xt7rxw47rj7k https://exploreuk.uky.edu/dips/xt7rxw47rj7k/data/mets.xml   Kentucky Agricultural Experiment Station. 1946 journals kaes_circulars_004_432 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. 432 text Circular (Kentucky Agricultural Experiment Station) n. 432 1946 2014 true xt7rxw47rj7k section xt7rxw47rj7k I   in Kentucky Agriculture i A  
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    Circular 432 V ¤
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    College of Agriculture and Home Economics I A
    Agricultural Extension Division ` _  
    THOMAS P. COOPER, Dean and Director V  
iv   .

‘ To M eet the potash Problem  _``,—
on Kentucky Farms . . .  
1. Use potash fertilizers on soils naturally deficient in   ,1l_ b 1
potash. If in doubt, make small plot tests on the } n‘nl yl
fields, and have chemical soil tests made.  _ com
` A · 2. Grow enough legumes in crop rotations to fix large ~*
amounts of nitrogen. Conserve and return to the soil .
as much as possible of the crop residues and manure.
Drag pastures at least twice a year to scatter manure '
dropped on them. Make field tests and chemical tests _ S
for need of additional potash. i V‘
3. For alfalfa in rotation on soils that do not supply  
enough potash for it, apply fertilizer potash for the i l
alfalfa. Don’t use manure on the alfalfa, for it retards y EVE
nitrogen fixation. Use manure on the nonlegume A any
crops in the rotation, and as far ahead of the legumes Q pla
as is practical. . Egl-
4. For high-priced crops like tobacco, if enough manure ._ to '
is not available, fertilize liberally with fertilizer ·  
potash along with other needed fertilizers, and care-   ` We
_ fully save and protect tobacco stalks for fertilizer. ls  
_ They are best applied about the time spring growth A ms:
of crops begins. fig?
[ 1mi
5. Keep the soil covered with grass or cover crops to é
prevent losses by leaching and erosion. l
coNTENrs l· tn
[ l
‘ an
, Residues with Cover Crop Help to Maintain Potash for Corn .......... 6 s __
Need for Additional Fertilizer Potash for Alfalfa .....i . .........,.... 7  
Manure-Limestone—Phosphate vs. Limestone-Phosphate ................ 8 __
Limestone-Phosphate-Potash vs. Limestone-Phosphate ................. 10 pig
Amount of Manure and Time of Application in Rotation ...,......,,.. 11 _
i— A
L I i

   I   A 
  i` I
  The Potash Problem in Kentucky Agriculture ·,  
~ I I
  By Gizoxcia Rosmtrsl I I-
F0   I
J A Potassium is one of the mineral elements required in large amount J
  by crops. The approximate content of potash2 in some of the crops ` i  
 ` commonly grown in Kentucky is as follows: A ` _
E2 Paundsof I I`. ,, ,
V Potash ’ A
. Corn, 50 bushels, including stalks ...................,...............,............ 50 V  
Wheat, 25 bushels, including straw ......,....................................... 35 · q A _A .
' Alfalfa hay, 1 ton ...................,...................,......,.........................,.,... 50 I  
A Clover hay, 1 ton .....l......i............i.........................».............i............ 40 · A A
A Lespedeza hay, 1 ton .................................................,.......,.............. 30 V
i Timothy hay, 1 ton ........................................................................o. 30 ` I
in Burley tobacco, 1000 pounds leaf and 600 pounds stalks ....,....... 55 ` I A
I Even though a soil may contain a large amount of potash, there is at '
X any one time only a small part of it in a form that can be used by   _
·· plants. It is very evident, therefore, from this fact and the above V
· figures, that unless much of the potash taken up by crops is returned . ,
A to the land, either in crop residues and manures or in fertilizer potash ,
Q (or both), there will soon be a potash deficiency which will reduce _»
  · yields of crops. This is the potash problem in Kentucky farming. It I
is brought on largely by the fact that such large quantities of crop A _ ·
· residues and farm manure are wasted on Kentucky farms, and it is ‘
aggravated by the fact that many farmers fail to recognize the great .,
I importance of potash in their soil-fertility problems.
