Front Cover
 Title Page
 Table of Contents
 Land preparation
 Seed and varieties
 Commercial hybrid seed production...
 Diseases and insects of corn
 Sweet corn production in Flori...

Title: Florida corn
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00086043/00001
 Material Information
Title: Florida corn
Series Title: Florida corn.
Physical Description: xiv, 181-440 p. : illus. (part col.) map. ; 23 cm.
Language: English
Creator: Komarek, E. V
Publisher: State of Florida, Dept. of Agriculture
Place of Publication: Tallahassee
Publication Date: 1951
Subject: Corn -- Florida   ( lcsh )
Corn -- Diseases and pests   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
General Note: "A reprint of chapters VII through chapter XVI of the original volume by the same title and author."
 Record Information
Bibliographic ID: UF00086043
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 01574557
lccn - 52062451

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Page i
        Page ii
    Table of Contents
        Page iii
        Page iv
        Page v
        Page vi
        Page vii
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        Page ix
        Page x
        Page xi
        Page xii
        Page xiii
        Page xiv
        Page xv
        Page xvi
    Land preparation
        Page 181
        Page 182
        Page 183
        Page 184
        Page 185
        Page 186
        Page 187
    Seed and varieties
        Page 188
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    Commercial hybrid seed production in Florida
        Page 354
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    Diseases and insects of corn
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    Sweet corn production in Florida
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Full Text

~~i - a,


A reprint of Chapters VII through Chapter XVI of the
original volume by the same title and author.
(See note under Table of Contents.)

Compiled by
Greenwood Forms

State of Florida
Department of Agriculture
Nathan Mayo, Commissioner

The Florida Department of Agriculture has brought
together for the use and interest of Florida farmers and
those interested in Florida's rapidly expanding livestock
industry and agriculture reliable, thorough, and up to
date information on Corn. Grateful acknowledgment is
made to the various authors, the experiment stations of
the states of Florida, Georgia, Indiana, Iowa and Illinois,
the Corn Industries Research Foundation, the American
Seedsmen's Corn Annual, and others for the reprinting
of their material and inclusion in this Corn encyclopedia;
also to E. V. Komarek, Greenwood Farms, for compiling
the material and writing additional sections where needed
to make the book complete.


NOTE: The original comprehensive volume "Florida Corn"
compiled Ny E. V. Komarek contained twenty-two chapters.
Reprinted in this booklet are only nine chapters, Chapters VII
through XVI, containing that material which is considered the
most important in the actual cultivation of the crop. The page
numbers appearing in this booklet are the same as those in
the original volume and they begin with page 181, Chapter VII,
and run continuously through page 446, which is the end of
Chapter XVI.

F orew ord .................................................................. .............................................................. v

In trod u action ............................................................................... ......................................... v ii

Chapter VII
Land Preparation ............................ .................. .............................. 181

Chapter VIII
P la n tin g ................................................................................................................................. 1 8 5

Chapter IX
Seed and V varieties ....................................................... ............................. 188

Chapter X
F fertilization ....................................................................... ........................................ 2 2 9

Chapter XI
C u ltiv a tin g ........................................................................................................................ 2 6 7
Chapter XII
H a rv estin g ........................................................................................................................ 2 99
Chapter XIII
S tora g e ................................................................................... ......................... ........... 3 0 3

Chapter XIV
Commercial Hybrid Seed Production in Florida ........................ 354

Chapter XV
Diseases and Insects of Corn .................................................................... 423
Chapter XVI
Sweet Corn Production in Florida ............................ .............................. 444


IT IS THE PURPOSE of the State Department of Agriculture to urge
the farmers of Florida to raise more and better corn. For too long,
the farmers of Florida and other sections of the deep South have
had to depend on Iowa and other corn belt states to supply suffi-
cient corn for home needs.
Every farmer in Florida should, with proper planting, fertiliza-
tion, and cultivation, produce enough high quality corn for his
own use as well as to help supply a ready market. Our Experiment
Stations will supply you with information for the asking and your
county agent will help you with your problems. He will advise
the best fertilizer to use and the correct quantity for your type of
soils. Corn breeders are developing new hybrids for the deep South,
which will increase yields from 30 per cent to 50 per cent, depend-
ing on the type of soil and the amount of fertilizer.
Florida is becoming widely known as a beef cattle state, and
yet beef unless it is corn fed is not generally adapted to the trade.
Consequently carloads upon carloads of Florida cattle are shipped
into other regions for fattening. Potentially Florida could grow
enough corn to fatten a considerable proportion of its grass-fed
beef for its own use. Today the higher grades and cuts of beef are
imported from the midwest packing plants. It would seem that
the emphasis on the development of improved pastures and better
bred cattle has now reached a point where livestock people should
begin to think of making the beef grown on such pastures the
kind of meat that people in Florida want to eat. There is tremen-
dous room for expansion of Florida corn production for this
purpose alone, with wide benefits for all concerned. With the
increased curtailment and acreages of such so-called cash crops
as cotton, it would seem that the expansion of corn acreage in
Florida would be a natural addition to its livestock program.
Although Florida imports considerable milk it has a sizeable dairy
industry of its own, which again has to exist on imported food-
stuffs, among which corn plays a big part. The South produces
much of the high proteins, such as cottonseed and peanut meals,
used in livestock feeds. If it produced a proportionate amount of
corn, it would become much more self sufficient and dairying costs
would be materially lowered.
Assistant Commissioner of Agriculture


Acreage in Corn
* 5,000 acres-Field corn
+ 500 acres-Sweet corn


CORN IS TRULY A SYMBOL of America's greatness. Throughout its
history it has been the one crop that in its success or failure
touched in some manner the welfare of everyone in all the Amer-
icas. To the early Americans, the Indians from the ancient Mayas
and Incas onward, it has been the staff of life.
Those intrepid early American pioneers would have reached
these shores and accomplished little had it not been for this New
World cereal. The written record of their early struggles against
famine and hardship is filled with many examples of when this
"wonder grain" saved them time and again. And though corn is
truly a southern plant, more native to Florida than to the midwest,
its ready adaptation first by Indians, then by the white man, to
a strange climate of short seasons perhaps made the rapid western
expansion of this nation possible. Striking it is, the Indian had
made more gains in the development of this plant from its wild
beginning (in the Andes of Peru) than the white man, including
even the development of Hybrid corn. Corn was a finished grain
much as we know it today when the first white man gazed upon it.
Its greatness today is attested by the following simple facts, for
it still is the staff of life in all the Americas, including this nation.
The value of its annual harvest far exceeds that of any other agri-
cultural crop. This country's corn fields produce each year more
wealth than its metal mines, its coal fields, or its oil wells. One
corn crop exceeds in dollar value the combined net worth of three
of the largest manufacturing corporations of the United States.
More farmers raise corn than any other crop; more land is planted
with its seed; and corn is raised in every state in the Union, as
well as in every Central and South American country.
Close to one-twelfth of all of the United States farm land is
utilized for its culture; one out of every four acres in crops pro-
duces corn. Wheat, hay and cotton stumble along far behind. In
Florida alone over half of the acreage in field and truck crops is
planted to corn; nearly twice the acreage of citrus and other orchard
crops is used for this cereal each year. Florida on the basis of its
acreage, on the importance to its welfare, and as a foundation for
its live stock industry of beef cattle, dairy, and poultry, is just as
truly a corn state as the midwestern states. Historically and botan-
ically it is even more so; late frosts in spring and early frosts in
fall do not so limit the growing season as to jeopardize the crop.
The average yield for the state of Iowa dropped from 60 bushels


Value1 of Corn Crop, With Comparisons, 1946
Item Value
Thous. dollars
Corn for all purposes ................................. 4,628,685
Wheat, all kinds .......... ... .................... 2,213,443
;Lay, all kinds ............................... ........... 1,688,458
Cotton and cottonseed .............................. 1,662,343
Oats .................................................. 1,194,893

Coal, bituminous and Pennsylvania anthracite2 .......... 2,101,280
Petroleum2 .................. ...................... 2,093,300
Metallic products (iron, ferro-alloys, copper, aluminum,
zinc, gold, silver, etc.)2 ................................ 1.975,000
Net worth of General Motors Corporation, United States
Steel Corporation, and E. I. DuPont de Nemours Co. .... 3,733,000
1. The value of the agricultural crops was obtained by multiplying the season average
farm price by the estimates of total production as described, by States, and adding
the results to get a total for the United States. The value of the mineral products
was generally at the point of production.
2. Data are for 1945.
3. Net worth is the sum of capital stock (less treasury stock) and surplus.
Source: United States Department of Agriculture and Interior, and National Industrial
Conference Board.
per acre in 1946, a bumper corn year, to 36 bushels average in 1947
when the shortened season did not allow corn to make.
Growing and production of corn in Florida has been much neg-
lected largely because of the idea that corn was a midwestern plant
-which it is not. Corn is more truly a southern plant, as is evi-
denced both by its origin and its length of growing season. The
production of this cereal in the Corn Belt is hampered by late
frost in the spring and early frost in the fall, and corn grows in
the midwest only because it has been adapted to that climate by
man-first the Indian, then the white man. Few farmers realize
that the world record in corn production according to the U. S.
Department of Agriculture is held in the South; a yield of 239 bu.
per acre made in South Carolina in 1889. In recent years there has
been much interest in the midwest corn belt trying to produce
300 bushel yields. The highest yield thus far attained has been
226 bu. per acre in Iowa. In a recent article in the Country Gentle-
man by a midwestern corn breeder it was stated "As a matter of
fact I wouldn't be surprised if the first 300 bushel yield didn't
come from the South instead of the Corn Belt."
Records kept on 4-H Club and FFA contests in Florida and
neighboring Georgia have conclusively proved that yields of 50
to 60 bu. per acre can be very profitably made on much of our land.
The average of over 2000 contestants in the years 1946, 1947 and
1948 has been between 50 and 60 bu. per acre in every county a
contest was conducted. Top yields ranged as high as 115.2 bu.
per acre. Most of these yields were made without the use of the
newest Florida Hybrids, such as Dixie 18. Likewise further proof

that profitable yields can be made in Florida, if any such is
needed, are the records of the Experiment Stations at Gainesville
and Quincy, Fla. Their yield and records on various hybrid corns
consistently produced more than 50 bu. per acre. Even with its
average low yield per acre for the state, the cost of producing an
acre of corn is less in the South than in Iowa. According to the
U. S. Department of Agriculture, Bureau of Economics, the cost
of producing an acre of corn in Iowa is $37.64; in the South it is
$30.00. (Agri. Statistics 1946.)
It is natural to question why the average corn yields in Florida
are low. There are several major reasons, but perhaps the most
outstanding is the need for crop rotation. Somehow the idea has
been developed that our soils are inferior and not productive of
corn. Much of this has been caused because farmers have been
growing corn in many instances on the same land year in and year
out for a decade or more. In this connection it is most interesting
to note the yields taken on the Morrow plots located at Urbana,
Illinois in the heart of the black prairie soils of central Illinois.
The plot that has been continuously in corn for 70 years now grows
an average of only 16 bu. per acre. The plot that has been in crop
rotation with corn on that plot only once in every three years has
today a yield of 100 bu. per acre. Is it surprising then that our
yields in Florida are low when even on the best soils of the mid-
west corn cannot be grown following corn year after year without
reduction in yield?
In recent years there have been many striking examples in the
Deep South of the rapidity with which our soils recover their corn
productive capacity when such lands grow corn only once in three
years, and the other two years grow cover or less depleting crops.
It should not be impossible for the northern one-third of Florida
to average 35 to 50 bu. per acre yields. The soils in the northern
half of the state in times past have been intensely farmed and
depleted of certain essential elements, as well as humus. They are
easily built back up to produce high yields by the use of sufficient
amounts of nitrogen, phosphorus and potassium, but in recent
years much evidence has been accumulated to show the absolute
need of certain minor elements for certain crops. Florida can take
credit in being the pioneer in first pointing out on a practical
scale the necessity of using such minor elements as zinc on corn.
It is tragic to say the least that even though the initial studies on
zinc deficiency on corn were made several years ago, farmers as
a whole have not utilized the information. On many soils the ap-
plication of 10 to 20 pounds of zinc sulphate to the acre can be the
difference between high and low yields. In the production of hybrid

seed corn yields have been increased from 7 to 10 per cent by such
small amounts of zinc sulphate as 10 pounds per acre.
Another factor in low yields in the state has been the lack of
the use of cover crops until the last few years. We are fortunate
in having several crops which can be used to build up the organic
matter as well as nitrogen in our soils. Among them are blue lupine,
first released by the Florida Experiment Station, crotolaria, cow-
peas, velvet beans, etc., all of which are treated fully in the chapter
under Cover Crops.
Still another factor of considerable importance causing low yields
of corn is due to improper planting. Farmers are very careless of
their planting machinery, particularly of tractor planters, and in
this humid climate in combination with the use of fertilizer such
machinery deteriorates very rapidly under the best of care. When
such machinery is not in perfect working order it is impossible for
a farmer to get good stands. Without good stands of at least 6,000
to 10,000 stalks to the acre he cannot make good yields. If a rotation
of cover crops and other crops is followed along with sufficient
fertilizer, corn should be planted no wider than 42 in. rows and
18 to 24 in. in the drill, depending on the variety and the soils.
In recent years there has been considerable interest throughout
what might be termed the Southern Corn Belt, of which Florida
is the southernmost state, in hybrid corn. As early as 1933 a hybrid
was developed for Florida, Florida W-l, but was not used widely
because of production difficulties in the producing of high grade
seed. In the last few years it has been demonstrated emphatically
that both high producing hybrids, as well as highest quality hybrid
seed, can be produced in north Florida and the neighboring sec-
tion of Georgia. Even though the interest in hybrid corn began
early in the state, it has been only in the very recent past that
sufficient funds have been available for the necessary research
and testing that needs to be done to produce real hybrid corn.
Research in corn has been neglected as a crop because of such cash
crops as cotton, peanuts, tobacco, citrus, and livestock, all of which
have organized associations furthering their use as well as research.
Corn has remained the Orphan Annie of agricultural research,
even though its total acreage in the state is greater than all other
cultivated crops combined. It might be pointed out that out of 144
members of the Agricultural Experiment Station, less than a
baker's dozen of individuals have been vitally concerned with corn
and its culture. This is no reflection in any way on the station,
but simply points out that the pressure in agricultural research
has been so great on the so-called cash crops, that the crop that
used more land in Florida than any other has been neglected.
The possibilities of hybrid corn production in Florida today


seems unlimited. In 1948 Dixie 18, a yellow hybrid, which perhaps
is a forerunner of what is to come, was developed by the coordinated
work of the Southern Experiment Stations. Of the four inbred
lines used all four inbred lines were isolated years ago and
have lain idle in the various experiment stations until just recently.
Two of the lines came from Florida, one from Georgia, and one
from Louisiana. They were combined at the Coastal Plains Experi-
ment Station by Dr. Wayne Freeman at Tifton. This hybrid has
given an average increase in yield of 20 per cent in Florida, and
at Gainesville in tests under the direction of Dr. Fred Hull, the
originator of two of the lines, and Florida W-1 the Dixie 18 out-
yielded everything else in the test by over 40 per cent in 1948.
Thus in summary, by the use of high grade hybrid seed corn of
adapted varieties, proper crop rotation, proper fertilization, proper
planting, and proper cultivation, Florida can produce a great
share of the corn for its own needs and for its livestock industries.

All Corn
Sweet Corn 1944
County 1948-49 Crop Year
Alachua ......... 300 1,456
Baker ........... 100 334
Bay ............. 86
Bradford ........ 600 667
Brevard ......... 50 7
Broward ......... 50 26
Calhoun ......... 14,370
Charlotte ........ 24
Citrus ........... 3,828
Clay ........ .. 2,014
Collier .......... 8
Columbia ........ 550 27,884
Dade ............ 350 4
DeSoto .......... 330
Dixie ............ 1,883
Duval ........... 2,273
Escambia ........ 13,043
Flagler .......... 2,237
Franklin ........ 3
Gadsden ........ 38,430
Gilchrist ........ 9,779
Glades .......... 500 702
Gulf ... ... .. 701
Hamilton ........ 100 23,974
Hardee .......... 300 2,439
Hendry ......... 1
Hernando ....... 2,370
Highlands ....... 16
Hillsborough ..... 2,350 6,922
Holmes .......... 33,640
Indian River ..... 1
Jackson ......... 76,997
Jefferson ........ 34,529
Lafayette ....... 13,319
Ag. Econ., Exp. Sta.-1,000

Sweet Cor
County 1948-49
Lake ............ 300
Lee ............. 200
Leon ............
Levy ............ 25
Liberty ..........
Madison ........
Manatee ......... 100
Marion .......... 700
Nassau ..........
Okaloosa ........
Okeechobee ......
Orange .......... 1,700
Osceola .........
Palm Beach ..... 4,400
Pasco ...........
Pinellas .......
Polk .......... 400
Putnam .......
Santa Rosa ......
Sarasota ........ 75
Seminole ........ 900
St. Johns .......
St. Lucie ........ 150
Sumter ..........
Suwannee ....... 75
Taylor ..........
Union ........... 200
Volusia ...... ..
Wakulla .........
W alton ..........
Washington .....

