xt78pk06z88c https://exploreuk.uky.edu/dipstest/xt78pk06z88c/data/mets.xml   Kentucky Agricultural Experiment Station.  journals kaes_circulars_004_584 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. 584 text Circular (Kentucky Agricultural Experiment Station) n. 584   2014 true xt78pk06z88c section xt78pk06z88c F'; ·<’ - ‘ V
I, '·-. "   ' I4 ,
V I ` ”y - Q ·’! "    ,.».._, ; ,--,   -=»—  ~¢~ wazw -·~
I I . I I >       » I    Ja &  .%  
{ _,_, I I __v, _   V     ·        I  ... *_,
  .2%; ,V»v;' .· Lszk   I I ~ ¤ » [ »V-—     -’=» =  V¤ .~.·.               ·»·=¢ T  —· _ ..·.\_  
      »· ,..,   V·V=A`   J? xg? ·' ' x °’‘` . °.’`   .4.. .   ·.,»:v. ;- I   ·` “
. ` ’     .:’2=;·;i >>.;.. f ··-. I iv   _ - __!  i   .,..,,' ·..· · ,_ __ · · `     -»·- ‘ - -"'     ,·*·   -·.:  
    .  M-       izii   ·<...I;· K 9* ·· r .   , —
II,   ·v·_ _     ' ' M N,. " ·· .- " ,··», _> [ _
I.     ., 5 ··-· · J    { _ »::~~;\ x ___ N >  
.     ~ "{\ :`. · ‘_`*-A _.' ..·” ··"‘ .,,. ...  
I . · · ‘   `iv_";;v _ A   _,_,,,¤g¤·V"”' ` ` ` · · —·  .» %,,   ,;T._,§;q{I_g .__\_ _,4·_  ‘>__ ·V
.   7 ` \ ` ,2., 7/ . é  is · > l, {iw   it     \( T·`..,1.=»i in I". V I
  5    ;;3I,  ;   {   (I    "   '  `\ ` ? I \1**`*,{ Y . xx   `, ` ‘..,'
: W3 r` { 3, ,»;,_\;_l§t&~ . 5 ,» ;_:L_ S)   I 2,, I  -. ~ A , 4   Q   wl
V   I ‘·‘ I I?   ‘  ·` “ * ` `t$*:w·i"k,·, *‘;` ._>v""_*1 1
, a  r \ -&»   _. , I I »   . . _ I   , , _ xy   *·_‘ ~J`j=°··.-’;_1·§
 .,  ~;_· :5 ,e,4.-gc  ~ v ~•¤~ { Hf .  · 2 * ·>é~‘;;   , _ *·‘2'·¤>  ——, ,. ,_ ,pq\•;g_ >,;  %   ;;:,,_§;;   · j _ ,.·
                —,       "`3  .‘{;`      
rw ·=¤·    I1. =>-  ·· ‘   ·~ - w"     * f~*‘*»   ·»¢‘··w.-»*%’E?»¢s“+.   ¤>-I  I —   I ~   r~   ·i · ‘
|·____;{r{;`-yv§:="2‘·"9'f,·,·~.;,$éi;2a· ;,_wy}_·'    ·»  ’Y.__ ,{;i??§»;, §*?§¤`§;1,+S,y·»f{·,;¢—»`&~‘é_;_w$»4 I "),__ " ‘* .' Mx,   .\ "
ik; . »'     {E3 x   2     ,,‘,3; i§5;“1?wj     I    ’~¤,   = __ q;¤xl·§·•g
  _`VA   Ir? __._ ;_  ,..._ 3     ~<'_"` ¥ "  i" "   `A ~·_  FE   `“ ‘?§~g ¤ -.   xg .   , ·  K`_  M. A2,- ;  {
  ··A.,     ’     *   I
.; A‘·= Q   —’ isi? T ‘—A‘ I       ,_A.       ‘§‘“—¥’.":I*‘?YS?%?;i Q .L»`   ·e;=*T'    =e».4  M; 
 *'   v'Q;{’r»·y , -‘_ I _¤~’·‘.»_`.—. . _‘ gw-   ·» ~»,.·{;<.   ·‘ ·` :§;   ¤<;U··m.·.,-   i { W · °z *,11* .#3’z!’   k7·;Z ..» `
[ {,.5,       ,,_;l _,v`_, ,j>'s..A_     Ima I,   _ .4 ;_ xx,-L_   .,T,{_ ,, ·.»I     gr wr I ;,» , A _. ax ~_ `W wx II
,,, A   .» »_.,   x. . — » ;   3 · =·‘, - *"e ‘ ,;,·':vz!.?~:.. ;\ ’ v¥~,_·»·r 2.   ,·, · » .·q» * _ :»`: .