  Munure and Crop Residues Contain Much Potush ` A.
  , By saving all possible crop residues and animal manure and re- .`
Page   Yllming them to the soil, and by using practices which prevent th€
3 l nutrients in the residues and manure from being wasted by leaching I I
4   and erosion, farmers can maintain supplies of available potash in their
l 6   soils that will greatly reduce the need for commercial-fertilizer potash. I I
6   For best yields on most farms, some fertilizer potash will be needed ·4
7   ‘ProEessor of Agronomy Emeritus.
g H ’The term "potash" is used in this circular instead of "potassium" because I
10 D0t¤sh" is the term generally used both in rhe fertilizer industry and by farmers.
11 Potash content of a soil or fertilizer is equal to 1.2 times the potassium content of it. K
3 s r I Y
~ I
I ` i ·

 ; 4 .  
i for some crops, because even with the most careful saving of crop resi-  yl {
’ dues and manure, not all the potash removed from the soil by crops l  that
can be returned.   Pot;
About nine-tenths of the potash in feed eaten by animals is con-   Seyit
tained in the urine and solid manure. Most of this potash can be   tili;
returned to the soil if the right methods are used in conserving the   as 1
p i manure produced. About two-thirds of the potash excreted by ani-   i:_- Cm}
mals is contained in the urine. Most of this is lost unless there is plenty   cou
of bedding to absorb the urine. Also, a large part of the potash in   Thi
the solid excrement is soluble in water and is lost if the manure is  v_ . my
exposed to rain before spreading. The wastage of farm manure in y
Kentucky is estimated at about 16 million dollars a year. Probably  y
not more than 60 percent of the fertilizer value of manure is utilized.  1} l. ¤b0
_ Stock should be fed and kept under cover except when they are on  3 bro
pasture, and the manure needs to be kept under cover until it is   will
spread. Pastures need to be dragged at least twice a year to scatter   fert
the dunghills and make the manure more effective.   be
Two-thirds to three-fourths of the potash of grain crops is in the   [hc
stalks and straw. These should always be returned to the soil, prefer-   " for
ably after being used as bedding for animals fed under cover.   deli
Tobacco stalks contain considerable amounts of potash. For each  it I the
1000 pounds of burley leaf there are about 600 pounds of sta1ks—and   Stag
_ this amount of stalks contains about 20 pounds of potash. Most of  
this potash is soluble in water and is soon lost when the stalks are   go;
exposed to rain. Loss of potash (and of nitrogen also) through   ma
improper care and use of tobacco stalks in Kentucky is enormous. Y has
  A soil
if; gui
Cropping Practices in Relation to Potash ». cm
Tobacco is a heavy feeder on potash. Unless heavy applications   tili
of manure are made, land for tobacco should be liberally fertilized ._ ist
with a fertilizer containing a high percentage of potash as well aS   ph;
of nitrogen and phosphorus.   seq
Hay crops, especially alfalfa, also are heavy feeders on potash.  is Yi€
- Too many farmers think that a good growth of a legume crop improves 4 leg
the soil even though the crop is harvested for hay and no manure is }_ SQV
returned. As a matter of fact, all hay crops deplete the soil of the ’ _ ml
mineral nutrients unless the manure produced from the hay is SYS- _ {Y0
tematically returned to the soil. ; ma
` l

  5 · 5
 if {  
H`   One ton of alfalfa contains about 50 pounds of potash. Alfalfa i Tl
PS   that yields 3 tons per acre per year for 5 years takes about 750 pounds of     V
  potash from the soil, per acre. No soil can stand such a drain without l
I1-   serious deficiencies appearing, unless the potash is returned in fer- . li '_ .
