky Experiment Station controlled laboratories.
A number of different extractants and procedures are being used
' to appraise the chemical status of soils. Soil testing laboratories
select their own extractants and establish their own methods and
procedures. The differences among laboratories in the extractants
used and the procedures followed often cause variations in the
reports of chemical properties being tested.
Variations in methods and procedures may include the ratio of ·
soil to extractant and/or the time of exposing the soil to the
extractant. The variations in extractants used may include different
extractants or the same extractant in different concentrations. Any
one of these variations or a combination of them will result in
different values being reported from one laboratory to another.
Farmers and others should not be alarmed when different lab-
oratories report different chemical values on the same soil. I-low-
ever, if the recommended rate of lime and fertilizer applications
is greatly different, this is cause for concern. The values of the
chemical properties reported should be of little concern if there
is sufficient information on the soil tests, soil treatments, and plant
responses available to determine the best lime and fertilizer treat-
3

 ment from the results of a particular soil testing procedure. If
correlations between soil tests and application rates have been
made, then lime and fertilizer recommendations from different
laboratories that use different soil testing procedures should be
approximately the same, providing the same soil type and yield
goals are involved. Therefore, lime and fertilizer recommendations
developed from research on soils that differ greatly from Kentucky
soil types should not be used for Kentucky soils. V
The lime and fertilizer recommendations in this circular are
based on the assumption that ammendments will be applied on
deep, well-drained soils of high production potential. The amounts
recommended should be adjusted downard as the production
potential of the land drops to medium or lower for the crop being `
grown. Likewise the recommended amounts should be adjusted
downard if the farmer’s yield goals are less than the production
potential of the land. How to determine when to make such adjust- _
ments is discussed more fully on pages I2 through 18 of this circular.
SOIL TESTING
Soil test results and a knowledge of past treatment and cropping
history provide the best information available for determining
quickly the lime and fertilizer needs of the land for a particular
crop or cropping sequence. But to be reliable, soil test results must i
come from a competent laboratory and be made on a soil sample
that adequately represents the chemical properties of the field or
area in question.
The results of a soil test are a measure of the chemical properties
of a soil at the time the test was made. Establishing lime and
fertilizer treatments on the basis of these results includes considera-
tion of the soil type ansl past treatment. For instance, some soils
have the capability of releasing potassium and phosphorus through-
out a growing season that may not be indicated by soil test results.
(See pages I2 through 18.) Furthermore, lime applied during the
previous three years probably has not reached its peak of effec-
tiveness.
\Vhen soil test results are properly interpreted, the amounts of
a nutrient or nutrients needed to provide a balance and an adequate
supply, and the amount of lime needed to adjust soil acidity to the
desired level, can be established for a particular crop or cropping
sequence.
4

 In the competitive business of farming the highest increment of
economic crop production often determines the margin of profit.
As farmers strive for such production, soil testing becomes more
important. Failure to invest a very few dollars in lime or plant
nutrients that are needed, or spending a very few dollars that are
V not needed, can turn potential profit into a break-even or a loss. -
SOIL TESTING SERVICE IN KENTUCKY
The soil testing services now available in Kentucky consist of
county laboratories and a central laboratory at the University of
‘ Kentucky in Lexington. The county laboratories conduct the fol-
lowing routine tests:
1. pH (water suspension).
- 2. Extractable phosphorus (0.15 N sulfuric acid).
3. Extractable potassium (0.15 N sulfuric acid).
The central laboratory conducts the following tests:
1. pH (water suspension).
2. Lime requirement (see pages 17-18 for interpretation).
3. Extractable phosphorus, Bray’s No. 1 extractant.
4. Extractable potassium, 1 N Neutral ammonium acetate.
The charge per sample is $1.00 for tests through 4.
5. Extractable magnesium, 1 N neutral ammonium acetate.
6. Extractable calcium, 1 N neutral ammonium acetate.
The charge per sample is $1.50 for tests 1 through 6.
7. Spurway’s test for greenhouse soils ($2.00/sample).
8. Organic matter content ($1.00/sample). '
In addition to those nutrients now being tested for, there are
other nutrient elements which are required for optimum plant
growth. Some of these elements are known or suspected of being
problems in Kentucky soils. Accordingly, research is being con-
ducted on procedures and correlations to increase the number of
elements for which soils can be tested. As plant response informa-
tion becomes available to aid in interpreting new tests, they will be
offered as additional services in the central laboratory.
Crop response to fertilizer and lime in studies conducted by the
staff of the University of Kentucky Agricultural Experiment
Station furnish the basis for interpreting the soil test results as
given on pages 19 through 24. When using soil tests to make
5