 $_ ~ Q_;v’-ng);  L   _, ,·_ I 4 _ ..`. \~L   {I;] ’ E- \ II;   :,‘\·.; `I,   -4%;}.   M ;;»¥,£:" • 0*n  
Z  ,1 ` , F5 ny, I  _   \'.;;>,‘;".,J‘».; M . ., ·  - • ·‘ ’>¤·;.`·I_*\-Q   yi! ‘_   ;y';I
W/1y-W/1en —W/1ere
CIRCULAR 584
(FILING CODE: I—2—I)
I
  AGRICULTURE AND HOME ECONOMICS

 
 I O • •
Controlling Soil Acidity:
F Why - When - How
BY STAFF MEMBERS, AGRONOMY DEPARTMENT
UNIVERSITY OF KENTUCKY
Why Are Most Kentucky Soils Acid?
A ' Why Control Soil Acidity?
Need Lime?
What Kind Should Be Used?
How Much Is Needed?
When and How Should Lime Be Applied?
Can Soils Be Overlimed?
You will find answers to these questions in this publication.
wb Q ¢
Is soil acidity limiting crop yields on your farm? If so, proper use
of liming materials to correct soil acidity will increase your profits.
4 A sound liming program is essential to successful soil management.
The use of lime is one of the oldest farm management practices, but
many farmers do not understand why it is needed nor do they realize
the benefits that can be derived from its wise use.
WHY ARE MOST KENTUCKY SOILS ACID?
A soil is acid when acidic elements (hydrogen and aluminum)
have replaced the basic elements such as calcium, magnesium, and
potassium. Soils that were formed from rocks low in basic minerals
were acidic from the time they were formed. On the other hand, those
soils derived from rocks medium to high in basic minerals always
become acidic when rainfall and temperature conditions are similar
Io those in Kentucky. ln such climates there is ii slow but constant
formation of carbonic acid from soil water and carbon dioxide given
off by plant roots and inicroorganisiiis in the soil. At first. this acid
is used up in dissolving and removing calcium. magnesium and other
base-forming cations fi·oin the soil. These elements, in turn, may bc
used by plants or lost in the water which leaches through and drains
from the soil. \Vhen the soil becomes more and more acid, the acid
will actually dissolve part of the soil particles. Appreciable quantities
3

 I M0
CROPY • ‘ _
2 i." Fig. `l.—On strongly
E ` °Q, acid soils toxic elements
Z TOXIC ELEMENTS ` ind. excess alcildjity will
Z     II’HIl' CTOP y'I€ S EVEN
; though there is an abun-
$ dance of available intro-
(*5 • é gen, phosphorus and po-
Z • 0 tassium.
AQ L
INCREASING FERTILITY  
NO LIME
LIME QL ’
p
41**0
c¥~OQ
D TOXIC ELEMENTS
KI: EXCESS ACIDITY
Fig. 2.- Liming strongly 3
acid soils reduces the soil Z
acidity and the solubility Q •
of toxic elements, there- at-I  
by increasing crop yields. U 0 I
L
Z lim
INCREASING FERTILITY  
LIME APPLIED
<1I` llllllllllllllll und lllLlllg2lllCSO {ITC dissolved and nrc tukcu up by plants
jjI`()\VlIlg ()Il such soils.
WHY CONTROL SOIL ACIDITY?
N11 1I<111I1I II1¢· 111<1sl widvly l`l‘(‘l)QIIIZ(‘(l l'(`ilS()ll I-()l` npplyinng Ii111¢·
In soils is U1 adjust II1¤· 2l(‘l(lll)` I<1 Il I<·\·<-I <`L`IS tI10 ;1\‘;11I;1I1iIity (ll. (.`(‘l`lLlIlI
4

 elements in soils. In acid soils, such elements as ahuninum and man-
ganese are particularly soluble and also may be present in sufficient
quantity to be toxic to plants. Consequently, when liming materials
are applied, soil acidity is reduced and the solubility of toxic sub-
stances is reduced sufficiently to prevent crop injury. On the other
hand, when acidity is reduced by liming, the phosphorus, molybdenum,
calcium and magnesium are made more available to crop plants.