>€   tilizers or manure. Yet many farmers use a seeding of alfalfa for hay ~ .   '
1e   as long as the yields justify cutting; then they put the land in other T_  
li'   crops without replenishing the potash. The depletion of potash ac- y   -
FY   1 counts for many of the poor yields following several years of alfalfa. · · l
[fl   This is particularly true of tobacco following alfalfa, for tobacco _ ,  
ils  `- ‘ requires a large amount of potash in a short time. T   s
ly  y The best use of alfalfa is to sow grass with it and use it for hay T_ y T
d_   about 3 years and then turn it into pasture. When the pasture is   A
m  -V broken for cultivated crops manure should be used liberally, which ' .
is   will return considerable potash. lf the land is put back into alfalfa, ' ~
er   fertilizer potash should be applied, or at least a test with' potash should ·
  be made on small areas and if these small areas respond to potash Q
lc   the ·whole area should be top—dressed. The quick chemical tests I *.
ir-  »- for available potash may be made before seeding alfalfa. Potash _  
j  deficiency in alfalfa is indicated by white or yellowish dots around _
ch   the tips of the leaves, particularly the lower leaves. In advanced p
ld   stages of deficiency the lower leaves die and fall off. `
Of   T As previously stated, too many farmers think that when they grow r T ` — _ T
Y6 _f  good alfalfa, clover, and other legumes they improve the soil, even if the
lh ,[ T manure made from these crops is not returned to the land. Actually this ly'
'S‘   hastens the depletion of all mineral nutrients. It is true that on many V
  A soils a treatment with limestone and phosphate, and the growing of le-
vi; gumes following this treatment, greatly increases the yields of such l I
 r crops as corn, wheat, and tobacco for some time, without the use of fer- . .
ns X tilizer potash or the return of manure. The chief reason for this i
ed   is that on most of the depleted soils of the state, the need for calcium, T l
as if Ph0Sph0rus, and nitrogen limits crop growth before potash; COD- T
  · sequently a light draft has been made on the potash by low crop .
h.  it Yl€ldS, and when the soil is improved by the limestone-phosphate- ` ·
es ,— légumc combination there is usually enough available potash for ’
is   several large crops. Many farmers fail to realize that this practice ,
ht? ’ _ rapidly uses up the reserve of available potash and that they ShOL1ld, I
ys- g from the very beginning, conserve and return all crop residues and l
; manure, to prevent the deficiency. . ` .
5.. l
" l l
l` 3 -
l I

. Another practice that causes some loss of potash is the growing   of tl
i of lespedeza without grass seeded with it or without a winter cover   com
crop. VVhen the lespedeza dies in the fall it soon begins to decay,   and
forming acids which may combine with potash compounds in the   and
soil to form soluble potash compounds. Part of the soluble potash   stalk
then is leached out of the soil in underdrainage water. Grass or a  ’·’‘ `_ were
' grain cover crop with the lespedeza would use some of this potash  I bina
and prevent its loss. Such loss may also occur with red clover after I   acre
harvest if grass is not grown with it. For this reason grass should   pota
be sown with clover and other legumes to conserve not only potash  f_— tinu»
but nitrogen also. Lespedeza is grown so extensively in Kentucky   ferti
that it should be the state’s greatest soil-improving and conserving   than
crop, and it can be if grass and cover crops are always used with it _ V estir
K and the manure produced from it is properly conserved and used. 1 a "c
A Cover crops should follow all cultivated crops to prevent the loss Q 49.6
` of potash and nitrogen by leaching and erosion. . V busl
- _ _; pou:
Some Kentucky Experiments With Potush
Residues with cover crop help to mcintuin potash for com   NEG
Soils and crops workers at the College of Agriculture and Home  __ ‘
‘ Economics have long warned farmers that potash deficiencies would   Well
occur unless all crop residues and farm manure were carefully con-   abc.
served and returned to the soil. Experiments started many years    
ago show the results of such neglect. One of the earliest was on the ‘ _l
Experiment Station farm at Lexington, in what was called "Th€ L Soil
Renewed Experiments," reported in Kentucky Agricultural Experi-   xg]
ment Station Bulletin 331 (1932). Two sets of plots containing 10   bus
plots each were used. These plots had been used for fertilizer experi- `
IHCHIS from 1888 to 1898, during which time the land was poorly j;
drained and in a state of low productivity. The land was partially tilt-   _ alla
drained in 1891. Continuous cropping was used and no manure 01‘ .i·i - liu
residues were returned. From the end of the old experiments until ’ _ ;I_;_
‘ the renewed experiments were begun the land was in grass for pasture y my
A moderate amount of manure was applied to the pasture.   ger
In the old experiments, potash produced large increases in c01`1¤ l· wei
yield. When the experiments were renewed in 1914, corn was grown   be;
on both sets of plots without any fertilizer, and the average yields I hoi
. I.