All Corn
n 1944
Crop Year





Uses of Co
Feed and Seed:
Home Use:

rn in Florida
7,190,000 bushels
6,114,000 bushels
348,000 bushels
698,000 bushels

oL tr

Beef Cattle .........
Dairy Cattle ........
H ogs ...............
Chickens ...........

1,065,000 head
140,000 head
536,000 head
2,616,000 head

against 6,114,000 bu.


Florida Acreages in Field and Truck Crops
Corn .............. 733,000
Peanuts ........... 354,000
Truck ............. 223,800
Watermelons ...... 39,000
Cotton ............ 23,000
Tobacco ........... 21,900

Is Florida a Citrus or Corn State?
(1946) Cultivated Acreage in Florida, Including Citrus




4'j ,0. 00,.. -

.- .~ p ., cO .t i E r.. T. LL. P' TE COTTON 1)BACCO
in CL. T Ru; ME .LONS

Corn (For Grain): Estimated Cost of Production, by Selected States and Groups of States, 1939-451

State or group Net cost per acre, including rent
1939 1940 1941 1942 1943 1944 1945
Eastern: Dollars Dollars Dollars Dollars Dollars Dollars Dollars
North2 .................................... 22.50 23.15 25.45 30.97 36.46 40.02 42.80
South .................................... 15.45 16.26 17.70 21.25 26.11 30.00 31.96
Ohio, Indiana, Michigan, Wisconsin, and Min- 24.69 24.73 27.74 33.60 38.46 40.37 42.09
nesota ....................................
Illinois and Iowa ............................. 22.12 22.47 24.98 30.49 34.87 37.64 38.16
Missouri and Nebraska ....................... 14.36 15.57 16.52 21.63 25.68 29.72 29.61
. Kansas, South Dakota, and North Dakota ...... 12.89 13.24 14.67 19.28 22.56 25.94 26.85
Southwestern4 ............................... 13.97 14.46 15.82 19.17 22.22 25.03 26.78
W estern5 .................................... 14.59 13.68 15.23 20.28 24.13 26.64 27.15 ,
United States ........................... 18.77 19.22 21.07 25 89 30.32 33.57 35.00
1. The cost figures are based on average-per-acre yields of corn for grain, and on prevailing cost rates for labor, farm power, ma-
terials, equipment, and land rent.
2. Includes the 6 New England States, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, West Virginia, Kentucky,
and Trnncssee.
3. Includes North Carolina, South Carolina, Georgia, Florida, Alabama, and Mississippi.
4. Includes Arkansas, Louisiana, Oklahoma, and Texas.
5. Includes Montana, Idaho, Wyoming, Colorado, New Mexico, Arizona, Utah, Nevada, Washington, Oregon, and California.
Source: United States Department of Agriculture, Washington, D. C.

NOTE: The following reprinted Chapters VII through
XVI carry the same page numbers, 181 through 446,
which appeared in the original printing of the compre-
hensive volume.


No TRUER STATEMENT has ever been made than that half the corn
crop is in preparing the seed bed. Corn, and particularly hybrid
corn, with its vigorous root and large root systems needs soil of
good tilth in which to grow. Without entering into any contro-
versies regarding the use of the mold board plow vs. other tillage
implements, there are three different implements used in pre-
paring the seed bed for profitable corn production. One is the
mold board plow, now usually tractor mounted, the other the disc
tiller and a bush and bog or cutting harrow. All three of these
have their place in preparing good seed beds in various soils.
Objections to the turn plow is that it turns trash and leaves in a
layer several inches below the surface, so that in dry weather such
air pockets dry out the soil. Because of its speed the disc tiller
has largely supplanted the mold board plow. The tiller turns the
soil on edge, leaving the organic matter or cover crop or crop
residue inter-leaved between the various furrow slices. These
are in units of three on up to as much as ten discs pulled by
tractor. The third type, a bush and bog harrow, is commonly
used on very sandy soils where it is not necessary to break land
very deep because of the open and porous nature of the soil, and
on such soils apparently gives satisfactory results.
The first step in preparing a seed bed should be the breaking of
the land by one of the foregoing implements. If the land to be
used has a cover crop or other organic matter such as crop resi-
due, some implement such as a cover crop cutter, bush cutter or
disc harrow should be used to break it up before breaking. By
doing this the organic matter is more completely incorporated in
the soil and will make a much better environment for the roots
of the corn plant. Land should be broken at least two or three
weeks before planting, and in the case of heavy cover crops at
least a month or more. In turning such green cover crops as blue
lupine the writer has seen considerable damage done to stands,
and consequently poor yields of corn, because the cover crop was
not turned early enough to allow it to partially decompose and
become incorporated in the soil before planting.


Middlebuster plow


Bush and bog harrow

_~- -- '. ...^

Tractor mounted turn plow

..~~nZ "'' ''
'` ''

~.s -

51:~ ": r
~kC '''

~& 71


Tractor gang plow

Spike-tooth harrow

"~'L1Tui ..E*1L

Springtooth harrow



Smoothing harrow


JUST AHEAD OF PLANTING the land should be harrowed smooth
with a tandem disc harrow to make a very smooth and level seed
bed, and as most farmers in north Florida are mechanized or be-
coming so, remarks on planting are for tractor equipment. The
seed bed should be very smooth so that the planting equipment
can function properly and give good stands. The next step is the
actual planting, and on various soils, methods differ somewhat
but in general in north Florida it is best to plant in a deep fur-
row, and on the average tractor planter, a middle buster (at
least 16 in.) should be used. The furrow should be at least 6 to
7 in. deep, the planter and fertilizer follows right behind. The
equipment should be so adjusted that sufficient soil is placed upon
the seed after it is planted. If the seed corn is not covered suffi-
ciently, damage will be experienced to stands by birds and rodents.
In the looser, loamy soils of north Florida corn should be covered
at least 2 to 3 in. deep.
There are many reasons for planting corn in a deep furrow
in this region, some of which are; weed control-Because of the
heavy rainfall and high humidity weeds grow constantly most of
the year; For better root systems-by planting in a deep furrow

.% h *
'V'; *,
1 .,' '.1'* I. *. * .

Equipment for planting in water



the corn roots are down, and as the soil is worked to the plant,
the roots are below the surface of the soil and can withstand
dry weather or drought much more effectively. The writer has
seen many attempts to grow corn on a bed or flat, like in the
midwest, and all have uniformly failed. Where corn is planted
on the level with the top of the ground it is nearly impossible

Planting hybrid seed corn


to keep the drill free of weeds. By planting down in a deep fur-
row, corn as soon as it is a few inches high can be worked and
the soil can be trickled into the furrow enough to cover the weeds
in the drill.
Plants Per Acre

Width of Row

Spacing in Row

Plants per acre

Corn planter with middle buster

~ -o



It should be needless to say that only seed corn of high quality and
of adapted varieties should be used. Farmers have not taken the
needed care and frequently have poor crops because of germination
of seed with as low a germination as 50 per cent, or because they
have seed corn that is not adapted to their region. This is par-
ticularly true of hybrid corns, for middle western varieties are
not adapted to Florida, and every farmer should constantly check
with his experiment station and county agent to be sure of the
newest varieties adapted to his farm. The seed should have a
germination of above 80%, or preferably above 90%, and it
should be sized into at least two flat grades or two round grades
so that it can be properly planted with machinery. If corn is not
sized properly, it is nearly impossible to get even and uniform
stands. Enough seed should be used to give at least 7,000 to 10,000
stalks per acre. Normally this would run from 10 to 15 acres to
each bushel of seed corn.



Corn is grown in Florida primarily for grain production, al-
though small acreages are harvested as silage, and as roasting
ears for Northern markets. In the northern half of Florida corn,
as the principal grain crop, occupies a large proportion of the
acreage of cultivated land. Most of the crop is fed to livestock on
the farms where it is produced.
The climate of the corn growing region of Florida is generally
warm. Annual rainfall is 50 to 60 inches, most of which occurs
in June, July, and August. Rains in April and May are infrequent
and periods of two weeks or longer without rain occur nearly
every year in June and July. Such periods may be preceded and
followed by periods of almost daily rainfall.

The various soil types are found more often in their lighter
phases. Bacteria and other micro-organisms work almost continu-
ously throughout the year to destroy accumulations of vegetative
materials or humus in the soil. Light soils with low humus content
dry out quickly in dry periods. Soluble plant foods are rapidly
leached from them in rainy periods.
Destructive field insects and diseases over-winter easily and
find a long corn growing season in which they may work. Weevils
and other insects which attack the mature grain, and ear-rot
disease organisms, as well, are favored by a period of four to six
weeks of warm, rainy weather after the corn is fully mature.
The corn which is mature in July must stand in the field until
dry weather in September makes crib storage safe. Weevils may
continue working in the crib through most of the mild winter.
Under conditions just described, Florida corn yields have
averaged about 10 bushels per acre for the past 10 years. The
average yield in the main corn belt states is about 30 bushels for
the same period. Most of the corn grown in Florida is interplanted
with peanuts, velvet beans, or cowpeas. It has been estimated
that the average acre of Florida corn should be credited with
about 500 pounds of peanuts or its equivalent in addition to the
10 bushels of corn. Nevertheless, corn yields in Florida are too
low. They may be increased by: (1) improved seed; (2) fertili-
zers; (3) better crop management practices; and (4) better soil
management practices.
The least expensive means of increasing corn yields is fre-
quently the use of improved seed. Improved seed corn is the main
theme of this bulletin, which reports results of variety tests and
breeding work done by the Florida Agricultural Experiment
Stations at Gainesville and Quincy in recent years. Results pre-
sented here apply more directly to the northern half of Florida
where most of the field corn is grown.

Corn Varieties and Hybrids
Scope of Corn Yield Tests
Yield tests with corn varieties have been conducted at
Gainesville each year since 1924 and at Quincy nearly every year
since 1927 by the Florida Agricultural Experiment Stations.
Many additional tests were run with farmers and county agents
in the period from 1928 to 1933. These latter tests were distributed
over the entire state, but most of them were in the northern half

where more corn is grown. Corn yield tests have also been con-
ducted by the Everglades Experiment Station at Belle Glade,
but no detailed summary of the results of those tests is included

Many varieties and farmers' strains of corn from Florida
and neighboring states have been included in the trials from time
to time. A few varieties from distant states and foreign countries
have also been included. Many have been discontinued because
of mediocre or poor performance. A few new varieties and new
hybrids have been tested only in the last few years. The total
number of corn varieties and hybrids entered in Experiment
Station trials since 1924 is approximately 100.

Plan of Corn Yield Tests

Nearly all entries in the State Experiment Station yield tests
have been varieties and hybrids of which seed was on the market
or available in commercial quantities. A new stock of seed was
obtained each year from the breeder or seed merchant. Most
entries have been included only at Gainesville for one or two
years before being entered in other tests. Many were discon-
tinued after this preliminary test at the main station because
they were obviously unsatisfactory.
Every test was located on the most uniform land available.
All entries in one test were planted on the same date and given
the same fertilizer and cultural treatment throughout. Tests in
cooperation with farmers and county agents were fertilized and
cultivated according to the farmers' regular practices. In most
eases the farmer's own seed corn was included as an additional
entry in the test on his farm.

Tests at Gainesville and Quincy for each of the past three
years have consisted of six separate plats of each variety and
hybrid entry. Earlier tests on the Experiment Station farms
consisted of three and four plats of each entry each year.
Tests on private farms consisted of only a single plat of
each kind of corn but were located on six or more farms over
the region each year. It is hardly possible to obtain consistent
results with less than three plats of each entry for a single year;
nor is it possible to obtain a satisfactory measure of a variety in
less than three years. Comparisons of crop yields made on ad-
jacent areas with no repetition are often very misleading because
of hidden differences in soil fertility.


Records have been taken on yield of sound corn in every test.
Additional records on weevily and rotten ears, lodging of the
stalk, number of ears per plant, average weight of ears, days from
planting to silking, shelling percent, height of plant, cob color,
etc., have been kept with many of the tests. Test plats were
usually harvested in September at the normal time except at
Gainesville, where harvest has been delayed from one to three
months each year. Delayed harvest allows more severe insect,
disease, and weather damage to develop and thus provides more
critical comparisons. Some years when weevil infestation was
light in August, a small amount of corn badly infested with
weevils was strewn in the field to provide a more satisfactory
determination of weevil resistance. Percent of weevily ears
recorded at Gainesville is therefore much higher than in other
tests or on farms in the Gainesville region.

Results of Early Corn Yield Tests
Results of corn yield tests have been released currently in
mimeographed circulars from the Experiment Station since 1924.
Tabular summaries of results for the past five years are pre-
sented in the following section. They seem to provide ample
support for recommendations given in this bulletin. Neverthe-
less, the records of earlier tests provided a wider perspective
view of the entire situation than that found in recent work.
They thus served very well to guide the breeding work de-
scribed in later sections.
Corn varieties included in earlier performance test fall mostly
into two distinct groups. In the first group are native varieties
and farmers' strains which have mostly one-eared plants. They
are somewhat resistant to weevil infestation and damage in that
the ear is covered with a long, heavy, tight husk, and kernels
are smooth dent to flint in type. The second group includes
prolific varieties from neighboring states. These varieties have
shorter and looser husks. Kernels are soft in texture and medium
to rough dent. Percent of weevily ears range much higher in
prolific varieties than in Florida varieties and the damage to
an infested ear of soft corn is much greater than to an infested
ear of hard corn, as every Florida corn grower knows. However,
yields of prolific varieties, almost without exception, ranged from
15 to 30 percent above yields of the best native varieties. It was
obvious from these results that the main objective in corn
breeding work should be a combination of prolificacy and high
yield with weevil resistance.

Comparisons of results from tests on private farms under
prevailing farm conditions with results obtained on the Experi-
ment Station farms under somewhat different conditions show:
1. Ranking of variety yields on private farms is generally
the same as on Experiment Station farms.
2. Ranking of variety yields in the northern half of the state
is generally the same in all sections of that region. There are
some exceptions.
3. Ranking of variety yields in the southern half of Florida,
particularly on muck lands, is likely to be quite different from
that found in the northern half of the state.
4. Ranking of variety yields on river and lake bottom muck
lands in upper penisular Florida is generally the same as on the
farm of the Everglades Experiment Station at Belle Glade.

Description of Corn Varieties and Hybrids
Descriptions and photographs of corn varieties and hybrids
which are of particular interest in Florida at the present time
are presented here. These descriptions must not be considered
exact, for the development of a corn plant depends on growing
conditions fully as much as on breeding. Following descriptions
have been written to summarize and briefly amplify those records.

Fla. W-1 (Florida White Hybrid No. 1)
Origin.-This is a first generation double cross hybrid of four
inbred lines of corn developed by the Florida Experiment Station.
It is the only hybrid corn that the Florida Experiment Station
has released for commercial use.
Characteristics.-Prolific, two ears on nearly every stalk, up
to 20 percent 3-eared stalks at Gainesville; highest yielding corn
in variety tests at Gainesville and Quincy, 43 percent gain over
Farmer Composite; long, tight husks, smooth dent kernel type,
weevil resistance equal to that of Farmer Composite; strong root
system; tall, slender stalk; white seed; 50 percent red cobs, 50
percent white cobs; shelling percent by weight 81.5; 79 pounds
slip-shucked corn shell one bushel.



Fig. 1.-Fla. W-l. Upper, entire yield of
16-hill plat; 28 not weevily, 2 weevily, 5
rotten ears. Lower left, show sample of 10
ears slip-shucked, 10 ears clean shucked.
Lower right, typical plant.



I' jt i j
i! 4
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)$2 s)'.J ;Bs



Fig. 2.-Florident Yellow. Upper, entire
yield of 16-hill plat; 25 not weevily, 2
weevily, 4 rotten ears. Lower left, show
sample of 10 ears slip-shucked and 10 ears
clean shucked. Lower right, typical plant.