In addition, Hxation of atmospheric nitrogen by bacteria is encouraged.
which in turn makes more nitrogen available to the growing crop.
Maximum returns from fertilizer dollars cannot be realized unless
acidity is controlled through the judicious use of lime.
Lime is not fertilizer. Actually lime sets the stage for efficient
crop use of the nitrogen, phosphorus, potassium and trace elements
present in the soil. Unless the acidity problem is corrected first,
maximum crop yield can never be obtained, regardless of how much
fertilizer is used. One of the major benefits of lime comes from its
ability to change manganese and aluminum to less soluble forms
that are no longer injurious to crops. An additional benefit of the lime
comes from its prevention of phosphorus from being “lixed” as alum-
inum and manganese phosphates, which are relatively unavailable to
plants. For that reason, the phosphorus already present in the soil and
that added as phosphorus fertilizer are used more efficiently by plants
. grown on limed soil. Lime makes conditions favorable for growth of
microorganisms that fix nitrogen, decompose crop residues, convert
ammonium to nitrates, and at the same time it chemically discourages
growth of harmful fungi and many plant diseases.
NEED LIME?
Recent summaries of soil test results indicate that at least three-
fourths of the fields used for crop production in Kentucky are too
acid for maximum production of most crops, particularly the valuable
legumes. Proper use of good liming materials can counteract this
excess acidity and result in higher yields, when used in conjunction
with recommended fertilization practices (Fig.  
You can get additional information about the lime needs of a
particular field by taking a representative soil sample, along with
cropping and liming history of the Held, to your county agent for a
soil test.
The need for lime is most commonly determined by measuring
the degree of soil acidity which is expressed in pl] values. The pH
4 scale ranges from () to 14 and is really a shorthand expression of the
amount of active acidity (concentration of active hydrogen ions) in
the soil.
5

 _, ,~x   JQ A   A   .. ~/ -
l /w¤·`· 0 7   *   I-;  l n dll; Y (C 5f·_;`,,;llr,f;,,T<’iQ4  ` *" * 0   i al   
;·, ;.£_·g.   _;,;,—;Q?_5` ;·{L_`;,,   L. (wg:-I._· ?,,[}h;_2$y‘Ufi  ig;. ·_,  _.- {ja Ti  {gg .,%,53*
ll? rf- ’ *   i\'·’i· rr W ii »     '~   ’·`l`»l¤*-nf ~i¥f‘=¢`¤‘ ¢.l»   Wl P;·~¥l*.~‘_gl.   .‘¢.”i '· · ,"f·"‘· ~¤   I 't ' ll Bil? `Y QCFIV · `.  "· I'! ·   il 4'F"
··/ -4);, ‘       . I  {qi;     ye rpt X jj? l.? > kar-.A;—  
V Q'? _   \.P‘· { _i· I-y*_-',°~ \ ;{'_y};.$¢»,,§’·»;,_Q}’_*AZ ·.1_·i___·»-_Q   ’{_§
  “ . ·' l' ’   . . . f’.s A`’,. »    ··'A   »·~v   `° 
  .   A·.A . ·:’ .       -,-A.    
  vrvf     = ‘``    A»»--*      
"‘"*’:   "   ·. '   1F' ¢· #     'awt ‘ ‘-w   r=‘i%;~   z»    _;’· -   ‘·Zi.=‘wa .;,’ *  
A    "          "  
‘ r                          
’ I ‘—   ‘           ·‘ " . , Q   ‘*·r·‘ »   Q. ..»E.     ;‘‘ `=-· . ~».-xv W      
Fig. 3.— The effect of liming on the growth of corn. (The plot on the left received
lime.) doth plots were treated with nitrogen, phosphate and potash.
Notice from the pH scale that pH 7.0 is neutral, whereas all values
hi ther than 7.0 are alkaline and an >H value below 7.0 is acidic
I—» l
(Fig. 4). These numbers are Iogarithms; consequently, there is 10
tin1e.s· more acidity at pH 5 than at pH6, which means that more lime ‘
is needed to make a one unit pH change when the pH values are low.
'I`he pH alone does not denote the amount of liming material re-
quired to make the desired adjustment in soil reaction or pH. Il: it
ph
SOAP
LL.!