   · ·—l 1 i;
  1 1
1g   of the two sets were the same (43.2 bushels per acre). After that 1 ii
er   corn was grown continuously on one set of plots without a cover crop { , _ ‘
y,   and with the cornstalks removed; on the other set a rotation of corn  
ie   and soybeans was used, with a cover crop each year, and the corn- 1 A.  
sh   stalks and soybean straw returned to the plots. Both sets of plots · .··`
a  '·'` i_ were fertilized at the same rate with single elements and various com- ly ._ 1,
sh  . ‘ binations. In the rotation, 7 crops of corn averaged 54.7 bushels per . ‘  
er   acre for all plots, with no increase from application of fertilizer ‘ V
ld   potash. For the same 7 years the average yield on the plots in con- . ·_ li.
sh   tinuous corn was 42.4 bushels per acre. On plots where complete by  
ky   fertilizer was used the yield averaged 4.0 bushels per acre higher · 1
ng   than where phosphate and nitrogen only were applied. It is inter- `
it _- esting that the yield on the plot in continuous corn fertilized with ,  
cd. 1 a "complete" fertilizer (460 pounds of approximately 5-5-18) was · .v N
>SS .1 49.6 bushels, while on unfertilized plots in the rotation it was 53.1 '
. V bushels. The soil of these plots contained from 23,000 to 26,000 .
_; pounds of potassium and 5,000 to 6,000 pounds of phosphorus per •`» A
  acre in 7 inches of soil.
  Need for additional fertilizer potash for alfalfa 1
nc   A fertilizer experiment was begun in 1911 on a highly phosphatic, i
dd *?’ well-drained soil on the Experiment Station farm. This soil contained ‘ ·   `
m_ ,1 about 28,000 pounds of potassium per acre in 7 inches of soil. From
MS 1 1911 to 1931 a rotation of corn, soybeans, wheat, and clover was used. ‘ 1
he Q The cornstalks, soybean straw, and wheat straw were returned to the
he soil except for the 1'irst 4 years. Use of fertilizer potash during the 1
¤_i_   period increased the yield of corn 1.0 bushel per acre; soybean seed (
10 in (16 crops), 0.8 bushel; 6 soybean hay crops, 239 pounds; wheat, 0.1 V '
n_i_   b¤She1; 13 clover crops, 319 pounds. · .
I-ly ; Beginning in 1932 the rotation was changed to corn, wheat, and
uc. € alfalfa for 2 years. Manure was applied for corn on all plots at the ` ~
Ol.   _` Tale of 8 tons per acre, ln this test the use of fertilizer potash iHCTe3Sed
ml , the yield of corn (7 crops) an average of 2.5 bushels per acre; wheat (7 ' . Q
lm ‘ Crops), 0.7 bushel; first-year alfalfa (14 cuttings), 294 pounds per cutting ,
g_ Per acre; and second-year alfalfa (13 cuttings), 151 pounds per cutting
E- P€1` 3Cre. The alfalfa was generally cut three times a year, but yields T
ml ° W€1`€ determined only on yields fairly free from weeds. There seemed to ` ‘ V
WH   be fully as much alfalfa in the weedy cuttings as in the cleaner cuttings, ( {
slds I however, and the 200 pounds of muriate of potash per acre applied ‘  
. l
( 1
1 1

when wheat was sown thus produced an increase of about 1,335 pounds   T
of alfalfa hay for the 6 cuttings in the 2 years it appeared in the   bush·
rotation. ·   than
Alfalfa requires so much potash (about 50 pounds per ton) that   mile
it cannot be grown long upon the same soil without causing a potash   were
. deficiency. In a rotation like this it is not advisable to apply enough   C
manure to meet the potash needs of all the crops, including alfalfa; to gai    like
do so would supply so much nitrogen that it would reduce the nitrogen   Yiéld
fixed by the alfalfa. Legumes do not fix nitrogen unless the supply   Thé
in the soil fails to meet their needs. In a rotation including alfalfa  
it is better to apply enough manure to meet the potash needs of the  
nonlegume crops and to apply fertilizer potash for the alfalfa just  
before seeding. It is best not to grow alfalfa for a long period on the   -—
· same soil, but rather to grow it in a rotation like the one just cited or to   mw
sow grass with it and harvest it for hay for about 3 years and then turn   lm
it into pasture. Excellent bluegrass pastures may be produced by this   Lime.