 decisions on fertilizer practices, it is always important to regard the
"lbs/A" shown by the soil test merely as an index and not as
actual pounds per acre of readily available nutrients in the soil.
The results of soil tests by most laboratories are reported as “lbs/A"
of extmctable nutrients which are related to, but not identical to,
available nutrients. Therefore, it is important to use the test level
of high, medium, or low to arrive at a "fertilizer decision." .
COLLECTING SOIL SAMPLES
(For more detailed information see Kentucky Leaflet 139, "H0w _
To Take Good Soil Samples") i
The results reported for a given soil test and the ensuing lime
and fertilizer recommendation applies only to that portion of soil
sample that was submitted for testing. If the soil sample does not _
adequately represent the soil of the entire held or area to be
treated, the test results will not reflect the chemical properties of
the field, and thus the recommendations when followed may not
supply the nutrients needed for economic crop production. Poorly
collected soil samples set the stage for inaccurate treatment recom-
mendations that can lead to disappointment in crop response.
llence, the person who collects the soil sample plays a large part
in determining whether or not the test results and treatment
recommendations are applicable. lf the person who collects the
sample does not take the time and make the effort to get a repre-
sentative sample, a soil test should not be made.
Procedure
l. lt is best to collect samples when the land is dry enough to
plow. Summer and fall are ideal.
2. Divide the held into areas in which all the soil looks alike and
has had the same cropping, fertilizer and lime treatment. Col-
lect a soil sample from the held or from each area as follows:
Il. Use a sampling tube, augur, or spade.
f. Collect 10 or more equal-sized cores from the surface to plow-
depth, a minimum of 6 inches.
5. Place all the cores in a clean box or pail and mix thoroughly.
Remove one pint of the mixture from the box or pail and
spread it on a clean paper to air dry. DO NOT HEAT!
fi. Place the dried soil in a soil sample carton or clean paper sack. g
6

 7. Identify the sample by putting the farmer’s name and address
and Held name or number on the container.
8. Take or send the sample to the local Extension office or lab- _
oratory and Hll out the soil test report form. (See detailed in-
structions that follow.)
CAUTION: Avoid small and unusual spots in the held such as
old lime and manure piles or hay stacks, small garden spots, and
fertilizer bands, and stay at least 10 rods away from limestone
gravel roads.
When To Collect Samples
Soil samples can be collected any time of the year except when
’ the ground is frozen or saturated with water. However, it is easier
to prepare the sample if the ground is dry. There are several ad-
vantages to collecting samples in the summer and fall: (l) the
results are reliable for fall or spring treatment; (2) the ground is
usually dry and farm work has usually slackened; (3) the work
load in the soil testing laboratory is usually low; (#1) the person
making the recommendation has more time to consider each test
result individually; (5) the farmer has more advance notice of his
lime and fertilizer needs; and (6) lime, phosphate, and potash can
be applied in the fall when the land is dry and firm whether the
application is for fall-sown or spring-sown crops.
` Dividing the Field r
lf the held or area in question has ‘more than one soil type, a
composite sample should be taken from each soil type, provided
each area is large enough to be treated as a unit. Otherwise, the
major soil type should determine the treatment. Likewise, if a
part of the field has been limed and/or fertilized differently than
other parts, a composite sample should be taken from each treat-
ment area.
Fig. 1 illustrates a field that includes differing soil types and
varying past treatment. lt also illustrates a method of labeling
composite soil samples from a field such as this. If the soil type
and past treatment are uniform over an entire held or area, only
one composite sample needs to be taken.
7