Z H
;;' SEA WATER
sc
zi E HUMAN moon
PURE WATER
7 FRESH MILK
RAIN
>
Q
0
5 SOUR MILK
ORANGE JUICE _
4 Fig. 4.- pH scale. (See text for ‘
explanation.)
LEMON JUICE .
3
pH
  '

 were, all soils would require the same amount of lime to make the
same change in pH. Such is not the case. The amount and type of
clay, as well as the amount of organic matter in the soil, affect the
amount of lime required to bring about any particular change in soil
reaction.
Coarse lime particles dissolve more slowly in soils than Hue
particles, and complete dissolution of either may take as long as four
or five years. Therefore, the pH of a soil a year or two after lime
has been applied is not a good indicator of the need for additional
lime to promote better crop yields. In other words, the pH value
may indicate that more lime is needed than is actually the case, since
some of the lime from the last application may still be reacting. To
insure an accurate estimate it is important to complete the cropping
and liming history questionnaire when you send in a soil sample.
The pH difference among soils due to rates of lime (Table   has
been statistically different; in almost every case, but crop yields (corn
on the Pembroke and Ladirro clover on the Grenada) have not been
increased by the use of more than 1.5 tons of lime. This comparison
would suggest that only a small amount of lime was necessary to
_ raise the pH enough to lower the solubility of aluminum, manganese,
and other toxic substances to the point that they were not injurious
to the crops and that the active hydrogen neutralized by the addi-
tional lime was not a limiting factor. For these reasons, soil texture
and past liming history must be considered. as well as plrl values. in
order to make good liming recommendations.
WHAT KIND SHOULD BE USED?
The three main points for judging a liming material are: 1) the
total capacity to correct soil acidity; 2) the rate at which it makes the
change; and 3) the relative cost of the correction. Ground limestone,
because of its wide distribution and relatively low cost, is commonly
used as a standard liming material and other materials may be com-
pared with it. Limestone for use as a liming material should have a
neutralizing value of at least SO percent of that of pure calcium
carbonate. The limestones in Kentucky are dorninantly calcic (cal-
cium carbonate) with neutralizing values ranging from 85 to 95
percent.
Dolomitic limestones contain considerable amounts of magnesium
n carbonate and have slightly higher neutralizing values than calcic
V limestones. At present, there is no experimental evidence that thc
dolomitic limestone is more effective on most Kentucky soils than
calcic limestone, but if the cost is the same the dolomitie limestone
should be used, if available.
7

 Nlarl is being used in some sections of the state as a liming ma-
terial. Xlost of the marls contain some magnesium and have neu-
tralizing values of 40 to 7() percent. This soft limestone material is
good for use in liming soil, on the basis of neutralizing value, if its
cost is comparable to ground limestone.
()ther materials which may be economical in some particular
situations are burned lime, hydrated (slaked) lime. and basic slag
(byproduct of the steel industry).
Table 'I.- Comparable neutralizing rates of liming materials
T T T ¢_ Neutralizing Cmnparulwle
Liniing Material Value \Veigl1l.s·
_Gn>und Limestone (CaCO;‘) ...................... 90% 2,000 lb
llydratcd Lime [Ca(Ol’l)2] ....................... 133% 1,300 lb
Burned Lime ((1110) ......................i............. 180% 1,000 lb
Basic Slag (calcium silicate) ...................... 85% 2.500 lb
Xlarl (mainly CaCO.;) ..,.......................,..... 50% $.600 lb
The quality of limestone is also dependent upon the size of the
individual particles. which is expressed in terms of the mnnber of
openings per inch of the screen, through which the material will
pass. Neutralizing value of the lime is fairly constant for a given
quarry. llowever, one should be concerned about the particle size of
the lime, since it largely governs the rate of reaction of the material V
once it is applied to the soil.
Table 2.- A guide to the reactivity of lime in respect to particle size
Particle Size Soluble Wi1l1inr3 `1'e;n·.s
Larger than 4 mesh (li in.) ............................................ 0
4-8 mesh .............................................................................. 10%
8-20 mesh ..........................,................................................. 30%
20-60 mesh .......................................................................... 60%
Passing a 60 mesh screen .................................................. 100%
In the absence of a set of screens to check the particle size of
the lime. a visual comparison can be made as in Fig. 5 below.
Considerable experimental data have been accumulated concern-
ing the desired particle size in agricultural limestone. The larger ma-
terial may be ellective over a longer period of time, but the more
line material it has. the more rapidly the soil acidity will be corrected.