Florident Yellow
Origin.-Bred by Florida Experiment Station.
First released for commercial use in 1941.
Characteristics.-Two-eared; highest yielding yellow variety
in tests at Gainesville and Quincy, 20 percent gain over Farmer
Composite; long, tight husks on most ears, smooth or slightly

Fig. 3. Flori-
dent White. Up-
per, entire yield

not weevily, 10
weevily, 5 rotten
ears. Left, show
sample of 10 ears
slip-shucked and
10 ears clean

rough dent kern-
el t yp e, weevil
resistance ap-
midway between.
Farmer Compo-
site and the well
known variety
Whatley Prolif-

ic; very strong root system and stalk, least lodging of any entry
in tests at Gainesville and Quincy, this statement strongly support-
ed by observations on fields of Florident corn, yellow seed; 85 per-


Fig. 4. Farmer Compo-
site. Upper, random sample
of ears from Florida farms
i in 1938; 41 white, 4 yellow,
1 red. Center, entire yield
of 16-hill plat; 12 not
weevily, 3 weevily, no rot-
ten ears. Corn produced
From seed shown above.
Lower, typical plant.
cent red cobs; 15 perce'lt
white cobs; shellinlt per-
\ cent by weight 79.5; 85
pounds slip-shucked corn
shell one bushel.
Florident White
Origin.-Same as Flori-
-" jgdent Yellow. First re-
leased for commercial
use in 1939.
cally same as Florident
SYellow, except seed color
is white.

Farmer Composite
Origin.-A representative, mixed (not interbred) sample of
corn grown on Flori a farms in the past five years. Much of the
corn grown by Florida farmers has been in their possession for a
long time and is not known by varietal names. There is some vari-
ation in details, but the general types are similar. This corn may
be known as Florida Old Field corn. A search through early his-
tories of Florida has discovered many references to corn growing,
but no mention of type. In recent years at least there have been
introductions of such varieties as Whatley Prolific, Hastings Pro-
lific, Cuban Yellow Flint, and early white varieties grown for
roasting ears. The Farmer Composite contains some of these varie-
ties and :ome slight mixtures of them with the Old Field corn.

i "I 'i"
.ir3tV j 0

Fig. 5.-McIntosh, Show sample of 10 ears slip-shucked and 10 ears
clean shucked.

Characteristics.-Florida Old Field corn is mostly one-eared,
medium yield; long, heavy, tight husks, smooth to slightly rough
dent kernel type, weevil resistance good; medium root system,
strong stalk, likely to lodge in summer and fall storms; white
seed; Florida Old Field corn has white cobs, but about 15 percent
red cobs appeared in the Farmer Composite; shelling percent of
Farmer Composite by weight 81.5; 89 pounds slip-shucked corn
shell one-bushel.
Origin.-The Reverend W. H. McIntosh, Bonifay, Florida, be-
gan growing this corn in 1908. He has selected seed from the field
with special attention to plant type.
Characteristics.-90 percent 2-eared, 10 percent 1-eared plants,
yield gain over Farmer Composite 11 percent at Gainesville, 5
percent at Quincy; long, tight husks, smooth dent kernel type,
weevil resistance equal to that of Farmer Composite; medium
root system, medium stalk, more likely to lodge than Farmer
Composite; white seed; white cob; shelling percent by weight
83; 83 pounds slip-shucked corn shell one bushel.
Origin.-W. R. DuBose, Lake Butler, Florida, and his father
have grown this variety for many years. Seed has been selected
from two-eared plants in the field since 1934.
Characteristics.-45 percent 2-eared, 55 percent 1-eared plants,
yield equal to Farmer Composite; long, heavy, tight husks,
smooth dent kernel type, weevil resistance slightly better than
in Farmer Composite; medium root system, medium stalk, lodges
more than Farmer Composite; white seed; white cob; shelling per-
cent by weight 81; 89 pounds slip-shucked corn shell one bushel.

b -

Fig. 6.-DuBose. Show sample.


Fg. 7. Cuban Yellow
Flint. Shou sample and
typical plant.

Cuban Yellow Flint
), i,ii* -- Nllltiv i :',r11 11

Fil h i t I f-ii ir 111 i 1i 1 tl iri,
F ,it-r,.la i ary till-a T' ',
Cubi,, 'l Yllir. Flint and
Spl eai l '1i;ll.i. Fl"iijt \li rt
n-,tjainp, tr,.,u th,. Kilgr.,re'
,:..l C.. pJcidl ', Plant (.'ity,
F l,:ria l ,|r,,..,!.1 (_'ilan
F lint 1%;-, .,itni ei.l 'fr.i
WV. H. Th.I-S..,I. Llo.y,1.

C*-l t '- /,l ,1.1 i 21r lt ,:1 .

,are,.l i l,,nt-., v ,:l,.I.d -li.iht-
Iy linrim Ftrieii r t.''.Iiip. I
r. iir I i ir, *i tP ii -i.%
,It,-; in `1, tiht, hav mr,,
\ r.vy t..il" h11 l11 isk tri.: llint
ki,: lnei ty l,,*, i *,. ll II i -t.
I. Ik -ll V ,v i[) ,ll. s I.1 il,

F ar in r 'li: ,sit ; 1.11 -
,ii1111 ti ,i u* k ri..'.t ,Mstirll
and -tilk, un-r, like-ly t,.i
,.l0ig thlin Fariit, r ',ilm -

Io|it|( 1 e :]-. 1..* li, 1.\ h i 1'li1 i ',_



Fig. 8.- Whatley Prolific.
Upper, entire yield of 16-hill
plat; 17 not weevily, 16 wee-
vily, 3 rotten ears. Lower,
typical plant.

yellow; 5 percent red, 95
percent white cobs; ma-
tures 3 to 5 days earlier
than native Florida corn;
shelling percent by weight
80; 87 pounds slip-shucked
corn shell one bushel.

Whatley Prolific
Origin. Seed obtained
from Whatley Brothers,
Helena, Georgia.
Characteristics. Two-
eared, yield gain over Far-
mer Composite 17 percent
at Gainesville, 24 percent
at Quincy; husks often
short and loose, rough dent
kernel type, weevil resist-
ance much below Farmer






Composite, but best of out-of-state prolific varieties; medium root
system and stalk, more likely to lodge than Farmer Composite;
while seed, red cob; shelling percent by weight 81; 86 pounds slip-
shucked corn shell one bushel.

Wood Hybrid Golden Prolific

Fig. 9.-Wood Hybrid Golden Prolific. Entire yield of 16-hill plat;
5 not weevily, 22 weevily, and 1 rotten ears.

Origin.-Seed obtained from T. W. Wood and Sons, Richmond,
Characteristics.-75 percent 2-eared, 25 percent 1-eared plants,
yield gain over Farmer Composite 10 percent; short, loose husks,
smooth or slightly rough dent type kernels, weevil resistance poor;
medium root system, short, small stalk, slightly more likely to
lodge than Farmer Composite; yellow seed; white cob; shelling
percent by weight 79; 80 pounds slip-shucked corn shell one
Corn Belt Hybrid Corn
Origin.-Seed lots of various pedigrees obtained from com-
mercial seed companies and Experiment Stations of states in the
main corn belt.
Characteristics.-One-eared, yields 10 to 50 percent below
Farmer Composite; short husks, dent type kernels, weevil re-

distance very poor; medium root system, small slender plants.
Very poorly suited for planting in Florida.

Characteristics of a Good Utility Type of Corn
A good variety of field corn
\ for general use in Florida:
1. Produces high yields.
2. Has strong resistance to
Damage by insects, diseases, and
adverse weather.
S3. Has good quality and ap-
4. Is well suited to common
feeding practices.
Many characteristics of the
corn plant which determine the
above points are inter-depend-
ent. Some of them are antagon-
istic, making compromises nec-
essary in choosing an ideal type.
It is thus hardly possible to dis-
cuss each characteristic separate-
ly. The main characteristic of a
good utility type are listed first,
l with brief discussions of what
may be controversial points giv-
en afterwards.

Fig. 10.--Typical plant of an
Iowa double cross hybrid corn
grown at Gainesville, Florida. The
ear projects through the husk

Characteristics of a good ulti-
ty type of field corn in Florida
1. Two ears of equal size on
each plant, with no third ear.
2. Ears large, strongly at-
tached, hanging down when ma-
3. No evidence of disease on
plant or ear.
4. Husks long, heavy and
tight at the tip.
5. Stalk medium height,


6. Root system extensive, many branches.
7. Kernels of smooth dent type.
8. Husked ear with 14 to 18 straight rows of kernels, cylin-
drical (not tapering) in shape.
Corn yield tests in the Southeastern United States have
consistently shown a marked gain in yield for prolific varieties
over one-eared varieties. Most of the gain is between one-eared
and two-eared types. A third ear does not provide much addi-
tional advantage except where total yields are exceptionally high.
Yield tests at Gainesville and Quincy with several hundred hy-
brids ranging from one-eared
to four-eared types have sup-
ported the above statements in
S general. Some of the highest
yields were obtained from two-
eared hybrids.
SProlific corn (Figure 11) is
S objectionable because of the
Sk greater difficulty of handling a
larger number of smaller ears.
Small ear size does not provide
the best appearance. The differ-
\ ence in ear size between one-
A; eared and two-eared corn is
S roughly illustrated in Figure 12.
Where ear-worm infestations
arre likely to be heavy, fewer
and larger ears are desirable to
reduce total worm damage, be-
cause only one ear-worm devel-
ops on the tip of one ear. On the
SL other hand, husk extension to
Reduce damage by both ear-
worms and weevils is more easi-
ly obtained with a larger num-
_4 ber of smaller ears.
When all factors are consid-
ered, two-eared corn seems to
b'e the more suitable type for
average farm conditions in
Fig. 11.-A prolific corn plant The two good sized ears should
with seven ears. be strongly attached to the



Fig. 12.-Comparison of ear size of two-eared corn (top row) and
one-eared corn (bottom row).

stalk to prevent dropping off before harvest. They should be
hung low on the stalk and on opposite sides to obtain balance.
The shank should have sufficient length and elasticity to allow
the mature ear to droop or hang down to avoid catching rain
water and thus avoid ear rot.
A tight husk extension of two inches or more beyond the
tip of the ear often prevents infestation by weevils in the field
from the time when corn is mature in July until it is harvested
in September. This protection is continued in storage of slip-
shucked or snapped corn. Ear-worms usually enter the ear of
corn through the silk channel at the tip of the ear. The ear-
worm moth prefers to lay eggs on corn silk. Where husk ex-
tension is long, the ear-worm feeds on corn silk and eats its way
down to the ear. It is often full-sized, or nearly so, ready to cut
through the husk, and drop to the ground for pupation by the
time it reaches the ear of long-husked corn. With short-husked

.r r


corn the young ear-worm begins eating on the kernels as soon
as it has hatched.
It is much more difficult to obtain maximum development of
ear size and yield with long-husked than with short-husked corn.
Husk extension and ear size are antagonistic in some degree.
Nevertheless, a tight husk extension of two inches or more beyond
the ear of corn is necessary to provide adequate protection against
insect damage in Florida.
The corn plant which has a strong, sturdy stalk and an ex-
tensive root system is presumably better able to produce well
developed ears. In Florida the crop must be kept off of the
ground in the field through six to eight weeks of warm rainy
weather after it is mature. Frequently a heavy crop of velvet
bean vines must also be supported by the corn stalk. A strong
stalk, supported by a strong root system, and resistant to rotting
long after maturity is thus necessary.
All classes of corn from rough dent, which is quite soft, to
true flint, which is very hard, are grown in Florida, but smooth
dent, which is a medium type, is most common. Weevil damage
is usually more severe on the softer types, although weevils
do live in the flintiest of corn. Some classes of livestock are not
able to utilize flint corn efficiently unless it is ground before
feeding. Here again a compromise is made in choosing the medium
hard smooth dent for the general utility type.
Most fancy points which have been stressed in show card scor-
ing of ear corn have little or nothing to do with utility. Straight,
even rows of kernels make for finer appearance. A thick ear with
20 or more rows of kernels dries out slowly and is more likely
to rot than a more slender and longer ear. A sma'l cob with a
deep covering of kernels is usually considered an indication of
high shelling percent. Great importance is frequently attached
to shelling percent. However, records on many varieties of corn
in tests conducted by the Florida Experiment Station in past
years show no appreciable differences in shelling percent by
weight. The average shelling percent for all varieties is approxi-
mately 81 percent.
Corn Improvement
For many years the only known method of improving corn
was selection of the best appearing ears each year to seed the
next crop. As a result of work done by agricultural experiment
stations and similar agencies during the past 50 years, hybrid
corn has recently become very popular, especially in the main
corn belt states. In those states corn improvement now means
simply the development of better hybrids.

In Florida hybrid corn is still in the experimental stage.
Results shown herein indicate that adapted hybrid corn may be
more profitably grown than ordinary varieties under many con-
ditions found in the state. Nevertheless, under some conditions
ordinary varieties of corn are likely to be grown for many years
yet to come. Breeding work with corn being done by the Florida
Experiment Station includes development of new hybrids and
further improvement of the Florident varieties by methods com-
monly recommended for the improvement of ordinary varieties
of corn.
The two methods of breeding are described below after brief
discussions of the reproduction process and methods of controlling
pollination in corn.

Reproduction in Corn
Some knowledge of the reproductive process in corn and how
it compares with reproductive processes in other plants is neces-
sary for a full understanding of the various breeding practices.
Reproduction in plants by true seeds seems to be fundamentally
the same sexual process as is found in the higher animals. The
essential feature is a union of two especially prepared germ cells,
the egg and sperm, to form the fertilized egg, which by repeated
cell divisions grows and becomes a new plant. Egg cells are
formed in female organs of the flower. Sperm cells are formed
within pollen grains in male organs of the flower. When a pollen
grain is lodged on the receptive stigma or female part of the
flower, a small tube grows from the pollen grain into the stigma
and down to the ovary. The sperm cell passes along the pollen
tube to the egg. A single strand of corn silk, the receptive part
of the female corn flower, with pollen grains and pollen tubes
is shown highly magnified in Figure 13.
Many plants have both female and male organs within the
same flower, while others have only one sex on a single plant.
In the latter instance each plant has either all male flowers or
all female flowers. Corn is intermediate with female flowers on
the ear shoot and male flowers on the tassel, Figure 14. Both sexes
are found on the same plant but at separate locations.
Pollen may fertilize the same flower in which it was produced,
or another flower on the same plant. In either case the process
is known as self-fertilization or self-pollination. When pollen
fertilizes a flower on some other plant the process is called cross-
pollination. Corn pollen is light and dry. It floats easily in the
air and may be carried long distances by wind.. Corn pollen is
also carried by bees and other insects which collect it for food.


Corn is mostly cross-pollinated
as are some other species, under
ordinary field conditions more
than 90 percent of the pollen
functioning on the silks of a
corn plant coming from other
surrounding plants. Peanuts,
oats, wheat, and some other
plants are largely self-pollinat-
ed. Flowers of these plants con- !
tain both female and male or-
gans and are usually fertilized
by their own pollen. In the pea- f
nut there is less than 1 percent
of cross-pollination. Intermedi- i
ate types are grain sorghnms
and alfalfa, in which self- and Fig. 13.-Single strand of corn
cross-pollinations occur with silk and grains of pollen; tiny
tubes have grown out of the
about the same frequency. pollen grains into small hairs
It is clear that a high degree on the silk. Magnified 500 times.
of cross-pollination or cross-
breeding such as is the rule with corn will result in a broad an-
cestry. All seeds on one ear of corn have the same mother plant
but many sires are represented in surrounding plants. Continu-
ation of cross-pollination leads to variability rather than uni-
formity in hereditary makeup. If the seeds of a single ear of
corn are sown in a separate row, the resulting plants will be of
various types. If, however, the seeds of a single peanut plant are
sown in a separate row, the plants will appear nearly identical
in type. This uniformity in the latter instance is attributed to the
close breeding practice of the peanut which causes its ancestry
to be very narrow, only one ancestor to each generation. A corn
plant, on the other hand, is likely to have an increasing number
of different ancestors to each preceding generation-two par-
ents, four grandparents, eight great-grandparents, etc.
With each cycle of sexual reproduction there is a reshuffling
or reassortment of the hereditary factors which determine plant
type. If ancestry is narrow because of close breeding, there is
not much diversity among the hereditary factors and the reshuf-
fling occurring with sexual reproduction does not lead to much
variability. If ancestry is broad and cross-breeding is the rule,
as in the corn plant, there is much diversity of hereditary factors.
A new and wide array of types appears every generation. Uni-
formity of superior type has been obtained by the plant breeder




Fig. 14. Above, branch of 'i rs
corn tassel, the male flower -
head. Flowers on upper part of '1
branch opened and shed pollen 57
preceding day, mid-third flow-
ers open and shedding pollen.
lower third flowers will open
next day. Right, ear shoot of
corn, the female flower head .
with husks removed. Eacl,
strand of silk is attached to a
single female flower.

with cotton, rye, and sunflowers by artificially enforced close
breeding. Close breeding which is in fact inbree:ling hls been
found to weaken corn plants to the extent that it must be care-
fully avoided or circumvented.
Many plants are propagated from vegetative buds found on
stem cuttings, tubers, bulbs, ccrms, etc. The process involved
here in each case is non-sexual. There is no reshuffling of heredi-
tary factors. Progeny from a mother plant by vegetative propa-
gation are identical in hereditary makeup, regardless of the
breadth of ancestry back of the mother plant. Where vegetative
propagation is possible the plant breeder's job is greatly simpli-
fled. It is only necessary to find a superior plant. The identical
t pe may then be reproduced at will and in quantity. Vegetative
propagation of corn is unfortunately not possible by any means
known at present.