 Ridge Top l‘A ////
//
x'
""`·———----~'/ _ gx
x" `
Slope 2-A ,/
Bottom 3-A __
Limed 4-A
Fig. l.—Field diagram for collecting soil samples
Sampling Tools
A soil sam lin tool, a clean ail or box, and soil sam le ba s
P g P P g
or boxes are needed when collecting samples. The tool used can
be either a soil tube core sam lin tube, a 3 to l inch soil or
P 8 4
wood augur, or a spade. Of all the tools listed, the soil tube 1S
most convenient and accurate.
Fig. 2 illustrates l10w to use the various tools when collecting
soil samples. Each soil core should extend from tl1e soil surface to
plow sole depth, or a minimum of 6 inches.
[ . ..
-3 ance ¤/2
`§ thick V
$:2:$:i;·:¢:¥:?:7:?:i:?:¥:?:·:   :-:-:-:-.¥:¥:·:¥:¥:i:i: · :7:4}:·:·:·i·:-:·:·:·:·:-:· iiiiiiif: Zi- é`?.  
Fig. 2.·-Tools for collecting soil samples _
Collecting Soil Cores
A soil sample should be a composite of 10 to 20 individual cores
taken from the held or area to be treated. Fig. 3 illustrates the
tigzagging fashion that should be walked when collecting the soil
cores that will make up the composite sample. The reason for zig-
zagging is to avoid following il line where previous applications of
lime or fertilizer may have been unusually heavy.
8

  R /  \®,@
Fig. 3.—FieId diagram for collecting soil cores
Handling the Sumple
As the cores are collected, they should be dropped in a clean box
or pail. When the selected number of cores have been taken, the
lumps should be crushed, the rocks removed, and the composite
sample should be mixed thoroughly. Then about a pint of the
soil should be put in a sample bag or box. This is the sample that
will be delivered to the local Extension office or the testing labora-
tory after it is labeled with the farmer's name and address and the
field or area name or number. It should be air-dried before delivery
to the testing laboratory. Soil sample boxes can be obtained from
the local Extension office or the central laboratory.
THE SOIL TEST REPORT FORM
()n the following page is the portion of the soil test report form
that should he filled in by the farmer or gardener. This form is
available at the local Extension office and the central laboratory.
The information requested on the above form is useful in ad-
justing lime and fertilizer treatments to compensate for past crop·
ping and lime and fertilizer treatment, to the kind of soil being
cropped and the crop to be grown. Lime applied within the past
three years has not reached the peak of its effectiveness. Likewise,
manure applied within the past six months will still yield some
benefits. Thus, farmers should get credit for certain recent past
practices when making fertilizer and lime applications.
9

 DATE .... . . ..........4....,....,....   INFORMATION FROM FARMER: SOIL TEST REPORT
SAMPLE VCOIINTYV W 7 T 7 7 SOIL TYPE DRAINAGE
IDENTIFICATION GOOD rj
ACP   [jr NOJ; ing i i i fir WMEIJ '] WPPOR  7
FERTILIZER APPLIED IN PAST LIME APPLIED IN PAST 3 YEARS
I2 MO. (LB A) l l   -T0Nsr,A CROP. .. .,....   ..     . . . . ..
N M Risek §m»Hi+ERA¢st¤z¤T»&?i§+' NEW S¤¤¤·~¤ n
KO 5 YEARS .     LB,A ESTABLISHED [1 CHECK ONE (J) 7
PREVIOUS CROP MANURE WITHIN 6 MONTHS OF ACRES IN FIELD  ....., . ....,   .,....   ....   U
YIELD A PLANTING   ..,. ..   TONS/A N0. OF BORINGS   . . .   . ...,.
TESTS
TO BE
MADE
I I)
` [W NAME   ,..,   . .... . .... .,   ....,.. . ..,,...   ...... ,     .... , .,,... .. .... _
MAIL
2 ‘1 Anmztss .. . ..     ........ . ....   .. .... . ,... . ,....   .
  Y
\Vhen no soil tests are made, lime and fertilizer treatments must
he based on a knowledge ol` past treatment and recent crop growth.
However, such knowledge, usually known only by the [armer, does `
not tell il` soil acidity or a single plant nutrient is determining the
level ol crop production. Neither will it tell if one or more of the i
plant nutrients is in abundant supply or if soil acidity is at the
desired level.
\\'hen no soil test is made it is salest to assume that both lime
and lertilizer are needed, then apply fertilizer and lime assuming
that the lertility ol the soil is low and it is moderately acid.
The lime and fertilizer recommendations listed on pages ———
through —— are given as ranges in tons ol lime and pounds of N,
PSU; and KBO per acre, to be applied alone or in combination for
any particular soil test level and/or cropping history for the various
IICILI (TOPS. rI`Il€ })LlI`I)OSC of IIICSC I`3Ilg€S is to I)€I`HlI[ 0116 to (Il`21\\’
upon his knowledge of the production potential of the soil and
10