procedure almost anywhere that alfalfa can be grown. After th€   mm]
pasture has been grazed a few years, it may be used for a cultivated   Lime
crop for l or 2 years and then returned to alfalfa and grass. In this   mms]
way the whole farm may be converted to a grass-livestock type of   Mm
farming, the type that should be used in Kentucky wherever practical.   M-
M¤nure-limestone-phosphate vs. limestone-phosphate  
At the Mayfield Experiment Field in 1914 two sets of plots of four  
each were treated alike with limestone and phosphate. A rotation of   Tim
corn, soybeans, wheat, and a mixture of clover and other legumes and   Q
grasses for the fourth year was used through 1931, after which tht?    
rotation was corn, wheat, and 2 years of a mixture of legumes and   i
grasses (see Kentucky Agricultural Experiment Station Bulletin 397    
for details). The use of manure (applied for corn) on one set of plots  gy Man
and the return of crop residues on the other set was begun in 1916.   .._
After 1919 the use of crop residues was discontinued in order to com-  
pare the use of limestone, phosphate, and manure with the use of  if
l limestone and phosphate only. Alongside these plots was a set of pl0tS   OH
on which no limestone or phosphate was applied but to which Il’13.llUl`€   fill)
was applied. On both sets of plots on which manure was used it WHS  if- hm
applied in amounts equal to the weight of crops removed, except th€  ij ‘ def
wheat grain.   191*
\ ,

ds   The set of plots to which no manure was applied produced only 1 (L 1 1
1e   bushel of corn less per acre in the first round of the rotation (1914-17) J.
gi  than the set to which manure was applied, showing that there was g" Y
at T.  little difference in the original productivity. (Manure and crop residues -1
  were a lied onl in 1916-17 in this round of the rotation. L  
sh  ,i PP Y . _ _, .
gh  if Corn shows potash deficiency to a more marked degree in a rotation _1 ¤
  l _ _ _ ' il
to   like those used in this experiment, and wheat the least. The average _ 1 ., .
gh  gf; yields of crops on the three sets of plots through 1938 were as follows. 1 1 (
,1y  {;... The last period includes the years after the rotation was changed. ( ( fy
fa   ‘  ·
he   i 1
he  `f (Bushels per acre) (Pounds per acre) _ (
 ,_.   .  · _
to   First 9 Next 9 Last 5 First 8 Next 8 ,
 y · Treatment crops crops crops crops crops ‘ ‘
Iii   Manure )\ _ Manure 1
U5  Q}. Limestone ....... 40.7 52.7 50.2 Limestone ............. 3482 3603 ·
he   Phosphate I Phosphate (Q V.
ed   Limestone Limestone
lis   V Phosphate } ....... 36.3 39.2 32.7 Phosphate } ............. 3317 3330 _ A
Of  if Manure ........... 31.6 40.9 43.0 Manure ................ 2581 2991 '
 1.     . .
al.  i. ·
 if} _ .
  (Bushels per acre) (Pounds per acre) A
 r`     1
im  ‘ First ·1 Next *1 Last *1   S€°°¤d i
of   Tmatmmt crops crops crops First 7 Next 'I Last 5 year hay
    C1`0pS C1'0pS CTODS (6 crops)
nd   M_¤¤U1`€ Manure 1
he  1; Limestone ....... 18.6 25.8 21.9 Limestone   3673 4967 6000 4707 1
nd   Phosphate Phosphate 1
·   L. [ ' ·i
»97 in _p—_t P{QQ§;lj’a‘l; ) ....._. 17,1 21,1 iss     3417 3696 4408 3997
OES  _j1» 7
16  ._ Manure ......,___, 9.2 10,2 11,7 Manure ...... 1147 2566 3066 2950 ' 1
‘  J. ~——&-*7A.__;_.—. - _ -- - - .... . .