Fig. 15.-Hand pollination of corn. Left, ear shoot bagged day before silks appeared; silks now visible inside bag,
protected from pollen; tassel bagged to collect pollen. Center, pollen is dusted onto the silks first day after bagging
tassel, one to seven days after bagging ear shoot. Right, as soon as pollen is poured on the silks the ear shoot is
covered to prevent out-pollination; the bag is left over the ear until harvest time.

Control of Pollination With Corn
Control of pollination in corn may be done by hand or in
isolated plots. The process of hand pollination as practiced at
the Florida Experiment Station is shown in Figure 15. A white
glassine or parchment paper bag is pulled down over the ear
shoot before any silks have appeared and become pollinated.
Usually about two inches of the husk is cut off with a sharp
knife to hasten emergency of all of the silks. When silk has
emerged on the second day or later it may be seen through the
partially transparent bag. A suitable tassel which has begun to
shed pollen is then covered with a large bag made of heavy
brown paper. Note the tassel branch in Figure 14 upper; the
flowers near the tip had shed pollen the previous day, those at
the middle were shedding when photographed, and those on the
lower end of the branch would probably shed pollen the following
day. The bag is folded over and held tightly at the base of the
tassel with a paper clip. Any time the following day, in the ab-
sence of moisture from rain or dew, the pollen plant is pulled
over part way, the bag loosened and the tassel shaken lightly in
the bag. The bag, with the mouth kept closed as tight as possible,
is then carried to the silks. The operation of hand pollination
is shown in Figure 15 center. After pollen is poured over the
silks, the pollen-bag is clipped over the ear and around the stalk
to prevent out-pollination. In practice, removing the shoot bag,
dumping the pollen, and covering again with the pollen bag are
done in rapid succession to avoid contamination with stray
pollen likely to be floating in the air. By this method about
10,000 ear shoots are pollinated each year at the Florida Station
by three men working through a period of six weeks with two or
three extra helpers in the mid two weeks rush period.
Pollination control on a more extensive scale is done in iso-
lated detasseling plots. This method is used mostly for the pur-
pose of producing single and double cross seed in commercial
production of hybrid seed corn. Only one pollen parent may be
used in a plot, but there may be many seed parents. The pollen
parent is planted in every third, fourth, or fifth row in the field
and seed parents in the rows between. Tassels are pulled from
the seed plants before they shed pollen-all pollen in the field
then comes from the one pollen or sire parent strain. Tassels
must be pulled every day for a period of a week to 10 days.
Finally, suckers and a few late plants in the seed rows may be
broken off or topped with a knife to complete the job. Detassel-
ing plots should be separated from other growing corn, including
sweet corn, by at least one-eight mile (40 rods). Barriers of

trees are desirable. A few extra rows of the pollen parents on each
side of the plot, especially the windward side, will be valuable
in preventing out-pollination because of the greater supply of
the right pollen. A plentiful supply of the right pollen in both
hand work and in detasseling plots is always the best safeguard
against out-pollination.

Improvement of Open-Pollinated Corn Varieties
Various methods of improving corn varieties or developing
new varieties of improved type have been tried in agricultural
experiment stations in the period beginning about 1890. By 1920
or 1925 it was generally agreed that none of the newer methods
had produced substantially better corn than had the old practice
of mass selection.
Mass selection involves simply selection of better appearing
ears or plants to supply seed for the next planting. Selected ears
are shelled and mixed en masse, hence the name mass selection.
The breeding stock is kept as pure as possible by avoiding mix-
tures with stray pollen from other kinds of corn. Mass selection
has been frequently preceded by an intentional or accidental cross
of two or more different types of corn.
Some notable Florida corn varieties developed by mass se-
lection are DuBose, McIntosh, Tisdale, Smith, Blitch Red Cob,
Kilgore Red Cob Prolific, Wilson Yellow Dent, Petree Gold
Standard, and Erck Yellow Flint. New additions to the list are
Florident White and Florident Yellow. Both Florident varieties
came from a single foundation stock which was made up on
the Experiment Station farm at Gainesville in 1932 and 1933. A
number of test crosses of inbred lines and varieties with Whatley
Prolific were grown under comparable conditions and four of
the better ones were chosen for inclusion with Whatley in the
new variety. Two were the varieties Cuban Yellow Flint and
Wilson Yellow Dent, and two were inbred lines, one of which
(5-27) came directly from Wilson Yellow Dent. The other inbred
line (B12-8-4) came from an outcross in Whatley Prolific but was
yellow flint type. Each of the four crosses was separately crossed
back to Whatley Prolific in 1933 and seeds of the four back-
crosses were mixed mechanically to form the foundation stock
of Florident. Florident ancestry is theoretically 78 percent What-
ley Prolific, with the other 22 percent coming mostly from Cuban
Yellow Flint and Wilson Yellow Dent.
The Florident stock was planted on the North Florida Ex-
periment Station farm at Quincy in 1934 in an isolated plot. It
has been grown there every year to the present time with


mass selection of seed in the field each fall. Main points of se-
lection have been: (1) Two large ears of equal size on each plant
with no third ear (both ears used for seed); (2) strong, stocky
plants standing straight; (3) heavy, tight husks extending two
inches or more beyond the tip of the ear for protection against
weevils; (4) smooth, semi-flint kernel type; (5) freedom from
any indication of disease on the ear and stalk; (6) straight, even
rows of kernels and generally fine appearance of the ear.
The original stock of Florident was mixed yellow and white.
In the fall of 1936 the selected seed lot, after shelling, was sepa-
rated into three groups, white, pale yellow and strong yellow
kernels. White and strong yellow were planted separately in iso-
lated plots. The crop from white seed was mostly white with a
few pale yellow kernels. After another year for increase and fur-
ther selection the white lot was distributed as Florident White to
farmers and seedsmen in the spring of 1939. The first crop from
strong yellow seeds contained many white and pale yellow as well
as strong yellow kernels. Selection of strong yellow seeds for
planting was continued two additional years before Florident
Yellow was considered ready for distribution in 1941.
Whatley Prolific was used in the foundation Florident stock
because, as reported herein, it had been proven to be high yield-
ing over a wide range of corn growing conditions found in the
state. Furthermore, Whatley and varieties derived from Whatley
have made the best yield records in neighboring regions in the
states of Alabama, Georgia and South Carolina. Wilson Yellow
Dent, Cuban Yellow Flint, and the two inbred lines were in-
cluded primarily to bring in the best weevil resistance available.
They also provided yellow color. Inclusion of four strains besides
Whatley provided broad ancestry of the foundation stock. The
high proportion of Whatley ancestry (78 percent) was believed
desirable to increase chances of recovering the consistently high
yield performance of Whatley under various growing conditions.
Stating it another way, improvement of yield by mass selection
methods was thought to be more difficult than improvement of
weevil resistance, hence the larger proportion of high yield an-
cestry than of weevil resistant ancestary in the foundation stock.
Records on Florident corn at the Main and North Florida
Stations for the six years 1935-1940 show that yield began about
15 percent below that of Whatley. It rose rapidly at first, but the
increase has been less each year. The yield curve based on the
first six years indicates that with the present methods of se-
lection Florident yield is leveling off at a maximum slightly
above Whatley Prolific yield. During the same period yield rela-


tions between Whatley, Farmer Composite, and several standard
varieties have shown no significant variation. Prolificacy of
Florident expressed as percent of two-eared plants where What-
ley produced two ears for every plant began at 87 percent and
rose at a uniform rate to 96 percent in 1940. No records have
been kept of the relative size of first and second ears, but it has
been observed that size of second ears has shown marked im-
provement. Improvement of yield has been obtained for the
most part by increasing percentage of two-eared plants and size
of the second ear. The goal of two equal-sized ears on each plant
has been nearly reached and, as the yield curve shows, no further
rapid improvement of yield may be expected with present meth-
ods. Further improvement of yield will depend upon parallel
increase of the weights of both ears together for the most part.
Yield does not seem to be easily improved by selection after the
goal of two ears of equal size on each plant has been reached.
Percent weevily ears in the original Florident stock was
mid-way between Whatley and the Farmer Composite. It has
shown no significant change during six years of selecting husk
protection. This failure may be partly due to a counter effect
from selection for longer ears. Ears of Florident are longer than
the ears of Whatley Prolific, as may be seen by comparing Fig-
ures 1 and 2 with Figure 5. Flintiness of kernels has shown
marked increase in the six years of selection on Florident.
More rapid improvement of Florident corn might possibly
be obtained by introducing small proportions of other strains or
varieties that are particularly strong where Florident is weak.
Other breeding plans might be tried concurrently with mass
selection. The writers believe, however, that any extra effort
beyond straight mass selection will be more profitably expended
in the development of better hybrid corn. The next logical step
in the improvement of Florident is very probably the develop-
ment of a double cross hybrid of inbred lines derived from
Florident. That work has been in progress since 1938.
It is intended that mass field selection of both Florident
Yellow and Florident White, as outlined above, shall be continued
indefinitely on the farm of the North Florida Experiment Sta-
tion. Growers of Florident corn who do not practice field selection
of seed will do well to obtain a fresh stock every few years to
maintain prolificacy and yield.
Where native varieties and farmers' strains which produce
many one-eared plants are continued, it will almost certainly be
profitable to select seed from two-eared plants in the field. Both
ears are equally valuable for seed and both should be taken to

increase selection intensity. Maximum selection intensity de-
pends upon the average number of seeds from each plant which
grow into mature plants in the next generation. Under some
conditions each selected plant may produce 1,000 daughter plants.
Under other conditions the number of daughter plants may be
decreased to 500. Progress under the first conditions may be
twice as rapid as in the second case. In either case selection is
enforced only on the female side, since the pollen is a random
mixture from every plant in the field. Selection intensity with
mass selection of corn can never be very strong. All reasonable
care should be taken to keep it as high as possible by saving
seed from the smallest fraction of the best plants. The number
of selected plants should not be less than 10 if the weakening
effect of inbreeding is to be avoided. Any effort to select on the
male side by detasseling poor plants or otherwise is not recom-

Origin and General View of Hybrid Corn
Development of hybrid corn began about 1900 when several
men started making controlled hand pollinations. In 1908 Dr.
G. H. Shull of the Carnegie Institution reported that he had
produced inbred lines of corn by applying pollen to silks of the
same plant and excluding other pollen. The seeds thus produced
on one plant were sown in a separate row and self-pollination
was repeated. By breeding from only one parent plant each
generation, a highly inbred line was produced. All inbred lines
so far developed have been much weaker than the parent stock,
but very uniform in contrast with open-pollinated corn. As Dr.
Shull reported, the first generation cross of inbred lines is also
very uniform and much more vigorous than the inbred lines.
Some hybrids are markedly superior to the parent, open-pollinated
stock. When a good hybrid is discovered, its seed may be pro-
duced in commercial quantities year after year by recrossing the
parent inbred lines. Inbred lines after four to six successive self-
pollinations remain constant or breed true generation after gen-
eration because their heriditary makeup is fixed by the inbreed-
ing process. For the same reason, the result of crossing two
inbred lines is always the same.
The "hybrid method" with corn accomplishes virtually the
same result as vegetative propagation-mass production of su-
perior individuals which are identical in their heredity. Hybrid
corn bears much the same relation to open-pollinated corn that
budded progeny of a superior fruit tree bear to seedling pro-
geny from the same tree. Carrying that comparison further, it

is generally recognized that seedlings from a superior budded
fruit tree are usually inferior to the parent. By the same token,
seed from a superior hybrid corn produces inferior progeny.
Hybrid corn is reproduced anew each year by recrossing the
inbred parents lines. Farmer's crop hybrid corn should never be
planted as seed.
Definition of Hybrid Corn
The term "hybrid corn" by common consent, and by legis-
lation in some states, has been restricted in recent years to mean
the first generation, only, of a cross involving at least one inbred
line. Common hybrids are:
1. Topcross or in-bred-variety cross: the cross of an inbred
line with an ordinary variety
2. Single cross: the cross of two inbred lines
3. Three-way cross: the cross of an inbred line with an un-
related single cross, thus involving three inbred lines
4. Double cross: the cross of two unrelated single crosses,
thus involving four different inbred lines.
There are, of course, other possible hybrid combinations, but
the four listed here are the only ones used commercially to any
extent. The single cross is widely used with sweet corn. The
double cross is the most feasible one and the one most used with
field corn. Ears of the four inbred lines, two single crosses, and
the double cross hybrid, Fla. W-l, are placed in Figure 17, to
show how the double cross is made.
Development of Hybrid Corn in Florida
A complete program with hybrid corn involves first the de-
velopment of superior hybrids that are adapted to the climate and
soil of the region where they are to be grown. When a good hy-
brid has been developed, commercial production and planting
of hybrid seed corn may begin.
The preliminary process of developing good hybrids requires
several years. Steps in the process are: (1) Collection of founda-
tion stocks; (2) inbreeding, usually self-pollination by hand,
which must be done separately every year with each line as
long as it is kept in existence; and (3) test crossing of the best
appearing lines which may begin after one to three years of in-
breeding, and must be continued at least three years before any
hybrid can be safely considered acceptable for commercial use.
Development of hybrid corn by the Florida Experiment Sta-
tion began in 1927 when some 500 self-pollinations were made
on border rows of plots in the regular variety tests. Other new
self-pollinations were then made in the four following years until


Fig. 17.-Illustrating how double cross hybrid seed corn is produced
by crossing four inbred lines; first by pairs to produce two single crosses
and second by crossing the two single crosses. The pedigrees are of the
Florida Agricultural Experiment Station hybrid Fla. W-1.

10,000 inbred lines had been started. Most of these came from
a few varieties which had made the best records in earlier tests.
Some were derived from a single variety and others from crosses
of prolific varieties with native, one-eared, weevil-resistant va-
rieties. Here again, as with the foundation stock of the Florident
White and Florident Yellow varieties, the purpose was to com-
bine prolificacy and high yield with weevil resistance.
Many inbred lines with obvious defects were discarded im-
mediately (Figure 18.) Other lines did not produce enough seed
wo plant again and were lost. Each year some of the poorer ap-



Fig. 18.-Two inbred lines of corn (in foreground), one badly lodged,
the other fully erect.

pearing lines were discarded until only 500 were left of the
original 10,000. These lines were stable and uniform but of many
different types. Each line seemed vigorous enough for use in the
commercial production of hybrid seed.
The next step was to test the behavior of inbred lines in
crosses to determine which ones might make the best hybrids. It
may be noted now that 124,750 different single crosses and a
much larger number of double crosses may be made from 500
inbred lines. It was clearly impracticable to test that many hy-

brids. The inbred lines were first crossed with the variety What-
ley Prolific for a preliminary test. Those making the best records
were later combined into single and double crosses for further
testing.1 Many of the test crosses were grown on the Experiment
Station farms at Quincy and Gainesville. Records were kept in
each test on yield, weevily ears, ear rot, and lodging of the plants.
It was found that appearance of inbred lines is not a reliable in-
dication of yields produced by their hybrids. Lines which made
good yields in crosses with Whatley usually made good yields
when crossed with each other. However, a few lines were discov-
ered which produced two-eared hybrids and good yields in
crosses with Whatley but mostly one-eared hybrids and relatively
low yields when crossed with each other. Most of the hybrids
made relatively lower yields in comparison with Whatley Pro-
lific and other check varieties at Quincy than at Gainesville.
That result was not unexpected, since the inbred lines were de-
veloped at Gainesville and only those passing preliminary tests
at Gainesville were included in tests at Quincy. Development of
strong stalks, strong root systems, good husk protection, flinti-
ness, and freedom from diseases in hybrids is apparently de-
pendent upon a high average development of those characters
in the component inbred lines.
With the first cycle of breeding work completed, 50 inbred
lines have been retained from 10,000 original self-pollinations
made in open-pollinated varieties and crosses of such varieties.
Every one of the 50 lines has one or more serious faults. A second
cycle of breeding now in progress has so far produced 5,000
new lines derived from various combinations of the better lines
in the older group. Many of these new lines have been discarded,
but a goodly number of them appear definitely superior to any
of the older group. Testing of their hybrids is in the early stages,
but it seems likely that some of them may soon replace certain
lines that are now recommended in the double cross hybrid,
Fla. W-1. It also seems likely that a satisfactory yellow hybrid
combination may be found among the new yellow lines.