 other farm conditions to determine the most realistic lime and
fertilizer treatment.
In determining lime and fertilizer treatments the following
factors should be considered:
(a) Mlhere the test value lies within the soil test category of high, ‘
medium, or low, that is, whether a sample tests in the upper
‘ or lower portion of the low or the medium or the high range. ·
(b) Yield potential of the soil.
(c) Productivity goal of the farmer.
(d) Chemical characteristics of the soil.
(e) Recent past treatment.
The higher rates of treatment listed in each test category are
to be used when the soil is capable of producing (with proper
fertilizer and management) at least 125 bushels of corn, or 3 tons
of legume-grass hay, or 3,000 pounds of burley tobacco per acre.
The soil treatment for a specihc condition should be adjusted up-
ward or downward on the basis of the hve factors listed above.
Of these factors, (b) will be discussed on page 12 and (c) is self-
explanatory. Factor (a) justihes a downward adjustment of the
fertilizer rate in proportion to the closeness of the test value to the
next highest test category. Factor (d) is primarily concerned with
. the ability of the soil to supply potassium and phosphorus (see
page 13). In factor (e) a downward adjustment should be made
for recent applications of lime or manure.
The factors to be considered in determining soil treatment are
interrelated, and all of them should be considered. Case A—Let’s
assume that: (1) A soil test value is at or near the lower limits of a
V particular category, (2) the farmer’s yield goals and management '
abilities are high,   the productive potential of the land is high,
and (4) the land is derived from sandstone. ln such situations the
treatment should be at or near the upper limits of the suggested
range. Case B—At the other extreme 1et’s assume that: (1) A soil
test value is near the upper limit of a particular category, (2) the
farmer’s yield goal (or the productive potential of the soil) is low,
and (3) the soil has a high rating for release of nutrients not
necessarily shown in the soil test (see pages 17 and 18). The rates
of fertilizer recommended for Case B would be considerably less
than for Case A.
11

 ADJUSTING LIME AND FERTILIZER
RECOMMENDATIONS
Monure
For each ton of manure applied, reduce N recommended from
fertilizers 6 pounds, PZOS 5 pounds, and K2O 10 pounds. See Cir-
cular 593, “Farm Manures."
Tobocco stolks
For each ton of stalks applied, reduce N recommended from
fertilizers 30 pounds, PZO5 10 pounds, and K2O 70 pounds. See
Leaflet 269, "Tobacco Stalks and Stems." .
Tobocco stems
For each ton of tobacco stems applied, reduce N recommended
from fertilizers 27 pounds, PZOG l0 pounds, and K2O 140 pounds.
See Leaflet 269, "Tobacco Stalks and Stems."
Liming when heovy nitrogen cipplicotions ore mode
The lime recommendations in this circular are made on the
assumption that the recommended nitrogen rates will be followed.
However, some farmers apply more nitrogen than is recommended
in this circular, especially on corn and tobacco. If this practice is
continued over a few years, lime applications should be adjusted
upward from the recommended amounts, or should be more
frequent. The amount or adjustment depends on how much more
nitrogen is applied than is recommended. Usually the amount of
lime applied should be increased by half when the recommended
amount of nitrogen is doubled. If you grow corn or tobacco con- V
tinuously on the same land and apply nitrogen equal to or above the
recommended amounts, you should check the acidity level frequent-
ly, to determine how often to apply lime.
Production potentiol of the fond
Depth of rooting zone and poor physical structure can easily
be, and often are, limiting factors to high crop yields on some Ken-
tucky soils. These soils are apt to have a hard pan, fragipan, or
clay pan somewhere in the soil profile that prevents proper drain-
age and restricts root penetration to shallow depths. In other soils
bedrock may limit the depth of the rooting zone.
12