·m·   .
Ol   T 1 1 p
ots   O0 the plots receiving limestone and phosphate only, the yield of corn ·
ire   Yilpldly declined as compared with yields on those receiving manure, _
vas  Q. h}“€Sl0¤€, and phosphate, As the yields declined, symptoms of potash _ '
.1112   ~ deficiency develo ed in the corn. When otash deficienc occurs the 4
_ P P Y .
  lower corn blades turn brown at the tips and edges. As the deficiency 7 ‘ L
J.- [
 -.. 1 ~
 gl · I L
. S 1
` I

increases this condition extends toward the midribs, and leaves higher  
up on the stalks are affected. In extreme cases the lower_leaves die. _ 
In 1937 the manure—limestone-phosphate plot produced 52.6 bushels  
per acre, and the limestone-phosphate plot produced 29.3 bushels.  
When the corn was planted that year, part of the limestone-phosphate  {Y s
plot was liberally fertilized with potash, and on that part of the plot  —. .
. the yield was 52.1 bushels per acre. This is a most convincing example  
of the importance of conserving and using manure as a source of  
potash. In this experiment the amount of manure used was only two-  EQ.
thirds of the possible production of manure. On the average, 1%  
tons of manure are produced per ton of feed and bedding. All the  
manure cannot be accumulated in the barn because much of it is  
dropped on pasture. This can be made effective by dragging pastures  >
to scatter it. Q "
Limes|·one—ph¤sphcte-potash vs. limestone-phosphate  ‘-
In 1940 the limestone-phosphate plots of the foregoing experiment   suppl};
were divided and half of each was liberally fertilized with potash but no  -_ 0; fm
manure was used. The average acre-yields of corn for 1940-42 were as  _` ¤i**¤¤
follows:  ?‘ -
bu   need
Manure-limestone-phosphate plots ..... Q ........ . .....r.................... 57.1   will
· Limestonephosphate plots ...................................................... 41.2   and
Limestone-phosphate-potash plots .......................................... 49.4  jg. I-mm
Manure plots ........,........r................................................._.......... 51.2 -7  - The
These yields show two very important things — (1) the importance   ( [0 fc
of potash, and (2) that because of the deficiency of nitrogen where   (mg
manure or nitrogen fertilizers are not used, high yields of corn cannot   esgil Pwd
be produced even though potash is used liberally. Kentucky farmers   EVE
should beware of developing farming systems in which they will have   f S?
to depend upon large amounts of commercial nitrogen and potash. A Q- Cm
grass-livestock system of agriculture reduces to a minimum the need   - the
for purchase of potash and nitrogen. In grass-livestock farming such .7 mm
purchases are usually necessary only for crops of high acre-value, like   - A
· tobacco. On a few soils in the state that are naturally low in potash,   mi
fertilizer potash is needed for other crops also.   GPP
One fact that stands out in the results from the various experi-   e
ment fields is that even when manure equal to the weight of cr0p5   lil  
taken from the land is returned, the manure will not meet the potash f` ‘hll'
¤ .

 . 1 .
  tl l 1»
  ii ;   *
 ¤t* T l
Fr   ‘ aus:-nets or conn nan ACRE A i `*
   Qi so 40 so so   _ y e
It   MAN unatinesrona-   ' l   ,
*1**   tnmesromz- nnos PHATE-i   ’ ‘ l' .  
Of   P•-OTS   . i r
’°‘   — ’ ..