Ground limestone should have a neutralizing value of at least 80
percent. with at least 80 percent of the particles passing a 10-mesh ‘
screen and -10 percent passing a ($0-mesh screen.
8

 LIMESTONE SEED
_ u Q   ,1};
. ¢¢"   ·-
+l0 Ki   »»4·4E   s   verch
Mesh     "   •  . ·=  
  gr ~* ,
_' nga    Q‘•·$·~‘·~.;·".s¤  
*0-20 éieg; ZT?} ws    
Mesh f’-»¢'§;; SM X n       Korean
rss; c,~·~* —»,·$·;< ¢._  
‘ ’;§§§°·       Lespedeza
    » ;£_ gj mg"
2iL§4*¤»32, I r . ~
2°‘4° 4   ·’:§·!;5s£g` e
Mesh ?¤e;»r.:»z——.;2n,:/; gx *~· as ·, d
glgcig-zi?   · *§Q xw , Re
* 4 `*;.»·Z' e_ ` ’ 2*
+ .
  »
··Z?»;cy-·**· .
  \“ v, '
40-6° >;€**“ ?`=i. X ' ° J
" »»A’<~'*•'Ya‘?f*Y'? '
Mesh   x§»z;?,,; 1 rl
r *~·m?$‘ af? · .
` s` =?:;.~.~ · W · Tobacco
gt? :n.,i1¤`iv‘ i ° ry,
; z il"   •. V
Fig. 5.-—A comparison of various sixed particles of ground limestone with crop
seed of various sizes.
HOW MUCH IS NEEDED?
The amount of lime required depends on the kind of liming ma-
terial used, the texture ol the soil, the organic matter present in
the soil, the depth to which the soil is plowed, and the particular
4 crop and cropping; sequence to lie lollowed.
An intimate knowledge of how certain soils react to applied
lime is necessary hellore a prediction can lie made ol. the amount ol
lime required to raise the pll to a desired level. For instance, lah-
9

 oratory determinations of the amount of pure calcium carbonate
necessary to change the pH from 5.5 to 7.0 have been made for
several soils of the state. Nlercer silt loam and Loradale silt loam, both
from similar geologic formations of limestone and shale, react dif-
ferently. Mercer requires 4.4 tons and Loradale 5.4 tons of ground I
limestone per acre to produce neutral conditions in these soils. In the
same comparison, Culleoka silt loam, developed from calcareous silt-
stones and sandstones, requires 2.5 tons per acre. Thus, it is apparent
that the type of soil determines, to a large extent, the amount of lime
needed to correct the acidity.
The organic matter in a soil has a high buffering capacity or re-
sistance to a pH change, but the organic matter content in most of _
Kentucky soils would not differ enough to be of great importance.
X/[any farmers are now plowing deeper than 6 inches because
they have more powerful tractors than in the past. This means that
more limestone is needed to correct acidity of the plowed soil. If 4
tons of lime was needed when a field was plowed 6 inches deep, 6 tons
would be needed when it is plowed 9 inches deep because the lime
is being mixed. by repeated plowing, with 3 million instead of 2 mil-
lion pounds of soil. assuming uniformity of the soil properties with T
depth.
The soil pI[ range most suitable for the common crops is shown _
in Fig. 6. Xlany of these crops will grow outside these ranges, but
will produce best within the ranges shown. Corn, for example, will _ y
grow over a wide range of soil pH, but pH 6.0 to 6.5 is most de-
sirable_ especially if the corn is grown in a rotation with elovers or
other legumes. The Irish potato will grow at a much higher soil
pH than indicated, but a scab disease is favored by less acid condi-
tions. which in turn lowers yield and quality of the crop. Tobacco
is a similar example; soil borne diseases may often be favored and
nutritional balances upset at near neutral soil pH.
In summary, the amount of lime to apply depends upon a number
of factors including cropping sequences. All of these factors must
be considered along with results of the pH determination by the
soil test. in order to reliably estimate the amount of the liming ma-
terial necessary to raise the pH to a desired level.
WHEN AND HOW SHOULD LIME BE APPLIED?
Most forms of lime may be applied at any time of the year or
of the crop rotation. It is best. however. to apply the material well in I
advance of planting the crop in the rotation that has the highest lime
requirement. usually it will be a legume, such as alfalfa. It is im-
10

 pH
ckors 5.0 5.5 6.0 6.5 7.00 7.5
ALFALFA -—- Y .._
swam ctox/ER --1 .. .....