 High water tables, compact pans, or bedrock also limit air pene-
tration to the shallow depths. Plant roots will grow no deeper in
the soil than air can go. Usually the depth to which a dark color-
red, brown, or black-extends into the soil profile is a good indica-
ton of the depth of air penetration and thus the depth of the rooting ·
zone.
A soil capability map shows the depth of the rooting zone. lf .
you don’t have a capability map, a soil core sampler or post hole
digger can be used to estimate the depth of the rooting zone.
Soils that break up in clods that are difficult to pulverize when
dry have poor physical structure. In such soils there is a tendency
to crust when dry, water penetration is slow, and water availability
is low. These soil characteristics limit crop yields to a level below
those of soils with good structure even though the fertility and
management practices are the same on the two soils.
Fertilization programs should be adjusted to the production
potential of the land as estimated by the effective rooting depth
and physical structure. A shallow rooting zone, from 12 to 15
inches, will in most years, limit corn yields to about 70 bushels per
acre and tobacco yields to about 1,500 pounds, even though the
fertility levels are high. Soils that have limited yield levels such
as these should not be fertilized for high yields, such as for 125
bushels of corn or 3,000 pounds of tobacco, because of the eco-
nomics involved.
Phosphorus and potassium releasing potential
Routine soil tests in Kentucky indicate the amounts of phospho-
rus and potassium available at the time the analysis is made. Such ,
soil tests do not refiect the total amount of phosphorus and potas-
sium a specific soil is capable of releasing throughout a growing
season, but the soil tests are useful in giving a general soil test
level. Therefore, the fertilizer should be applied according to the
general soil type as indicated in Figures 4 and 5.
Figures 4 and 5 show the areas of Kentucky that have soils with
different potentials for supplying phosphorus and potassium. The
lines separating the soil areas (Fig. 4 and 5) indicate rough ap-
proximations of where the transitions between soil types with
different potentials occur. Hence, close observations would show
instances where the soil type in one category extends a few hundred
feet or even a few miles across the line into another category. The
13

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 transition from one soil area to another therefore is gradual along
most of the lines. There are few, if any, places along the lines where
the change from one soil area to another is abrupt. Neither are
all the soils within an area uniform in potential for supplying
phosphorus and potassium. Thus, there are areas of varying size
in any soil area designated in Figures 4 and 5 that are lower or
higher than the rating placed on the area generally.
In the alluvial soils along the Ohio and Mississippi River (Fig.
4), the phosphorus supplying potential varies greatly, depending
largerly on soil texture. The finer textured soils release more
phosphorus than soils with coarser textures. The coarser textured
soil areas vary in size from small spots in a field to several acres or
a whole field. These areas can usually be located by observing the
soil texture or by checking past fertilizer response.
In the central and northern Kentucky areas the soils are derived
from high—phosphate parent materials. However, in these areas
also there are variations in the phosphorus content and the poten-
tial supply of it because of variations in soil type and in the amount
of erosion that has occurred. In the Eden soils, the ridge tops are
apt to be lower in phosphorus than the slopes because of the erosion
that occurs on the slopes. Erosion continually exposes the subsoil
or keeps it near the surface, and the subsoil, being younger and
nearer the parent material, is generally higher in phosphorus than
the top soils generally found on the ridges. However, even though
the eroded soils on the slopes may be higher in phosphorus, they A
may be less productive because of poorer soil structure, lower
permeability, and less available water.
The soils in the Eden Hills area of northern Kentucky and
surrounding central Kentucky are usually rated high in potassium
supplying potential. However, small areas on the ridge tops are
low to medium in this characteristic. This variation is caused by
a different soil type than is generally found on the slopes as a
result of less erosion and more intensive cropping on the ridge tops.
Soils on the slopes and the alluvial soils along the streams are
normally high in potassium supplying potential.
The soil areas rated medium in potassium supplying potential
are largely derived from limestone. Some soils in these areas are
low in potassium supplying potential, because of variation in soil
type and shallower rooting zones.
In the Purchase area and in some counties immediately to the
16