1. The making of test crosses did not impair purity of the lines, for each inbred line
was continued every year by self-pollination as a separate process.


Description of Inbred Lines and Single Crosses in the
Double Cross Hybrid Fla. W-1
Fla. W-1 is the only hybrid corn that has been released by
the Florida Agricultural Experiment Station. It is the double
cross of four inbred lines developed by breeding work discussed
in the preceding section. The
four inbred lines and the two
single crosses which combine to
make Fla. W-1 are described
here before presenting a pro-
posed plan for commercial pro-
duction of the hybrid seed.
These descriptions must not
be considered exact, since many 6
characters of the corn plant
vary a great deal with changes
of climate and soil. Pictures of
one plant and two ears of each
line and single cross are shown
in Figures 19 to 24. A descrip- .
tion of Fla. W-1 is given with
other commercial hybrids and
varieties of corn in a previous
section of this bulletin. The ped- B
igree of Fla. W-1 is (11 129 x
4 32) x (B5-11xB1-18).

Inbred Line 11-129
Origin-Whatley Prolific, first
self-pollination made in 1931.
Characteristics Very pro-
lific, most productive of the four
lines, long tight husks, smooth
dent kernel type, weak root
system allows many growing Fig. 19. Inbred line 11-129.
plants to lodge in wet weather, Typical ears and plant.
white seed, deep red cob. This line sheds pollen freely and pro-
duces many suckers. Nevertheless, it is best used as the seed
parent of the single cross 11-129x4-32 because of its higher yield
of seed.

Inbred Line 4-32
Origin Smith, first self-
pollination made in 1928. Smith
is a white single-eared weevil-
resistant variety from N. M.
Smith, River Junction, Florida.
It was included in early varie-
ty tests at Gainesville.

Characteristics Two-eared
with second ear smaller than
the first, long tight husk, dent
kernel type, medium strong root
/ system, slender stalk, slightly
S Crooked neck causes tassel
i branches to lean mostly on one
side, white seed, white cob. This
line does not shed pollen as
freely as 11-129 but its seed
production is so much poorer
that it is best used as the pollen
parent for the single cross 11-

Single Cross, 11-129x4-32

Origin-Seed made up anew
i each year by using pollen from
-' 4-32 on silks of 11-129.
S' Characteristics-Prolific with
three ears on many plants. Pro-
duction 15 percent lower than
Fig. 20.-Inbred line 4-32. Typi- tight husks
cal ears and plant. Fla. -, l tight husks,
smooth dent kernels, resistant to
weevils, medium strong root system, may lodge under some con-
ditions, white seed, red cob. This single cross is recommended for
the seed parent in making the double cross because of higher
production of inbred line 11-129. Inbred seed to plant two-thirds
of the larger single crossing plot and single cross seed to plant


three fourths of the double
crossing field are both borne on
plants of one of the four in-
bred line;. The most produc-
tive line, 11-129 is recommend-
ed for that purpose.

Inbred Line B5-11
Origin-Florida Flint crossed -
with Cuban Flint in 1926, self-
pollinated 1927, outcrossed 1928,
first seed-pollination to start p
B5-11 made in 1929.

Characteristics Two-eared,
second best producer of the four 7
lines in Fla. W-l, first ear often / 1 i
fails, long tight husks, flint type
kernels, medium strong root 6
system, white seed, white cob.
This line is used as the seed
parent in the single cross B5-
llxBl-18 because it is more
productive than B1-18.

Inbred Line B1-18
Origin-Cuban Yellow Flint I
self-pollinated 1927, outerossed
1928, first self pollination to
start B1-18 made in 1929.
Characteristics Two-eared
with second ear smaller than
first, least productive of the N
four lines in Fla. W-1, long
tight husks, semi-flint type ker-
nels, very strong root system,
seed ordinarily pass as white but
do have faint yellow tinge, white
cob, ear presses tightly against
stalk frequently causing crook Fig. 21.-Single cross 11-129 x
of the stalk as shown in Fig. 23. 4-32. Typical ears and plant.

(That peculiar character often appears also in Cuban Yellow
Flint corn.) This inbred line is used as pollen parent in the
single cross B5-llxBl-18 because of its poor seed production. It
does not shed pollen freely but pollinates B5-11 satisfactorily.

Single Cross, B5-llxBl-18
Origin-Seed made up anew
Ak each year by using pollen from
M B1-18 on silks of B5-11.



Fig. 22. Inbred line B5-11.
Typical ears and plant.

Characteristics Two-eared,
production 12 percent below
Fla. W-l, long tight husks,
smooth dent kernels, resistant
to weevils, strong root system,
tall slender stalk, seed ordinari-
ly pass as white but do have a
, ery faint yellow tinge, white
cob. This single cross is used
as the pollen parent of Fla.
W-1 because production of sin-
S gle cross seed on B5-11 with
B1-18 pollen is much lower than
production of single cross seed
on 11-129 with 4-32 pollen. This
single cross is planted in one
S pollen row to every three seed
rows of the other single cross
in the double crossing field.

The other four possible single
crosses which may be made from
the four inbred lines, viz. 11-
129 x B5-11, 11-129 x B1-18.
4-32 x B5-11, and 4-32 x B1-18,
are not described here. They
are not used in making double
cross seed because of the three
possible double crosses, siz. (11-
129 x 4-32) x (B5-11 x B1-18),
(11-129 x B5-11) x (4-32 x Bl-
18), and (11-129 x B1-18 x
(4-32 x B5-11), the first pro-
duces the best yield. It is also


more practicable to make that
combination because of differ-
ences in seed production of the
four inbred lines.



Fig. 23. Inbred line B1-18. Fig. 24-Single cross B5-11 x
Typical ears and plant. B1-18. Typical ears and plant.

Fig. 25.-General plan for production of double cross hybrid seed corn.

Inbred Line,
11-129; 1/6 acre

a a a a a a a a a a a a
a a a a a a a a a a a a
a a a a a a a a a a a a
a a a a a a a a a a a a

Inbred Line,
4-32; 1/12 acre

b b b b b b
b b b b b b
b b b b b b
b b b b b b


25 acres, (a) seed rows
12.5 acres, (b) pollen rows

37.5 acres to make (ab)
single cross seed

One pollen row b b b b
Two seed rows, a a a a
detasseled a a a a
One pollen row b b b b
Two seed rows, a a a a
detasseled a a a a
One pollen row b b b b
a a a a
aa a a
b b b b

8.35 acres, (c) seed rows
4.15 acres, (d) pollen rows

12.5 acres, to make (cd)
single cross seed

One pollen row d d d d d
Two seed rows, c c c c c
detasseled c c c c c
One pollen row d d d d d
Two seed rows, c c c c c
detasseled c c c c c
d d d d d
C c C c C
d d d d d

Inbred Line,
B5-11; 1/18 acre

ccc c
cc c
c c c c

Inbred Line,
Bl-18; 1/36 acre



Grading Seed Corn
It is good practice to run any lot of seed corn through a
grading machine to remove large round kernels and small kernels
which are usually discarded. Hybrid seed corn is likely to have
a higher proportion of large round kernels than ordinary seed
because pollination may not be so completely done. Three-fourths
of the tassels are pulled in a double crossing field. Large kernels,
and medium size kernels of irregular shape are good seed except
that they may interfere with regularity of drop in machine plant-
ing. With the higher price of hybrid seed, such kernels are
worth saving for planting separately.
In some sections where hybrid corn is being grown exten-
sively, the see:l is separated by shape and size into 15 or more
different grades. A suggested grading plan for hybrid seed in
Florida is:
Grade Screen Dimensions
Round hole Slotted
Large flat Over 21/64 inch through 13/64 over 9/64
Medium flat 19/64 to 21/64 through 13/64 over 9/64
Small flat 17/64 to 19/64 through 13/64 over 9/64
Large round Over 20/64 through 16/64 over 13/64
Medium round 17/64 to 20/64 through 16/64 over 13/64
These five grades may be reduced to three by combining
medium and small flats, and large and medium rounds.


F44 x F6 GT112 x L578

F44 F6 GT112 L578

Characteristics of Dixie 18
Yellow hybrid-adapted to Coastal Plain-highest yielding corn
for this region-excellent root strength to resist drought and
lodging-superior standing ability-good weevil resistance-two
eared-good size-tight shuck for insect protection-medium hard


F1x F2 F3x F4

F1 F2 F3 F4

Characteristics of Fla. W-1
White hybrid-adapted to north Florida, Southern Georgia, and
extreme southern Alabama and Mississippi-highest yielding white
hybrid-most weevil resistant hybrid-good stalk and standing
ability-good drought resistance-prolific eared corn-heavy and
tight shuck for insect protection-hard kernel-very good crib

Dr. Wayne Henry Freeman, Dr. Fred Hull, Head Agronomy
Agronomist, U. S. Department of Department, Florida Experiment
Agriculture, stationed at Georgia station. Bred Florida W-1 in 1938.
Coastal Plain Experiment Station, Also developed two of the inbred
Tifton, Georgia, in charge of corn lines in Dixie 18. Agronomist and
breeding. Bred Dixie 18 in 1946 active leader of corn breeding
from Georgia, Florida, Louisiana from 1927 to date at Gainesville,
inbred lines. Florida.

DIXIE 18 HYBRID CORN (Formerly GCP 6001)
Pedigree (F44xF6) x (GT112xL578)
Dixie 18 is a yellow-grained corn hybrid adapted to the Coastal
Plain. It was developed by the Georgia Coastal Plain Experi-
ment Station and the United States Department of Agriculture
as a part of the cooperative corn improvement program of the
Southern Corn Improvement Conference.
Two of the parental inbred lines of Dixie 18 were developed
at the Florida Agricultural Experiment Station, one at the
Louisiana Agricultural Experiment Station and one at the
Georgia Coastal Plain Experiment Station. The line from Louisi-
ana is the only one isolated from an open-pollinated variety. The
other three lines are the result of inbreeding, crossing, and again
inbreeding to obtain the characters being sought.
Dixie 18 was first tested in 1946. Crosses among the parental



Florida Experiment Station, New-
ell Hall, birthplace of Florida W-1
and two parents of Dixie 18.

)urtesy Greenwood Farms.



urtesy Greenwood Farms.

Georgia Coastal Plain Experiment
Station, birthplace of Dixie 18.

'.;. .... : .. *. ;:.

.. .' ..I .!
XN-11 ''


inbred lines tested in 1945 indicated that the Dixie 18 combina-
tion would be productive. Sufficient seed (20 bushels) was pro-
duced in 1946 for trial plantings by county agents and farmers
and for more extensive experimental testing in 1947. Reports
were obtained in 1947 from 21 experimental trials and 21 strip
plantings made by county agents. The results of all tests over a
wide range of conditions indicated a superior yield and standing
ability and equal performance in weevil resistance for Dixie 18
as compared with Whatley. Results of these tests are presented
in Tables 1 and 2.

Table 1.-Performance of Dixie 18, Florida W-l, and Whatley,
1945 and 1946

Variety or Hybrid Acre Yield Ears
Percent Erect Per Weevily
1 2 of Plants 100 Ears
1945 1946 Average Whatley Plants
bu. bu. bu. % % no. %
Dixie 18 ........ 52.9 63.1 58.0 121 85.8 148 13.6
Florida W-l .... 44.2 55.2 49.7 104 69.3 157 6.1
Whatley ........ 44.2 51.8 48.0 100 51.9 154 5.5
1. Two locations. Yield for Dixie 18 was predicted from the four non-parental single
2. Average of eight tests at four locations.

Table 2.-Summary of the Performance of Dixie 18 in 1947

Acre Yield Erect Plants Ears Per Weevily
Percent 100 Plants Ears
Dixie Check of Dixie Check Dixie Dixie
18 Check 18 18 Check 18 Check
bu. bu. % % % No. No. % %
Ave. of 21 expts.1.. 43.7 33.6 130 86 72 114 113 16.4 18.8
Av. of 21 farmer
strip tests2 ...... 52.7 46.5 113 .. .. 158 159 14.1 14.9
Av. of all plantings. 48.2 40.0 120 86 72 140 140 15.2 16.7
1. Check was: Whatley in 19, Florida W-1 in two.
2. Check was: Whatley in 13, Florida W-1 in 6, Local in two.

Dixie 18 is a full season hybrid with the same maturity of
Whatley Prolific but slightly earlier than Florida W-1. Under
good growing conditions it is tall but has excellent stalk and root
strength to resist lodging. It has a larger ear than either Florida
W-1 or Whatley and is of about the same degree of prolificacy as
Whatley at ordinary fertility levels. At low. yield levels it has
more ears per plant than Whatley. The grain is yellow and of a
medium texture, being harder than Whatley but not so hard as
Florida W-1.



Hybrid corn that is purchased by the farmer is known as first
generation seed. Experiments have indicated that second genera-
tion seed will yield 15 to 35 percent less than first generation
seed. For this reason, farmerss should not attempt to save seed
from their hybrid corn planting-s. As the seed cost for corn is
less than for almost any other crop, it is very uneconomical to
save seeJ costs by planting second generation seed from their
own crop.
The cooperation of Exper'ment Station workers, county agents,
and farmers in growing and obtaining data on many of these
trial plantings is greatly appreciated. Without this cooperation
the evaluation of Dixie 18 in such a short time would have been
delayed several -ears.

Thick, well-fertilized stands of corn hold weed and grass growth In
check. Weed and grass growth is heavy in thin stands of corn.

Control weeds and grass by early, shallow cultivation. Avoid deep
cultivation which prunes the feeder roots.
(Courtesy South Carolina Experiment Station)


THE FERTILIZER requirements of corn vary from soil to soil, and
the farmer should contact his county agent for the latest infor-
mation. However, in general 400 to 600 pounds of a 4-8-8 ferti-
lizer should be used in the drill at planting time. If the soil on
which corn is to be grown has been worked intensively for years,

Correctly fertilized and cultivated corn will stand out to the row
against neglected corn. (Photo by courtesy of U. S. D. A.)

10 to 20 pounds of zinc sulphate should be used to the acre mixe 1
in the complete fertilizer. Either at the first or second cultiva-
tion at least 60 to 80 units of nitrogen should be applied as a side
dressing. If nitrate of soda is used, it should be placed at the
second or last cultivation and at the rate of at least 300 to 400
pounds to the acre. Some of the slower acting nitrogens, which
in many respects are preferred for corn, such as cyanimide, ura-
mon, ammonium nitrate, should be used at the first cultivation.
The amount of these should be based upon their nitrogen con-
tent; thus 100 pounds of ammonium nitrate contains 32 units of
nitrogen, 100 pounds of cyanimide, 20 units of nitrogen, uramon
42 units, whereas nitrate of soda has only 16. Nitrogen ferti-
lizers such as uramon or cyanimide can be applied broadcast
before planting time if desired.


In this article it is our aim to give you an understanding of
some of the facts or principles that play a part in supplying your
corn with all the plant food nutrients needed to make big crops.
When you have these facts you have the tools needed to figure
out for yourself the best procedure to follow for any particular
field or soil. Since you are more familiar with the past history
and present performance of your particular field than anyone
else, you are in a position to be your own doctor in handling

Showing the effect of certain fertilizers on muck soils. Left plot
received potash and copper sulphate the previous year. Right plot
received no treatment. Potash is usually the deficient fertilizer nutrient
on muck and peat soils. Many of the peat and muck soils also respond
to copper treatments.

your soil by coupling your own information with the facts we
present here. You can diagnose your particular case and prescribe
a more accurate prescription (specific fertilizer recommendation
for your field) if you know a lot about the patient (the corn),
about the home (the soil), about the medicine (the fertilizers),
and about the living conditions (the rainfall, depth of plowing,
stands, weeds, etc.) If all these are considered, it will not be
necessary for you to follow the old almanac procedure and stay
with blanket or general fertilizer recommendations that are inade-
quate because they must fit into the mid-zone of all the produc-
tion problems. General recommendations are somewhat like the
same pills for all ills.