ALSIKE cLo\/ER 1;;..1
RED c1o\/ER 1j.._..1
wane CLOVER K-_..._..-
BARLEY E }; .-
WHEAT 1;.........1
com 1Y...._—-
GRASSES $1........1
OATS ;;l.--
SUDAN GRAS5 Kit--
RYE j.__.___1
soraoaum (LT1
5oYsEAr~1s $1...11
roBAcco 1.__..§Y
vE1<:1-1 Y._.....Z_Y
Fig. 6.— The best pH range for some common crops.
portant to get the needed lime on the land at the most convenient
time, but as far as possible in advance of the desired crop.
_ Strongly acid soils should be limed 6 to 12 months in advance
of seeding alfalfa, sweet clover and other legumes because the full
effect of moderate to heavy applications of limestone will not be
rapidly reached. Consequently, do not expect a rapid change in soil
pH as measured by soil tests. Three to four years will frequently be
I'€qLl1l`€d fOI` 21 l]€3.Vy 3.ppllC2ltlOl] of gl'OllI'](l llITl€StOl1€ to 1'E|.lS€ tl]G  
to the level which many have thought to be the optimum for most
crops. Table 3 illustrates the seemingly small changes in acidity, as
reflected by pH from various rates of limestone applied to 3 silt loam
Table 3.- Effect of finely ground limestone on the pH of three silt loam soils
Lime Original pH After Liming-Year
Soil Type T/A pH Ist 2mI 3rd
Pembroke sil 1.5 5.4 _ — 5.5 6.3
6.0 - 5.8 6.5
6.0 - 6.6 6.6
12.0 — 6.6 7.0
Grenada sil 1.5 5.2 5.8 5.7 5.8
2.0 6.1 6.0 6.5
6.0 6.6 6.5 6.6
12.0 6.5 6.7 7.1
Dickson sil 1.5 5.7 — 6.0 6.0
6.0 - 6.0 6.2
6.0 - 6.4 6.5
12.0 - 6.5 6.7
11

 soils. Although the change in pH was slow, the lime was very bene-
ficial to crop growth.
Experimental data and the fact that srrccessful farming is not a `iorre
shot" brrsiness dictate that a farm liming program must be a continuing
thing. Cropland should never be neglected to the point that it be-
comes strongly acid. Lime requirements should be checked every  
or 4 years to determine the necessary maintenance applications.
For such special crops as tobacco and potatoes in continuous
culture, it is considered most desirable to apply any needed lime in
the fall after the crops are harvested, in order that the major lime-
soil reaction will occur before the next crop is planted.
Xlost of our soils are likely to need some maintenance lime every
4 to 6 years, when used in row crop rotations with high rates of
fertilizers containing such materials as ammonium sulfate. For every
pound of sulfur applied, in fertilizers or fungicides, theoretically about I
3 pounds of limestone will be required to neutralize the acid formed.
.~\nnnonium nitrate and urea also tend to increase soil acidity slightly
because hydrogen ions are released when ammonium and amine
forms of nitrogen are converted to nitrate by nitrifying bacteria in
soils.
Crassland type of farming may require an approach somewhat
dillerent from annual row crops. It may be advisable to use high
rates of lime that will be elfective for a period of S to 10 years, or A
until renovation and reseeding are anticipated. A permanent pasture
or hay crop will benefit to some extent from surface applications, brit
many years are required for surface-applied limestone to penetrate to
plowing depth without cultivation. In \Vcst Virginia, a top dressing
of 1.5 T/A of hydrated lime (equal to 2.3 T/A limestone) on a per-
manent sod raised the pH of the top 1.5 inches from 5.2 to 7.0 after
13 years, while the pH of the 5- to 7-inch layer was increased only
from 5.0 to 5.6. This observation and other data show that limirrg
materials applied on the surface move very slowly to lower depths,
especially on the heavy textured soils. On such soils, if the subsoil is
acid, and high-lime—requiring crops are to be grown, plowing under
half the lime and harrowing in the remainder will help neutralize
the entire plow layer. For maintenance purposes, on soils used in
rotations and already having a somewhat favorable pH, all the lime
may be plowed under with a sod or cover crop. This method will
save labor and spreading costs, and it may speed up decomposition
of the organic matter.