Mi  5 uMesroNe— pnosnnzm:     ’ · - T l * Q T
IS  i ‘ . ~
  MANURE MTS   l l
  Corn Yields in Experiments at Mayfield, 1940-42
gm   For high yields, corn must have plenty of potash. Manure returned to the land ,‘, .
no   supplies. not only the needed potash, hut nitrogen also. A grass-livestock system '
; . of farming therefore reduces to a mrnrmum the need for purchase of potash and
35  ` nitrogen. 4 ` "
 Qi needs of all the crops in the rotation indefinitely. For some time it T i
  will meet the needs of the corn crop (to which it is usually applied) V _ .
  and the wheat crop following, but the clover and grass crops farthest · ` ·
  removed from the application will sooner or later show a deficiency. _ V
;V The only way to put off theltime when this deficiency will-occur is {
me   K0 feed animals under shelter and save and use the manure, and tO
are   drag the pastures to scatter manure. When livestock Cannot be On
my i" Pasture that furnishes worth-while grazing, they should be kept under l I
ers   C0ver. The barnyard is a source of great loss of manure on many farms. .
we   If saving and use of manure does not meet the needs for potash, then `
A   fertilizer potash should be used. The manure and crop residues from
md Q, V the increased yields should be carefully saved and utilized so as to I ‘
[ch §V recover as much as possible of the purchased potash.
are f . . i y
ShV ‘· Am0¤l1l‘ of manure and time of »
AV application in rotation
gri-   · In l92O an eiiperirnent was begun on the Experiment Station farm _
gps i Qu Lexington to test the effect of different rates of manure applied at  
ish V" different times in the rotation. The plow layer (7 inches) of soil for . l
E. l
l 1 ,

 l 12
° this experiment contained approximately 4,700 pounds of phosphorus   ing CN
and 24,000 pounds of potassium per acre. A 3-year rotation of corn, j gmam
wheat, and clover was used. Manure was used at the rates of 4, 6,   clover-
and 8 tons per acre, on duplicate plots, on corn; on wheat at the same   Th
rates in the late fall or early spring, through 1933; at the same rates   R largt
on the young clover soon after the wheat was harvested, through 1933.  _ Clover,
g . From 1933 to 1938 the manure for these plots was applied on the  1 appliel
wheat in late winter or early spring just before growth began. Thus   did m
each rate was used on four different plots in each of the three series,   Com, i
giving twelve replications in the three series of plots for the rotation.  ‘ the CO
In each series there were six check plots to which no manure was  l may hy
applied. Yields on these unmanured plots averaged 51.3 bushels of  s a he
corn, 23.8 bushels of wheat, and 3,375 pounds of clover hay per acre.   glgho
Where manure was applied on the corn the increases in yield over  
the unmanured check plots averaged as follows:   licgs;
Increase per Acre   Be
Corn Wheat Clover hay Q , each I
bu bu lb ’·· ·
4 tons manure per acre ................................ 13.1) 2.8) 346   Phcd
6 tons manure per acre ................................ 14.2 4.0 611   Poms}
8 tons manure per acre ................................ 15.6 4.3 832  . all P1'
Where the manure was applied on wheat or clover but not on corn,  
- the increases were as follows:   F
Increase per Acre  
Corn Wheat Clover hay  
(bu) (bu) (lb)  
4 tons manure per acre ................................ 9.5 3.2 792  
6 tons manure per acre ................................ 9.1 4.0 910  
8stons manure per acre ................................ 8.8 4.5 926   It
  the y:
Wheat yields were thus about the same whether the manure WQS   when
applied on the corn or on the wheat or clover. Increases in com   Of mf
yields were definitely greater where the manure was applied on th€   Sfatec
. corn; and increases in yields of clover hay averaged about 300 p0und5   mil  
greater where the manure was applied on the wheat or clover.   im]:
These lower yields of corn following application of manure Oil gg.   
wheat or clover than following applications on corn are very signifr  L fanhl
cant. As corn in the rotation followed clover, supposedly a soil-build·  

T 13 .   l
 - i ·· 1
ms   ing crop, it might beI expected that the corn would benefit from the VI *1
ml   greater growth of clover where the manure was applied on wheat or  
6,   clover.   T
mf? _  The writer believes the explanation is as follows: The clover had · I II a
les   a larger use of potash where manure was applied on the wheat or - _I[ ·.