-Courtesy Greenwood Fa

91 A 7


A. Corn Production is a Manufacturing Process
1. One important aspect of farming is to convert the raw ma-
terials of the soil, chiefly nitrogen, phosphorus, potassium,
calcium, magnesium, sulphur, and boron, into feeds, foods,
fibers, and oils. This is a manufacturing process. If the raw
materials are available to the plant factory in adequate
amounts, the growing processes, or the manufacturing, can
proceed as fast as the genetic capability of the crop will
permit. Of course it is important that the growth is not
limited by too little or too much moisture, or by unfavorable
temperatures or light conditions, and cultural care must be
considered, such as protection from weeds, good stands, sea-
sonable planting, freedom from diseases and insects, and
storm damage.
2. If any one or more nutrient raw materials are present in
scanty amounts the crop yield must be correspondingly de-
creased. Thus, if you want to make big crops on poor or
exhausted soils, it is necessary to supply or replenish the
soil with these raw materials in the form of fertilizers. In
order to be efficient in fertilizer practices it is necessary to
understand what it takes to make a big crop, how plants
feed, how fertilizers act in the soil, and something about soil
moisture. If all plant requirements are met in the most effec-
tual manner, big crops can be produced. If not, this farm
manufacturing process of growing big crops cannot continue
to its fullest capacity.
3. The greatest problems in maintaining the supplies of raw
materials for crops are with nitrogen, phosphate, and potash.
a. The other necessary raw materials are sometimes limiting
but in general:
1. Calcium and magnesium are most economically replen-
ished to the soil through liming with dolomitic limestones;
2. Sulphur is usually abundant in superphosphate made
with sulphuric acid, also in ammonium sulphate, and in
rain water, for about 10 pounds are added per acre an-
nually in the sulphur washed out of the smoke of the air.
3. Boron is needed only in trace amounts and most acid
soils still contain such quantities. The need for boron is
associated chiefly with heavily limed or alkaline soils.
b. This article will deal only with the nitrogen, phosphate and
potash factors.


B. The Requirements of Corn for Nitrogen, Phosphate, and
1. Any one of the above factors can become a bottleneck in the
production of the corn if available in quantities less than
those shown in Figure 1.
2. If all the nitrogen, phosphate, and potash needed to make a
100-bushel crop were to be supplied in one dose to the soil,
it would require the equivalent of about 1,300 pounds per
acre of a 10-10-10 fertilizer. (Here allowance has been made
for fixation into unavailable forms of about two-thirds of the
phosphate added.)
3. When 100 pounds of a mixed fertilizer as 3-12-12 is used per
acre, the soil must supply about
98% of the nitrogen,
91% of the phosphate, and
91% of the potash
if a 100-bushel corn crop is to be made. Thus, fertilizer ap-
plied at the 100-pound rate is largely a starter fertilizer. If
the soil contains only enough nutrients to make a 40-bushel
crop, the 100 pounds of starter fertilizer will not be enough


lNM 0W

I S ,

to, T

Figure 1.-The quantities of raw materials needed to make the ears
and stover for a crop of 100 bushels of corn per acre. If any of these
materials are available in smaller amounts than shown the yield must
be reduced proportionately. Most of the fertilizer problems are con-
cerned with the supplies of nitrogen, phosphate, and potash; although
the moisture supply is frequently the first limiting factor on sandy
soils and where the soils are low in organic matter.


to produce 100 bushels of corn and more fertilizer must
be used.
4. If a big crop is wanted from a poor soil it is necessary to
supply the raw materials as fertilizers to the soils. When
these are used in the most effectual manner, the big crops
can be produced. If the raw materials are not provided, the
farm manufacturing process must be slow and inefficient or
must finally stop.
This article reports on experiments dealing with factors that
affect the use of fertilizers, particularly carriers of nitrogen,
phosphorus, and potassium, in making them most effective in
feeding the corn plants to get acceptable yields on poor soils as
well as increasing yields on good soils. If greater corn yields can
be made economically while building the soil for other crops,
many new opportunities will be available to farmers on exhausted
soils. We have not fully realized that some farm practices which
looked good economically were good only in part and for a short
pull, because the practices may have been slowly but relentlessly
robbing the soil of some factor or factors that would bring on
new and costly deficiencies. We have sometimes called a practice
profitable when it was merely cashing in on the capital of soil
In venturing into this study we hoped to find a direct way to
fertilize crops on poor soils so as to get big crop yields quickly
without having to wait several years to build the fertility through
well established rotation practices. We hoped that by getting the
yields up to an acceptable level quickly, the farmer could then
switch into a good rotation and soil maintenance practice and be
in the farming business to stay.
We hope here to sort out some facts that will help to lay a
foundation for a more sound farming program on the basis of
a more fertile soil.
A. Decline in Soil Fertility Not a Simple Process
1. Many soils were highly fertile in the virgin state. Big crop
yields were possible without fertilizers. In general nitrogen
became the first limiting nutrient element, especially on the
light-colored, upland soils. For many years the soils were
sufficiently supplied with phosphorus and potassium to make
good clover crops merely by the addition of lime. When
legumes were grown on these soils the nitrogen content was
temporarily increased, the crop that followed the legumes

had the benefit of this added supply of nitrogen, and their
yields increased as a result. This often was mistaken as a
soil-building process. Eventually the supply of phosphorus
and potassium dwindled, and clover failures became more
2. The havoc of declining soil fertility has been cushioned for a
time by the plant breeders through the development of im-
proved varieties of hybrid corn. These varietal improvements
have helped, for they give the farmer more efficient machines
to use in his manufacturing process; however, we must recog-
nize that they make a greater demand on the soil for the
fertility elements.
3. Another great cause of the decline in soil fertility is erosion.

B. Some Views on the Use of Fertilizer for Corn at the
Beginning of This Study
1. It was an established fact that soil fertility could be main-
tained by the use of a rotation that included legumes cloverss),
where the bulk of sufficient mineral fertilizers as phophate
and potash were added to the small grains in the rotation,
in order to aid the legumes that would supply the nitrogen
for the corn, and where lime was used to correct soil acidity.
2. The need for nitrogen fertilization was recognized as early
as 1922 by Conner (2) who stated, "Except on those soils
which still have a large portion of unexhausted nitrogen left,
the nitrogen problem is the most important soil fertility
problem before the Corn Belt farmer and the time has ar-
rived when the lack of nitrogen is seriously reducing yields."
3. It has been found that about 100 to 200 pounds per acre of
a fertilizer as 0-14-7 or 0-12-12 was all that could be profit-
ably used in the row for corn. Other methods of application
had not been thoroughly studied.
4. It had been concluded that "where less than six pounds of
nitrogen per acre in a mixed fertilizer was used, that a
phosphate-potash fertilizer in the row was preferable to
fertilizers containing nitrogen in addition." (3) Apparently
the corn plants received some growth stimulation in the early
growing period from the nitrogen in the mixed fertilizers.
There was no explanation why this nitrogen failed to increase
the yields where nitrogen was undoubtedly needed, other
than that the amount of nitrogen used was too small to
produce much increase in yield.
5. In 1933, Wiancko, Walker, and Mulvey (5) stated, "The
effects of nitrogen applied to corn, either at planting time or


as side-dressings later, were quite variable. The results indi-
cate that neither practice is practical for increasing corn
yields." In some instances good responses were obtained from
the side-dressing treatment; it appears that this occurred in
the seasons when the mid-summer rains were ample. In 1934
Miles (3) concluded that, "Further research is needed to
determine whether any rate, method, or time of applying
nitrogen for the corn crop will be profitable." At the time
of starting this work Walker and Wiancko (6) had plowed
under cyanamid for corn. There were indications that this
method had certain advantages.

C. Some Considerations That Influenced Us to Make This Study
1. Nitrogen starvation symptoms of the corn in many of the fields
of Indiana and particularly in the southern half of the state
emphasized that there was a real deficiency of this nutrient.
There were many fields, particularly on the black colored
soils, that showed marked potash starvation symptoms. It
was generally recognized that more available phosphate was
needed everywhere. These facts indicated that one could not
go far with any direct fertilization of corn with phosphate
and potash without adequately and effectively supplying the
nitrogen. Also, it was equally true that if one were to expect
any benefits from applications of nitrogen, the nutrient bal-
ance with respect to phosphate and potash must be maintained.
We recognize that on some very poor soils the corn showed no
starvation symptoms excepting poor growth and poor yields,
and that in such instances a complete fertilization in ade-
quate amounts would be necessary for big crops.
2. We puzzled over the fact that experiments with side-dressing
corn with nitrogen (5) made good increases in yields in some
years and none in others. We recognized that the character-
istic midsummer season had dry periods of from two to eight
weeks. We noted that these droughts frequently come at
critical periods in the growth of the corn when the greatest
demands for nutrients are being made by the plants. Were
the years of good response associated with rainfall that moved
the nitrates into the soil where they were accessible to the
roots? On the other hand, did the nitrates remain on top out
of reach of the roots in dry seasons? Perhaps the droughts
were not so damaging on the best soils when they contained
more of the native organic matter for holding water and for
giving up gradually the supplies of native fertility elements.
With the decline in the organic matter and nutrient content

of the soil by crop removal, cultivation, and erosion, the pres-
ent poorer soils have become nutrient-deficient mineral car-
casses. Restoration practices would have to take into account
the characteristics of the soils as to their chemistry, biology,
and physics, as well as those of the plant, the fertilizers, and
the rainfall in order to be most effective. The complex nature
of this problem made our research approach take on a step-
at-a-time characteristic to find, if possible, the reasons for
the different performances.
3. We thought about the behavior of nitrate nitrogen in soils in
contrast to that of ammonium nitrogen, and visualized a re-
lationship somewhat as set forth in Figure 2. From this con-
sideration we saw a possible advantage in plowing under the
nitrogen in an ammonium or ammonium-forming form as am-
monium sulphate, cyanamid, or urea, so as to keep it in an
immobile condition. This, we thought, would cause it to remain
in the deeper, moist soil where it would be accessible for the
roots in dry periods.

The results obtained from different fields and seasons have not
been averaged, because averages destroy the significance of indi-
vidual cases. In a fertilization study of this kind, involving many
significant variables such as weather, average figures tend to cover
many important facts. It was not the average of the first ten at-
tempts to fly aeroplanes that determined whether planes could
fly. It was the first successful attempt that proved the principle
that they could fly, and it was not necessary to fly 10 or 100 more
planes to establish the fact.
No attempt at comparisons between cyanamid or ammonium
sulphate as carriers of nitrogen is made in these investigations;
in fact, direct comparisons are impossible for the two materials
were not used in the same field. Both carriers have been used inter-
changeably and both have performed satisfactorily as carriers of
an ammonium source of nitrogen. The rate figures for nitrogen
are expressed on the basis of the elemental nitrogen in pounds
per acre. Thus, 20 pounds of nitrogen (N) per acre is about
equivalent to 100 pounds of cyanamid or ammonium sulphate.

A. 1939 Results
1. This season was characterized by adequate and well-distributed
rainfall until about August 10. The late growing period was
very drought.
2. The yield data are shown in Tables 1 and 2.


3. What was learned in 1939.
a. Where nitrogen is needed for corn it can be used directly
by plowing it under in adequate amounts (80 pounds of
nitrogen per acre), but it must be balanced with adequate
amounts of phosphate and potash.

FhnnMoniu Sulfate sodium Nitrate
(N th catm) (N .u cn *fn)

RriouN AnTI Bfteria pw. eneQgrS O ano w n / >T"
T. -(o)i{ ( Waer) Lu i }lOdure \
\(Uh imdete S) t pu warm tm rilure j (L h 0ePiy air)

Ammonia is held the t aI part- Sodium is held bij the (la parlile
i and is not monvablr and the nitrate is fre to move

Q0S7 GS- (X-Pa-ine 08--- G

SulfuricAld aldum Sulfate Nitric Arid Cakium Nitrate
Figure 2 --When the nitrogen is in an ammonium-form as in am-
monium sulfate it is in the part of the molecule that carries a positive
electrical charge. Cyanamid and other ammonium-type nitrogen
carriers decompose to form the ammonium ion which behaves as shown.
In this form nitrogen is absorbed or embraced by the soil particles in
such a way that it cannot move in the soil solution. As long as the
nitrogen is in the ammonium ion, it cannot leach out of the soil in
periods of excessive rainfall or move to the surface of the soil out of
reach of the roots in dry periods. Organic matter helps keep the nit-
rogen in the ammonium form because it supplies energy for bacteria
that use up free oxygen in the soil, thus preventing ammonium-nitrogen
from oxidizing to nitrate-nitrogen. Under moist, warm conditions in
the presence of plenty of air, and with a shortage of organic matter
ammonium-nitrogen is converted to nitrate-nitrogen in a few hours.
In this form the nitrogen is in the part of the molecule that carries a
negative electrical charge. In this nitrate form it is not held by the soil
and is free to move with the soil moisture. It will not stay "put" in
this form. Both forms are available to plants. The nitrogen in am-
monium-forming nitrogen carriers is eventually converted to nitrate-
nitrogen in the soil. The advantage of placing this form of nitrogen
deep is that it is held longer in the root zone and is more accessible
to the roots in dry periods and when the plants need it in the largest
If nitrates were placed deep with organic matter, it is possible that
the nitrates might be converted to ammonium-nitrogen and thus be
made immobile. This, however, has not been investigated.


b. About two pounds of nitrogen are required to produce one
bushel of corn under conditions where nitrogen is the only
limiting factor. (Table 3.) However, in exceptional in-
stances where 20 pounds of nitrogen was side-dressed in
addition to nitrogen plowed under and used in the row (a
doubtful practice on account of dry weather), up to one
bushel of corn was produced per pound of nitrogen.
c. On land where nitrogen is a first limiting growth factor
and all other factors are adequate, an increase in corn
yield can be expected from side-dressing with nitrogen early
in July, provided there is adequate rainfall to move the
nitrogen into the soil after the application and to finish
the crop. Poor or no increases will be made if other factors
as dry weather, poor stands, weedy corn, or inadequate
phosphate and potash are limiting.
d. Firing of the lower corn leaves is caused by a lack of
nitrogen and also from a shortage of potash. (Nitrogen
starvation symptoms result in the leaves dying along the
midrib from the tip of the leaf. Starvation for potash shows
a marginal dying of the edge of the leaf. These symptoms
appear first on the lower or older leaves.) Nitrogen firing
has often been mistaken for a shortage of moisture. The
first symptom of moisture starvation is rolling of the leaves.
e. The supply of nitrogen had a direct effect on the protein
content of the grain. (See Tables 3 and 4.) No data were
obtained on the quality of protein in the corn; however, an
interesting comparison can be made. From Table 4 we see
that if Farmer Brown produces only 29 bushels of corn per
acre from unfertilized soil as in plot 1 he would need to
grow about four acres of corn to get the same amount of
protein as Farmer Jones got on the same soil from one acre
fertilized as in plot 12 and where the yield was 91 bushels
per acre. In other words, when the yield was increased three
times, the protein production was increased four times.
Farmer Brown would also have to feed 128 bushels for
every 100 bushels Farmer Jones fed to be supplying the
hogs with the same amount of protein. If both farmers fed
the same amount of corn, Farmer Brown would have to
feed in addition about 300 pounds of a protein supple-
ment, such as a 44 per cent protein soybean meal valued
at about $6.66, with each 100 bushels of corn to be on a
comparable basis' with Farmer Jones feeding corn grown on
soil well balanced in fertility and producing big yields.
f. When a phosphate-potash mixture as 0-12-12 or a 3-12-12

Table 1. Average corn yields obtained from quadruplicate plots in 1939 from applications of nitrogen and muri-
ate of potash broadcast on the ground and plowed under with the previous crop residue on six soils where 300
pounds per acre of 0-16-4 were added in the row at planting time. Rainfall was plentiful until about August 10;
the late growing season was drought.

Materials plowed under
pounds per acre

Nitrogen Potash
N K20

silt loam






silt loam






silt loam






silt loan






fine sandy loam







silt loam





Significant difference .......... 3.3 4.2 3.8 5.3

Yields are in bushels per acre of No 3 corn. All corn yields reported in this bulletin are corrected to 17.5 per cent moisture.

Table 2. Average corn yields' obtained from triplicate plots in 1939 from various mixtures of fertilizers applied in
the row with and without nitrogen broadcast and plowed under and with nitrogen side-dressed about the 10th
of July on four soils. The growing season was characterized by adequate and well-distributed rainfall until about
August 10th. The late season was very drought.

Plot under,
number pounds
per acre

1 None
2 None
3 None
4 None

5 41
6 41
7 41
8 41

9 82
10 82
11 82
12 82

Significant difference.. ...... ....... ....

silt loam

silt loam

loamy sand

in row2











45. i
























silt loam






Yields are in bushels per acre of No. 3 corn and field weights o' sto er at husking time.
2600 pounds per acre o'l ClerTont, Vigo, and Crosby, and 400 pounds per acre on Miami.
Wet weather delayed the cultivation until the field was extremely weedy and then the corn was cultivated only once. The stand was poor. :t was apparent from nlant tiasil
tests that the yield was limited by factors other than the supply of nitrogen, phosphorLt, and potassium.

Table 3. The relationship between nitrogen added to Clermont and Vigo silt loam soil in 1939 and the increases
in yields of ear corn the protein content of the grain and the recovery of the added nitrogen.