There are many ways to apply limestone. but it should be applied
in a manner that will keep the finer dust particles, which are most V
effective. confined to the field being lirned. lf the very fine particles
12

 are carried away by wind and only the larger particles are left, the
correction of the acid condition of the soil will be much slower and,
consequently, crop response will be disappointing at first.
Much of the limestone spreading done by commercial spreaders
is by trucks equipped with hopper-shaped bodies and endless, or
screw—type conveyers which continuously move the material to the
spreading mechanism mounted on the backs. The two types of spread-
ing mechanisms are the fan, or spinner type, and the transverse COI]-
veyer type. Of the two spreading mechanisms, the transverse COI]-
veyer is preferable from the standpoint of getting a uniform spread
and preventing loss of the dust due to wind. The fan or spinner
type spreader depends on the force with which the lime is thrown
.  if I  T `  if ```‘'  ‘  V ks: W. ---.   `·‘·. ·»=‘=··"€" *·"’= 
. .~-.....-..». L: ;.. . ....  . ·....-.   `-:v> at-  ‘‘·=i   V·‘,`?   ’`i..   ‘”;‘’   `‘‘`‘.-;   =v=   ie?
    »:=;;;     e~e»~   ir.    
p  ., ...... _ _ _ _ j' · ` K   I
      ·»»‘ it `''```` ’ illi    V   ___.i  ip,   V 5  Ji ? 
··,‘       ·:‘·   ·‘`··'i4·     ··  =  - r  —·
  ._..t   »*   ,<.·;e V ..··— —    .»~..··¢. ...’   -. .. 0
     _ ,, _   ¤°’» , <<§;y ;j< _... ,,p  I Ji,   [ _,    
;- -:2%.-,   ··M·‘ ·  §~ ,‘·,~·~   ’ - ·- .;‘;»~•-··r.* "   ~ ,..   ,   4**
  °* ·v*7'i.1¤w~;;;;¤<·*é¥%”**·’·/*“*‘ . ‘ if ‘ .· . <»     ei  ’‘‘.i   »·--¢·’ *      
JL.-·25“?€>€¥s· ··—·r3;=   ..,,.. *;,,,..,,4.ms   ““,¢   v·=’     -·—i-
          .‘-.-. »         ·=r·    _,_,.__,.   _
            .·vv   »   _‘___ .    
e' /‘‘`. ‘ . - ..·.   T       be »*· ‘  ·‘  ~     ~~e.L, iv.  ..
- .,..-» ;       .2 .·--     .-,:*7***  #9 s we W .y...2i·;*£*»?é5·>~w»¤ 
            ‘ 4»  V i F   »»-»         .
Fig. 8.- Ground limestone should be applied uniformly. Parts of this field were
heavily limed, while other areas received little.
inalw unilliirni spivauliiiig a must, when the lielcls are small and (lil`-
liculi to e·<>x*¢·r with a li<·ax·y truck, and when light iiiaiiitcnanee appli-
<·ati 7 .
ll`ll(‘ \\’ll(‘l`(‘ lllll(‘ tlllll CI`()]`) gI`()\Vtl1 il1'C C()I1CC1'l1€(l. Tl](3 lUOSt ]_)I`Ollt21l)l€ '
])l'()C(’(llll`(‘ is to a,gQ2.5~;Ef».Q~gi.§§e}T;g—'?““>;{·¢E3g»;i§§;
e     ~..\. . v . .... M if -¥ t.t. ·   _,:    
    V , ‘ .       ¤`  "  ..,,;g;,¢·;Y‘7*‘-°  ..». » Y, p    ’
§&;*.¤§;é:t;m;_Zjg§_;., .,T,.,£<*ij  ` § •’ Fc   ~·  
  »¤.,   ~—~—   .   . · · .._, _ —        
    __~·    ·- il.? ’=.TZ# ' .... }  :4 ll   
  · · *   e»v  1 %:/R, ·
   *> __ _     _     ·_-»      
F Q        ·— ·     F   `A        M 
  FA` H I"  -`_?:— Xi , ~· *2 I ix ;A _ gr.    ..:_iv ., . E >, •f ",,¤.t;     H
P`-,/· <;..,· ..;>¢¤ ~·" · ~_ j»—»;\ —,.    Jggv  ,. "    ._.,.  
»•;m•· .»+·\>~» 4 J   . L `*° 4 .  ,   *~*•¢;,` ~?’°   ~¢ ·»
g,,,.>$_‘__   `§·§.;o..‘ ` 3   . 4   wa} . .  