33   clover, and therefore the yields of clover were higher. But the manure __ 1 ,
the  I applied to wheat or clover supplied so much nitrogen that the clover I VI   .
}us   did not fix as much nitrogen as where the manure was applied to T - » I
les' {  corn, and consequently there was not so much nitrogen available to _ fg
OIL I,  the corn as if the manure had been applied for the corn. Also, there I   _
va;   may have been less potash available to the corn where the manure was 4 . I I ».
1;  . applied to the wheat and clover—but this is of secondary importance, . ‘
QC;   as shown by the following experiments in which there was little in- ( -   (
  crease in corn for potash the first three years where 8 tons of manure  
  had been used on wheat and clover. II
_   Beginning in 1939, manure was discontinued on all plots, and .
ray   each plot, including check plots, was divided in half and potash ap- •I~ ,'
  plied liberally to one half when corn was planted. The first year (
  potash was used, the average yields of corn were as follows (includes , I "
  all plots): '
 k ‘ ‘
rm,   Buhels of Corn per Acre I
  F0rmer.marture No potash Potash Increase Tar I I ' .
  Treatment applied applied potash `
  None .......................r.............. 38.3 48.1 9.8 I ' I
6  gt 4 tons ...................................... 47.8 53.0 5.2
  6 tons ...................................... 51.4 54.2 2.8
  8 tons ..................,................... 56.8 57.6 0.8 4
  It is interesting to note that where 8 tons of manure had been used ·I
  the yield without potash (56.8) was much greater than with potash
was   Where no manure had been used (48.1). This shows the importance ` ·
gm   of manure as a source of nitrogen as well as of potash. It should be
the   Stated that there is seldom a season at Lexington when the distribu- .
nds  if ;_` @011 of rainfall is sufficient to produce the maximum crop that the I.
  fertility of the soil will permit, although the total rainfall may be
On   high- IH 1942 when there was well-distributed rainfall the yield was i
lm   Practically double the yield of 1939, although the crop was 3 years I I y
ild_   farther away from the last application of m&I1UI`€. A -  
  I ;
  I I

Theaverage increases of corn foripotash the first 3 years after the  C signifie
use of manure was discontinued were: » ~   second
,   1940,
_ _ V V _ Bushels per Am   seeded
` . ””°"’“°)   second
Where no manure was used previously ............,.. , ................ 6.5 ‘ 
.  _. heavy.
Where 4 tons manure was used previously .,,.....................,. 3.3 5·  th r
l Where 6 tons manure was used previously ....... . .................. V 2.3   O €
WhereV8 tons manure was used previously .........,......i...,.. T. 1.3   Crops ‘
' ,  Q for th
_  jg nitro
Approximately ll tons of manure could have been produced from  T; mbui
the crops grown on the plots treated with 8 tons. In a good livestock   if the
s stem of farmin the extra 3 tons of manure would have been dro ed  if
Y h g PP   cover
on t e pasture.  
 J Ur
The increase for otash the first ear as com ared with the first  
P Y P  V and a
3 years’ average looks a little strange, but the following facts are  ga manu:
i l   for pc
NO ~¤ POTASH ;§;£;£;S;£;E;§;i      
, MANURE POTASH   xi  Th<>S<
· ` · i V _·_._._•_·_»_»_-_._·_·_·_._.Q._•j•j.j._sf.f.f.f.‘.'.‘.‘.'.'.‘.‘.'. I J   
, *i'6°$$6Z6Z+Z•I•Z•Z•Z•Z•Z•Z•X•Z•Z•Zi  ii for pr
4 T<>~S {NQ ,"?°T’·‘$" T §?E§§;:;:;:§:;:§:§:£:§:§:§:§:§:£:E:§   i. W.,
MANURE ~ . @:3:§:§:§:§:§:§:§:§;§:§:§:§:Q:}:§:§:Q:{zi:{:§:Q:i:§:Q:ititititig;2;Z;2;§;§;§:§:§;§:§:  
T POTASH ¤E=E=E=€=E=E=€=$=E=$=i=§=£=&=E:2:2:2:2=i=i=&