Clermont s

Bushels per acre and
Lbs. nutrients added increase from N. Ponds
Plot per acre (see Table 2) (Nitrogen) Nitrogen
No. to make
N P205 K20 one b:l.
Yield Increase Increase

1 0- 0 0 17.7 ....... .......
2 0-72-72 11.0 .............
3 18.0-72-72 18.6 7.6 2.4
4 38.5-72-72 38.3 27.3 1.4

5 41.0- 0- 0 23.3 12.3 3.3
6 41.0-72-72 32.3 21.3 1.9
7 59.0-72-72 24.3 23.3 2.5
8 79.5-72-72 53.8 42.8 1.9

9 82.0- 0- 0 36.8 25.8 3.1
10 82.0-72-72 42.5 31.5 2.6
11 100.0-72-72 45.1 34.1 2.8
12 120.5-72-72 70.9 59.9 2.0

Average pounds nitrogen to make 1
bushel increase (all nitrogen plots)... 2.39

Average pounds nitrogen to make 1
bushel increase (PW,-K2sO plots).... 2.16

ilt loam

Total lbs. Per cent
Nitrogen Nitrogen
in ears recovered
and byearsand
Stover Stover

9 .7 .......
14.8 18.3
26.9 40.1

15.1 8.8
21.6 24.6
23.4 20.2
41.3 37.5

27.7 19.7
27.3 19.3
29.5 18.0
56.3 37.0

Average )ounds nitrogen to irae 1 b ishel of cmrn increase for both soils where phosphate and pctash were used = 1.90.

Vigo silt loam

Bushels per acre

per b:l.












per bu.



N. in
ears and




Per cent
N. re-
by ears




to make
one bu.






Table 4. A comparison of the yields and protein content of corn grown with no fertilizer, an unbalanced fertilizer,
and a balanced fertilizer on the cost per pound of protein in the corn grain, on a Vigo silt loam.

Yield % Equivalent for equal Cost of Equivalent costs Cost to
Plot Fertilizer bus. protein protein fertilizer make
No. treair.ent per acre in grain per acre Total 1 lb. protein
Bushels Acres Fertilizer Overhead

1 None............. 29 6.31 128 3.9 $ 0.00 $ 0.00 $ 66.30 $ 0.179

3 600 lbs. 3-12-12... 31 5.19 154 4.5 10.00 45.00 121.50 0.328

12 600 lbs. 3-12-12
100 lbs. nitrogen' 91 8.003 100 1.0 21.00 21.00 38.00 0.103

1 600 pounds per acre of 3-12-12 in the row and 80 pounds of nitrogen per acre broadcast and plowed under and 20 pounds of nitrogen side-dressed early in July.
2 Based on farm management figures of about $17.00 per acre for overhead charges of making one acre of corn (1). The $17.00 is multiplied by the number of acres needed tn be
equivalent to one acre as in plot 12, $17.00 X 3.9 = $66.30 for plot 1, and ($17.00 X 4.5) + ($10.00 X 4.5) = $121 50 for plot 3.
3 We have reason to believe this corn ran short of nitrogen before the end of the season as indicated by tissue tests and plotted data of increases in yields from nitrogen added.
On other tests in following years where the nitrogen supply was adequate up to the time of maturity the protein content was as high as 12.5 per cent.

Table 5. Average corn yields1 from quadruplicate plots in 1940 from appli-
cations of nitrogen and muriate of potash broadcast on the ground and
plowed under with the previous crop residue on four soils where 300
pounds of 0-16-4 were added in the row at planting time. From the middle
of June to August 12 the moisture supply was critically short.

Materials plowed
under, lbs. per acre
Bedford Crosby Miami Clermont
silt loam2 silt loam silt loam2 sill loam
Nitrogen Potash
(N) K(O

0 0 12.9 29.5 25.2 16.6
21 0 34.2 36.3 15.5 39.5
42 0 27.7 49.4 29.2 51.7
84 0 26.7 52.8 34.0 51.4

21 50 31.6 49.4 17.5 42.1
21 100 33.6 50.1 17.6 43.1

42 50 17.7 56.2 24.5 59.4
42 100 19.6 59.3 23.7 57.2

84 50 23.2 68.1 33.9 73.5
84 100 24.0 71.8 36.7 74.4

0 50 12.7 30.8 25.2 16.5
0 100 9.9 33.8 24.5 16.7

Significant difference.. 6.3 3.2 3.2 5.0

1 Yields are in bushels per acre of No. 3 corn.
2 The injury from drought was particularly severe on these soils.

fertilizer low in nitrogen is used for corn on land that is
very deficient in nitrogen, the corn will start off well and
will make an increased yield of fodder, but the ears will
be formed when the plant is very short of nitrogen and
the yield may be cut below that where no fertilizer is used.
Increases in corn yields will not be obtained from phosphate-
potash mixtures or from mixed fertilizers carrying only
two or three per cent nitrogen if the corn begins to show
nitrogen starvation symptoms before time of tasseling.

B. 1940 Results
1. The 1940 growing season followed a dry fall in 1939 and a dry
early spring in 1940. The planting season was moist, but from
the middle of June until the middle of August the moisture
supply was critical. The hot weather at pollen-falling time


caused much damage to the pollination of the ears. The mois-
ture factor was greater than that of nutrition throughout
most of the season.
2. The data are shown in Tables 5 and 6.
3. What was learned in 1940.
a. If the soil is very dry during the period that corn should
be making its maximum growth, the plant roots cannot
take in much nitrogen, phosphate, or potash from the soil

Table 6. Average corn yields' obtained from quintuplicate plots in 1940
from various mixtures of fertilizers applied in the row and with and with-
out nitrogen broadcast and plowed under and with nitrogen side-dressed
about the 10th of July on four soils. Due to an extreme drought, moisture
was the limiting factor for most of the season. From July 3 to September
18, only 2.2 inches of rain fell on Clermont soil.

Fertilizer Treatment Miami
Clermont Vigo Crosby leam
silt loam silt loam silt loam sand
Nitrogen Mixed Nitrogen _
plowed fertilizers side-
un ler. added in dressed Bushels Pounds Bushels Pounds Bushels Pounds Bushels
lbs. per acre row2 pounds corn stover corn stover corn stover corn

Non' Non3 None 28.9 1200 34.6 1470 25.7 1510 15.4
None 0-12-12 None 23.1 1420 36.9 1940 32.1 1680 14.5
None 3-12-12 None 24.6 1750 42.2 2530 33.8 1990 19.5
None 3-12-12 20 28.4 1770 55.2 2610 44.8 2130 15.4

41 None None 33.3 1450 42.0 1550 29.1 2070 14.7
41 0-12-12 None 31.3 1560 47.3 2550 44.8 2210 11.8
41 3-12-12 None 32.8 2140 54.2 2740 47.6 2500 11.4
41 3-12-12 20 34.0 2160 59.0 3210 46.8 2490 13.1

82 None None 38.5 1550 47.7 1920 29.6 2100 10.8
82 0-12-12 None 43.0 2060 59.6 2280 49.4 2277 15.3
82 3-12-12 None 33.6 2410 63.1 3060 47.5 2540 10.3
82 3-12-12 20 35.6 2460 60.5 3480 49.4 2540 10.7

164 None None 32.7 1460 42.5 1670 40.1 2300 ...
164 0-12-12 None 37.8 2470 66.0 3040 55.5 2720 (1)
164 3-12-12 None 35.6 2520 62.8 3010 58.7 3060 ......
164 3-12-12 20 35.3 2620 63.5 2900 53.0 3050 ......

1643 None None 34.6 1600 41.7 1720 36.8 2000 ......
1643 0-12-12 None 39.0 2580 54.1 3210 56.5 2620 ......
1643 3-12-12 None 35.0 2700 57.8 4100 57.8 2920 ......
1643 3-12-12 20 36.6 2820 64.5 4080 56.8 2840 ......

Significant difference ...... 5.8 ...... 7.6 ...... 8.8 ......

1 Yields are in bushels per acre of No. 3 corn and field weight of stover at husking time.
2 600 pounds per acre on Clermo t, Vigo, and Crosby, a id 400 pounds per acre on Miami.
3 450 pounas of lime hydrate added to neutralize the acidity of ammorium sulfate used.
SThe experiment did not include these treatments.


when these nutrients have been placed near the surface or
in the row at the usual depth of about two inches. The
row placement helped the corn get started in the moist
period of late May and early June, but when the soil was
dry in July and early August, the phosphate and potash
remained in the dry soil and the nitrogen moved to th-
surface as nitrates, causing all of the fertilizer to be out
of reach of the roots which were reaching deeper into the
moist soil (see Table 6).
b. After a prolonged drought period nitrates will move up-
wards in the capillary soil moisture films to accumulate on
the surface in the top one-quarter inch crust. (See Figure
6.) Any slight rainfall will move the nitrates back into the
soil, but when the nitrates are on the surface of the dry
soil they are out of reach of the roots. (This helps to explain
why a summer shower after a long dry period refreshes the
vegetation so much-it's not only the water that helps but
also the nitrates which are moved back into the soil to the
feeding zones of the roots.)
c. When ammonium sulphate (the same would probably be
true of cyanamid or urea) was plowed under with organic
matter (straw), more of'the nitrogen remained in the am-
monium form than when the straw was omitted. (See Fig-
ure 7.) Figure 2 illustrates why the nitrogen in the ammo-
nium form is less movable in the soil than when it has been
oxidized to a nitrate form.
d. Side-dressing corn with ammonium sulphate was very ef-
fective where nitrogen was needed in 1939 when the rainfall
was adequate, but in dry 1940, the side-dressing treatment
did not work because the nitrogen did not get down to
the roots through the dry soil. Ammonium sulphate top-
dressed on the dry soil surface in early July had not changed
to nitrates 30 days later, and after 82 relatively dry days
later it was still in the topsoil. (See Figure 7.)
e. Plant tissue tests indicated that we would have to modify
our studies by placing the phosphate and potash, as well
as the nitrogen, deeper in the soil so as to have all the plant
food nutrients more accessible to the roots in dry periods.
(See Table 7.)
f. It is essential that the supply of nitrogen, phosphate, and
potash enter the plant in balances that are adequate. Table
8 and Figure 8 show that response to adding a needed
element is not obtained if another element is also deficient.
All the nutrients can be effective only when they are work-


PPM. of N Os NO1;
StO s e o .D 7 0 .5 . 0. .

July 17



in Inches


-PPM of I as WIO;

2 6 6 10 1Z is /6 /8 ) 22
Average Percent Moisture

PPM of N NOj u 6
t0 20 Js 40 o 60 o7 s0 o I0 August


I PRM. of N. s NOj -Per cent Morsrtu


2 2 4 8 10 /I 14 16 18 20 2
Ave'rge Percent Mo/dure




- 1.42

- 1.39

- 0.51

26-30 1.18

1-8 0.37

9-16 2.03

17 .00

18-31 .00





- .00

- 0.39

- .00

12-26 .00

- 2.05
- .00

- .00

- .00

- .00

Average Per cent Moijure

Figure 6.-The relationship between moisture and nitrate nitrogen
movement as shown by determinations made after dry periods (July 17
and August 6), and after a subsequent wetter period (August 30), on a
Vigo silt loam, Cloverdale 1940.
P.P.M. = parts per million. Multiply this figure by two to get equivalent
pounds per acre or 2,000,000 pounds of soil. (Weight of one
acre of soil to plow depth is 2,000,000 lbs.)
N = Nitrogen
NO3 = Nitrate Nitrogen



-Per cent Momifur



ri I
L". I

1000 bs. (NHl.J0. Top Dressed 22 Days Previous/j

.3 |155 r___4
2256 '46


Q. Not dampled Below q Inches


oo 1000 lbs.(N/4 SO, on Plow Sole

1 S , ,I!

'17 L__I __ I

// NHi Ind NO

r ? I

0 jo oo 900 oioo 10 120 10 60 30 0 o30 o o0 1o0 /0o
P.P.M of Total Nitren P.P. of N as NN* PPRM. of N as NO;
Figure 7.-The distribution of nitrate, ammonium, and organic nit-
rogen in the soil profile as affected by different placements of am-
monium sulfate, with and without organic matter. Vigo silt loam,
August 6, 1940. (82 days after treatment.)
P.P.M. = parts per million. Multiply this figure by two to get equivalent
pounds per acre or 2,000,000 pounds of soil. (Weight of one
acre of soil to plow depth is 2,000,000 lbs.)
Nitrogen = very slowly available to plants
NH+ = Nitrate Nitrogen (the mobile form)
NO3 = Ammonium Nitrogen (the non-mobile form)

Table 7. Corn yields on two soils in the dry season of 1940 where compari-
sons were made between plowing the fertilizer under and adding it in the
row and the influence of the placement upon the nutrients entering the
corn plants as indicated by plant tissue tests.

Bushels corn Plant tissue test of corn on
per acre Crosby silt loam, Aug. 1

Fertilizer1 and manner
of application Clermont Crosby
silt silt Nitrate Phos- Potash
loam loam phate

No fertilizer ................. 31.0 25.3 Low High High

N. broadcast and plowed under
P. and K. drilled in row ..... 40.2 46.8 High Low High

N. and K. broadcast and plowed
under, P. drilled in row...... 39.5 56.6 High Low High

N. and P. broadcast and plowed
under, K. drilled in row..... 35.0 55.0 High High Mediumn

N., P., and K. broadcast and
plowed under, no fertilizer in
the row................... 48.0 67.3 High High High

Rainfall between July 3 and
September 18 (inches)....... 2.2 5.6

1 N = 120 pounds nitrogen per ncre,
P = 120 pounds phosphate (P20 5) oer acre;
K = 120 pounds potash (K20) per acre.

ing together. The data in Table 8 shows how the Purdue
plant tissue tests (4) may be used in the diagnosis of plant
deficiencies. Note that the tests at the different periods in
the growth of the corn vary according to the demands of
the plants and the available supply.

C. 1941 Results
1. The weather was drought throughout the growing season and
extremely drought in midsummer. The rainfall was only
about one inch between the last of June and the middle of
2. The data are shown in Tables 9 and 10.
3. What was learned in 1941.
a. Where the soil was very deficient in nitrogen, phosphate,


and potash, the placing of 80 pounds N., 80 pounds P205
and 80 pounds K20 or the equivalent of 1,000 pounds of
8-8-8 fertilizer per acre in a band on the plow sole was a
very effective way to apply the fertilizer.
b. Placing the fertilizer in a band on the plow sole is better
than broadcasting the fertilizer and plowing it under. The
fertilizer placed in every other furrow in a band on the
plow sole is about as effective as placing it in each furrow.
(See Tables 11 and 12.)

Table 8. Results of plant tissue tests in corn where various rates of nitro-
gen and potassium fertilizers were used on a Crosby silt loam.

Material plowed
under in pounds Plant tissue test3
per acre' Yield Increases
Group bu hels above treat- July 10 August 1
nun.ber per acre ment No. 12
Nitrogen Potash
(N) (K20) N P K N P K
0 0 29.5 .......... O H H O H M
I 21 0 36.3 6.8 M H M 0 H L
42 0 49.4 19.9 H H L M H O
84 0 52.8 23.3 H H 0 H H 0

0 50 30.8 1.3 0 H H 0 H H
II 21 50 49.4 19.9 L H H 0 H H
42 50 56.2 26.1 H H H 0 H M
84 50 68.1 38.6 H H H H H M

0 100 33.8 4.3 0 H H 0 H H
III 21 100 50.1 20.6 L H H 0 H H
42 100 59.3 29.8 H H H 0 H H
84 100 71.8 42.3 H H H M H H

SAll plots received 300 pounds per acre of 0-16-4 at planting time.
2 Significant difference 3.2 bushels per acre.
3 O, one; L, low; M, medium; H, high Tests are an average of 6 plants from each of 5 replicates.

Attention is called to the following:
1. Phosphate was adequate in all plots; without the tissue tests
one would not be sure of this point.
2. In Group I, the tissue tests showed that nitrogen was the
first limiting element, but as the rate of application of nitrogen
is increased potassium becomes limiting. Without the tissue test
we might assume that the larger nitrogen treatments were not
very effective.


3. In Group II, where 100 pounds of muriate of potash was
plowed under with the nitrogen it is apparent that nitrogen has
become the limiting element except on the higher rates where the
adequacy of potash had become doubtful by August.
4. In Group III, where 200 pounds of muriate was used the
potash test shows an adequate supply and the yields then become
a function of the nitrogen application. Here it is interesting to
note that nitrogen had become limiting by August 1st and that
higher rates of application probably would have produced addi-
tional corn.
c. When fertilizers are applied on the plow sole, deep plowing
such as seven to nine inches is better than shallow plowing
such as three to four inches. (See Figure 11.)

Table 9. Average corn yields'from quadruple plots in 1941 from appli-
tions of nitrogen and muriate of potash broadcast on the ground and
plowed under with the previous crop residue on Indiana soils where 300
pounds of 0-16-4 was added in the row at planting time. The season was
extremely drought and the corn was badly injured.