"\&g,¤»zs if ’ F . {fi _,_ *tZ°Z·¤ i.¤},¤` . `*4    
git "     4 ‘ F ‘ - t *5** wcuw .~ .   ·
£}·;Q2» ¤ `$`#$$· , " — " ` _"?“ it F 4 V  =.·¤"`
Fig. 9.- Use of a hopper spreader drawn by a tractor is a good way to spread .
limestone evenly.
14

 the greater solubility of some substances (manganese and aluminum,
for instance), may be sufficient to result in a toxic effect 011 the grow-
ing plant. As the pI·I value of a soil is raised above neutrality, phos-
phorus, boron, zinc, manganese, and copper, all of which are esse11-
tial for plant growth, become less soluble, and therefore, less available
to plants. In addition to paying for extra lime, the farmer who ac-
tually overlimes may also have the expense of corrective treatments,
necessitated by the high pH attained.
An example of tl1e effects of too 1HllCl] lime and the resulting
fixation of zinc on corn yield is presented in Table 4. Zinc deficiency
symptoms appeared in the third-crop year after the limestone was
_ applied, but they were 11ot identified and diagnosed for several years.
The rate of zinc sulfate used i11 this trial has since been found to be
much more than actually needed. Rates of 12 to 15 pounds per acre
placed with the seed at planting time now appear to be sufficient.
Table 4.- The effect of zinc sulfate on the yield of corn grown on overlimed soil
i TT 7`reutment in uddifiori to N, P and K T; pH T Yield, Im/rf,
T- No li1ne No ZnSO_; 5.8 39.5
70 T/A lime No ZnSO_1 7.8 4.9
70 T/A lime 259 lb/A Z11SO_1 7.8 46.5
High pH values are especially troublesome 011 sandy soils. S11ch
soils are likely to contain only small amounts of essential lTll1lO1` ele-
ments, and the availability of these small amounts is greatly reduced
as the pH value goes up.
Two I]l€tll()(lS lllily be followed to overcome these shortages of
the essential elements which are induced by overliming. The first
and most L‘()IIllll()ll way is to apply tl1e (‘ll‘Ill(‘lltS which are deficient
beca11se of their low solubility at tl1e high pll. These must be applied
i11 a manner that will supply the (‘l(*lllOlltS to eacl1 crop, such as sweet
clover, alfalfa and corn, until the slow processes of llt1t\Il`C lower the
plil of the soil to the level at which the elements in the soil again
become soluble and available to the plants. The difficulty with this
method is the lack of easy methods to diagnose what is needed. _
how nmch should be used. and how to apply it before crop yields
have been drastically reduced. The procedures re<{nire;l for the de
termination of the quantity of the minor elements in the soil or in the
plant are not so short a11d simple as the determination of phosphorus
or potassium; special laboratory equipment is required.
‘ The second way to overcome shortages is to make a soil more
acid. particularly when growing blueberries and certain ornamental
plants. Sulfuric acid, iron and Llllllllllllllll sulfatcs, a11d powdered sulfur
15

 can he used. Sulfuric acid reacts quickly and is often cheap enough
for field application, hut is hazardous to handle. Iron and aluminum
sulfates are usually too costly, hut are often used in nurseries. Be-
cause of its relatively low cost, sulfur is the logical choice for use.
Sulfur is relatively slow in reacting because it must first he oxidized
by soil organisms to form sulfuric acid before it is available for rc-
action with the soil. llates of 800 to 1500 pounds per acre of ele-
mental sulfur are likely to he required on most silt loams to lower the
pll   to 1 unit. Sulfur should he hroadcast and mixed thoroughly
into the soil hy disking. Two to three warm months will he required
for the sulfur application to react.
Although the high buffering capacity of our soils helps prevent
overliming, farmers should not depend upon this. A good soil test is _
the hest guide to follow when determining the quantity of lime needed.
t`·»·»;»i~r.;tiyr· Extension \\'nrl< in !\lL!`ll`lllll1l'(‘ and Home Economics: College of Agriculture
and llmne Economies. University of Kentucky. and the United States Department nf A
.\gr1eultur¤-. cooperating. \\'illi:nn A, Sea}: Director. Issued in furtherance of the Acts of
\ln5 ll and June 30, 1914,
SNIA)-($2 -