 `northeast of it, a loessal mantle covers the surface. Variations in
potassium supplying potential are caused mainly by the depth of
loess material and of rooting zone, as well as past treatment.
The soils that are rated low in potassium supplying potential are
derived mainly from sandstone. Variations in potassium supplying ·
potential are due largely to variations in soil type, the amount of
erosion that has occurred, and the depth of the rooting zone. ·
In south central Kentucky and in the counties immediately to the
northeast, the soils are primarily a mixture derived from sand-
stone, limestone, and shale. Variations in potassium supplying
potential depend on the kind of parent material that contributed
most to composing the soil. Soils derived chiefly from limestone
are higher in potassium supplying potential than those derived
chiefly from sandstone.
Liming to correct exchangeable acidity
The soil acidity (pH) categories (strongly acid, moderately acid,
slightly acid, and near neutral) referred to on pages —- through
——- in this circular are based on a soil-water suspension test. This
test indicates the "active" acidity (H-ion activity) at the time the
test was made. It odes not directly indicate the "exchangeable"
acidity, aluminum and hydrogen, that occupies the exchange sites
on the clay and humus fractions of the soil.
Exchangeable as well as active soil acidity can be measured by
using buffer solutions to displace the exchangeable aluminum and
hydrogen from the soil clay and humus. This procedure is referred
to as the "1ime requirement" test. The amount of lime required
to cause a given pH change in the soil is determined by measuring
the pH of a soil-plus-buffer suspension. The buffer solution has an '
initial pH of 7.5 and the extent to which the soil counteracts the
neutralizing ("liming") chemicals in the buffer reflects the lime
needs of the soil.
The lime requirement test provides more reliable information,
especially on buffered soils, than the soil-water suspension test does.
The lime requirement test (Buffer based on the Shoemaker—Mc-
Lean—Pratt method, Ohio State University) is made in the central
Soil Testing Laboratory, Agricultural Experiment Station, Lexing-
ton, Ky. 40506.
The amount of lime required to bring Kentucky soils to the
indicated pH according to the soil buffer pH is shown in Table l.
In table 1, pH levels of 6.0, 6.4, and 6.8 were designated because
17

 Tuble 1.-—Lime Required on Kentucky Soils to Adjust Soil
Acidity to Designated pH Levels When the Soil Buffer pH (Lime
Requirement Reading) Is Known
Soil·Bur1er pH Agricultural limestone (tons/acre) required
(Lime Requirement) to adjust soil t0:"‘*
[JH 6.0 {JH 6.4 pH 6.8
6.7* 1.0 1.5 2.0 ·
6.6 1.5 2.25 3.0
6.5 2.0 2.5 3.5
6.4 2.25 3.0 4.0
6.3 2.5 3.5 4.5 ·
6.2 3.0 4.0 5.0
6.1 3.5 4.5 5.5
6.0 4.0 5.0 6.0
5.9 4.25 5.25 7.0
5.8 4.5 5.5
5.7 5.0 6.0
5.6 5.75 6.75
5.5 6.0 7.0
* In some sandy soils, even though the soil-water pH is 5.9 or below, the soil-
buller pH may be 6.8 or above. For such cases, use a nominal application
of about l ton per acre for most crops.
** Limestone needs are listed assuming: (1) The limestone will be thoroughly .
mixed with the soil (2) It will have two years to react with the soil to give
the indicated pH and (3) A good quality limestone is used and at least 45
percent of it will pass through a 50—mesh screen.
these are the approximate pH levels desirable for tobacco; for grain
crops, clover-grass mixtures, and straight grass; and for alfalfa and ‘
alfalfa-grass respectively.
lf hydrated lime is to be applied, use % of the rate given in
Table 1.
\\’hen soil tests are made using the lime—requirement test, usually
two pH values are reported: (A) on the new soil test report form,
the left column (pH) will be the pH of the soil in a 1:1 suspension
with water, and (B) in the right column of “Test Levels" will be
the pH of the soil in a buffer solution (lime requirement reading).
lf the soil·water pH is 6.0 or above, no measurement is made
with the soil in a buffer (lime requirement). For such soils where
:1 pH greater than 6.0 is desired, limestone may be applied on the
basis of the soil-water pH (1:1 soil-water suspension).
18

 LIME AND FERTILIZER RECOMMENDATION RATES
Tcble 2.-For Grain Crops
Soil Test Results Recommendations
g Corni Small Grain? Soybeans?] .
Acidity (pl-I) Limestone, tons/A
Strongly acid—below 5.3 3-4 3-4 3-4
Moderately acid—5.3-6.0 2-3 2-3 2-3
Slightly acid—6.1-6.7 0-2 0-2 0-2
Near neutral—Above 6.7 none none none
Nitrogen Leve1——from Cropping
History, Following: Nitrogen (N)‘*, lb/A
Corn or sorghum— (low) 100-150 30-60 none
Grass legume or legume 60-100 0-30 none
sod- (med.)
Continuous tobacco 4 or more 30-60 none none
years- (high)
Phosphorus—1b of Elemental P/A Phosphate (PZOS), lb/A
, Low—30 lb or less 60-