Clermont silt loam

Materials plowed under








Bushels corn
per acre2

Vigo silt loam

Materials plowed under

Nitrogen Potash
(N) (K20)

Bushels corn
per acre

Significant difference... 7.4 ..................... 6.7

1 Yields are in bushels per acre of No 3 corn
2 The extreme drought and hot weather were factors that prevented the nutrients from being effective.

Table 10. Average corn yields obtained from quintuplicate plots in 1941 from various mixtures of fertilizers applied
in the row with and without nitrogen broadcast and plowed under and with nitrogen side-dressed about the 15th
of July on four soils. The season was extremely drought and moisture was the limiting factor affecting the yields.

Fertilizer treatment

plowed Mixed
under fertilizers
pounds added in
per acre row2

None None
None 0-12-12
None 3-12-12
None 3-12-12

41 None
41 0-12-12
41 3-12-12
41 3-12-12

82 None
82 0-12-12
82 3-12-12
82 3-12-12

123 None
123 0-12-12
123 3-12-12
123 3-12-12

Hybrid used...........

July 1 to Sept. 30.....






silt loam

North Vernon




96 0

None 21.9
20 29.3

....... .... 842

1941 5.98

Normal 11.39

Vigo silt loam






Ind. 613



Suckers per
80-foot row






silt loam









Crosby silty clay loam









Suckers per
80-foot row





1 Yields are in bushels per acre of No. 3 corn. 2 600 pounds per acre.


1 Yields are in bushels per acre of No. 3 corn.

2 600 pounds per acre.

d. When moisture becomes the first limiting factor (as in a
period of severe drought that started at about tasseling
time on the Crosby silt loam, Table 10), the fertilizers will
not increase the yields, even if the corn showed big differ-
ences in vegetative growth, because the bigger plants, stim-
ulated by the fertilizers, require more water and thus may
suffer more for the lack of it.
e. The corn will not suffer as much from a mild drought where
the fertilizers are placed deep as when placed shallow.
(See Figure 10.) When fertilizers are placed shallow they
are ineffective in dry periods.

D. 1942 Results
1. Planting was delayed by heavy spring rains. Cultivation was
also limited by wet soils. The season was characterized by ex-
cessive rains in the early growing period and ideal rains
throughout the later summer and fall. This was as excellent
a season to get information on the effects of abundant mois-
ture as 1940 and 1941 were to study the effects of inadequate
moisture. The wide variation in the amount and distribution
of rains in the four years of this study was most fortunate,
for as much valuable information was gained from the dry
years as from the wet ones.
2. The yield data are shown in Tables 13 and 14.
3. What was learned in 1942.
a. A starter fertilizer such as 100 pounds of an 0-12-12, 2-12-6,
or 3-12-12 added in the row will not increase the yield of
ear corn, in fact may reduce it, when used on land that
has a very low supply of available plant nutrients, as on
land that produces an average of about 30 or less bushels
of corn per acre. (See plots 1, 2, and 3 in Table 14 and
plots 1, 2, 3, 10, and 10s in Table 13.) This same amount
of row fertilizer, 100 pounds per acre, will produce great
increases in yields when used on land where they are suf-
ficient nutrients in the soil to carry the crop on to maturity.
This is true on soils where the yields are 35 bushels or more
per acre without fertilizers. (See plots 4, 5, 10, and 11 in
Table 14 and plots 4, 5, and 6 in Table 13.)
b. In a season of plenty of moisture, fertilizers containing
nitrogen will increase the weeds to a damaging extent when
this fertilizer is placed near the surface as from disking
in a fertilizer applied broadcast on plowed ground. (See
plot 9, Table 14.)
c. A starter fertilizer placed in the row will start the corn

off to a faster growth than if no starter fertilizer is used
and while weeds are stimulated as well as the corn, the
corn can be cultivated easier and the weeds covered easier
by raising the guard shields on the cultivator. This in-
creased start in the corn gives an advantage in yields only
if there is plenty of fertility in the soil to carry the crop
to a finish. If the fertility is not naturally in the soil, it
must be added.
d. Plant tissue tests have shown repeatedly that corn fertilized
in the row with 3-12-12 will contain a better nutrient
balance in the tissues until the plants are about 20 inches
high, and also will make a better early growth, than where
0-12-12 or no fertilizer is used.

Table 11. Effect of placing various fertilizer materials in a band on the
plow sole as compared to broadcasting it on the ground before plowing
under, and the effect of placing the phosphate and potash materials in
the row as compared to the plow sole on a Clermont silt loam in 1941 when
the rainfall was only 5.98 inches between July 1 and September 30. The
average rainfall for this period was 11.6 inches.

Materials plowed under Materials in the row2
N P20 K201 How plowed under P205 K20 per acre

0- 0- 0 0 0 21.9
40-40-40 Broadcast before.......... 0 0 30.2
40-40-40 Band every furrow........ 0 0 42.7
40-40-40 Band every second furrow. 0 0 44.2
40-40-40 Band every third furrow... 0 0 41.3

40- 0- 0 Broadcast before.......... 72 72 32.6
40- 0- 0 Band every furrow........ 72 72 38.8
40- 0- 0 Band every second furrow.. 72 72 39.0
40- 0- 0 Band every third furrow.... 72 72 41.3

1 All materialF are in pounds per acre on 1-10-acre unreplicated plots.
2 The row fertilizers are equivalent to 600 pounds per acre of 0-12-12.

e. A corn seedling will frequently show a shortage of phos-
phate in its tissues even with 600 pounds per acre of 0-12-12
added in the row at the side but will show adequate phos-
phate where 3-12-12 has been used. In such comparisons the
tissues were adequately supplied with nitrates and potash
at the time of the tests (corn about 18 to 20 inches high).
f. Corn plants that are growing in a soil very deficient in nitro-
gen, phosphate, and potash may show a shortage of phos-
phate in its tissues until the plant is about 12 inches high;




Table 12. A comparison of broadcasting the fertilizer on the ground be-
fore plowing with placing it on the plow sole in bands of varying distances
apart on a Vigo silt loam in 1941. The growing season was extremely
Materials plowed under; lbs. per acre Materials in row Bushels
N P205 K20 How plowed under P20s K20 per acre

0- 0- 0 0 0 12.2
80- 0- 0 Broadcast before.......... 0 0 27.2
80- 0- 0 Broadcast before.......... 80 80 60.0
0- 0- 0 80 80 23.7
80-80-801 Broadcast before.......... 0 0 56.7
80-80-80 Band every furrow........ 0 0 69.0
80-80-80 Band every second furrow.. 0 0 68.5
0-80-80 Broadcast before.......... 0 0 16.8
0-80-80 Band every furrow........ 0 0 20.4
0-80-80 Band every second furrow. 0 0 13.8
This treatment is equivalent to 800 pounds per acre of 10-10-10 on 1-10-acre unreplicated plots.

Figure 10.-This diagram shows how nitrogen, in the form of nitrates,
tends to move to the surface of soil with the soil moisture and is left
on the surface when the water evaporates. This occurs commonly in
midsummers in the Middle West where moderate droughts are frequent.
Where summer rains are more frequent as in the South this is not as
important because the rains will move the nitrates back into the soil
where the roots can absorb it. Where large amounts of plant food
nutrients are needed there is an advantage in placing the bulk of the
fertilizer in a band on the plow sole and in using a small amount of
starter fertilizer in the row near the seed, but not in contact with it.


then the nitrogen may become the first limiting nutrient
element and remain so until about maturity time, when
potash may show up as the first limiting factor.
g. Where a large amount of balanced plant food nutrients are
placed on the plow sole without a row starter fertilizer, the
corn will start growing poorly as if no fertilizer was used.
The corn thus fertilized will, however, make surprising in-
creases in its performance when the roots reach the deeply
placed fertilizer.
h. Where the fertilizer was placed in a band on the plow sole
there was less fixation of the phosphate than where the fer-
tilizer was broadcast and plowed under, as indicated by
tissue tests and yield comparisons.
i. When adequate nutrients were placed on the plow sole,
they were utilized more effectively where a starter (row)
fertilizer was applied than when it was omitted.

Stej undere" fertilization, as 600
Lb per acre of IO10-10 on plow sole
... lth deep ploin (7to s iches).

mWilU (rrsp,.t in I.rn-.)

Figure 11.-The response to fertilizers is greatly influenced by the
supply of moisture. In seasons of ideal rainfall the placement or kind
of nitrogen carrier does not matter much except that fertilizers placed
near the surface stimulate weed growth. In seasons of mild droughts
there is a distinct advantage in plowing deep when adding a heavy
application of fertilizer. In severe droughts water becomes the chief
factor that determines yields.


When Heavy Fertilizer Application is Used It Must be
Placed Deep
If the fertility of the soil is low so that more plant food nutrients
are needed to make a big yield of corn than are contained in
100 to 200 pounds of fertilizers applied per acre it is necessary
to place the extra fertilizers deep in the soil, as on the plow sole.
(See Figure 10.) There are serious objections to placing a heavy
application of fertilizer near or on the surface. In dry seasons the
plant roots cannot take up the nutrients from the fertilizer, and
in moist seasons the fertilizers will stimulate the growth of weeds
to such an extent that the weeds will seriously reduce the corn
yields. In this latter instance one might argue that the weeds
can be kept out. This is not an easy matter in wet seasons, for the
soil may be too wet for cultivation and under such conditions the
weeds may cause the greatest damage. When the fertilizer con-
tains considerable nitrogen as in a 1-1-1 ratio such as 10-10-10, the

Table 13. Average corn yields from quadruplicate plots in 1942 on Vigo
silt loam, as related to various row and plow-under fertilizer treatments.

Bulk of the fertilizer


0- 8- 8
4- 8- 8
8- 8- 8
16- 8- 8
8- 0- 8
8- 8- 0
8- 8- 8

per acre





On plow-sole
On plow-sole
On plow-sole
On plow-sole
On plow-sole
On plow-sole
On plow-sole
and plowed

Bushels per acre

No row



100 0-12-12
in row
400 3-12-12
in row

Row fertilizer
100 lbs. 3-12-12







Significant difference ....................... 10.8 10.8

The season was characterized by excessive rainfall.
(Credit is due 0 W Luetkemeier, Graduate Assistant, for this data.)


stimulation to the growth of weeds from the fertilizers placed near
the surface is greatly increased over that of a fertilizer that con-
tains no nitrogen as in an 0-12-12 or 0-20-20 mixture. When a
high nitrogen fertilizer as 10-10-10 is placed deep, the weeds are
not stimulated to grow fast for three or four weeks and in this
period the corn with a row starter fertilizer, as 100 to 200 pounds
per acre of a 3-12-12, gets a jump ahead of the weeds. Cultivation
can then control the weeds more easily.
The effects of various amounts of rainfall or drought on shallow
and deep plowing whether fertilizers are used or not are shown
in Figure 11.

What Should the Plow-Under Fertilizer Be?
Mixtures of 10-10-10 and 8-8-8, as well as equivalent amounts
of the single plant food nutrients were used in this study. In
some cases, as perhaps for tomatoes, a 5-10-5 or 5-10-10 may be
desired. A 5-10-20 may have advantages for potatoes and corn
on dark colored soils.
Where large quantities, as 100 pounds of N, 200 pounds, P205,
and 200 pounds K20 per acre or variations of these are needed,
the grower can use the straight plant nutrient carriers if there is
a justifiable differential in the costs per unit of nutrient between
that of the mixed fertilizers and the unmixed materials. In this
case there is the inconvenience and cost of extra handling. Farm-
ers must study the comparative costs per unit of plant food nu-
trients in mixed and straight goods and use the material that is
most economical.

Fertilizers Placed on Plow Sole Have Advantages Over
Those Broadcast and Plowed Under
The results from both the dry 1941 and wet 1942 seasons
show that where heavy fertilization is used, there is a big advan-
tage in placing the fertilizer in a band on the plow sole as com-
pared to broadcasting it on the ground and plowing it under.
The latter procedure places the fertilizers both high and low, thus
losing part of the advantage of deep placement; also, this pro-
cedure mixes the fertilizer materials more with the soil than
does the band placement. The mixing of the fertilizer and the
soil causes a decrease in availability of the phosphate in the
fertilizer by fixation with the soil. The band-placement on the
plow sole gives the phosphate a localized placement that will re-
duce the rate and amount of phosphate fixation. The organic
matter plowed under is acted upon by micro-organisms which
use the nutrients from the fertilizers. This converts some of the


nutrients, particularly the nitrogen and probably the phosphates,
into organic forms to be made available later. There is also an
advantage in placing potash deep as it is not subject to the rapid
wetting and drying action which tends to fix potash in an un-
available form.

Table 14. Average corn yields from quadruplicate plots in 1942 on Vigo
silt loam as related to various plow-under, broadcast, and row fertilizer

Bulk of fertilizer Bushels per acre

Plot No row fertilizer Row
num- Lbs. fertilizer
ber Mixture per How applied Corrected (starter)
acre Actual for frost 150 lbs.
factor' 2-12-6

1 .......... 0 .................... 17 .0 18 .4 18 .2
On plow sole in bands
2 0-10-10 1000 14" apart.......... 20.9 23.3 18.2
3 5-10-10 1000 14" apart.......... 37.5 39.7 39.7
4 10-10-10 1000 14" apart.......... 40.6 45.1 54.0
5 15-10-10 1000 14" apart.......... 39.6 43.8 55.7
6 10-10-10 500 14" apart.......... 28.9 32.6 37.2
7 10-10-10 500 28" apart.......... 27.9 31.0 38.9
8 10-10-10 500 Broadcast and plowed
under............. 22.2 23.7 21.0
9 10-10-10 500 Broadcast after plow-
ing and disked in... 14.6 15.0 16.4
10 10-10-10 1000 Broadcast and plowed
under............. 33.8 37.2 45.7
On plow sole in bands
11 10-10-10 1500 14" apart.......... 50.5 56.6 69.7
12 10-10-10 500
2-12- 6 150 14" apart.......... 34.7 38.1 42.6

13 10-10-10 500 In row .............. ........ ........ 30.9

14 .......... 0 ...................... 150poundsof
0-12-6 in row.. 20.6

Significant difference ........................... 7.... .... 7.8

The rainfall was excessive in spring and early summer
SCorn was planted lare (June 3) and killed by frost very early (September 24) The corn with starter (row)
ertiliier did not quite mature and the corn without starter fertilizer lacked even more of maturing as shown by the
fact that at fro.t it contained at least 8 per cent more moisture than the corn with starter fertlli:er Using unpub
listed data of S. R. Miles, Agronomy Department, Purdue University, the yields from treatments without starter
fertilizer were adjusted so that the differences due to starter are very probably more nearly what they would have
been if frost had held off until all corn was mature

Fertilizer Attachment for Adding Fertilizer on the Plow Sole
A fertilizer distributing attachment used in these studies was
designed by Professor R. H. Wileman of the Purdue Agricultural
Engineering Department (see Figure 12). Using this original
design, the International Harvester Company made up a few of
these attachments.

If Nitrogen-Carrying Fertilizers are Applied Broadcast and
Plowed Under, Do Not Delay the Plowing
In some instances farmers may need to use the less desirable
method of broadcasting the fertilizer containing nitrogen on the
ground and plowing it under. In this case use a grain drill with a
fertilizer attachment and apply the fertilizer in drill bands. Since
there is an advantage in having the nitrogen that is plowed under
in an ammonium form, it is important where ammonium sulphate
or cyanamid is used, to plow immediately after the material is put
on the ground. If the nitrogen-carrying fertilizers are not plowed
under at once, the ammonium nitrogen will be converted to ni-
trate forms. This is objectionable, for the nitrates are easily moved
to the surface in dry periods. There is, of course, greater danger
of loss of nitrates by leaching and in run-off waters. Nitrogen-
carrying fertilizers applied long before plowing under will be
used up to a large extent by grasses and weeds, and thus be less
effective in feeding the corn. We have observed this particularly
on hay meadows where the timothy growth was so greatly increased
from application of 500 or 1,000 pounds per acre of 10-10-10
broadcast 30 days or more before plowing under, that the in-
creased carbonaceous timothy growth made the corn starve more
for nitrogen than if none had been added.

Residual Effects from Heavy Fertilization
Table 15 is shown to indicate the residual effect obtained in
1942 from the heavy fertilization in 1941 where unfertilized soy-
beans followed the fertilized corn. It is evident that the residual
effect may be great. It has been observed that the residual effect
is greatest where 'the fertilized crop failed to make big increases
in yields, as from dry weather, and then to use up the nutrients
added. Where 84 pounds per acre of nitrogen along with phos-
phate and potash had been used for corn in 1938 and again in
1939 on the same Crosby silt loam, the oats yield in 1940 was
109 bushels per acre, and 50 bushels per acre where only the
phosphate and potash had been used without the nitrogen. Where
the fertilized crop made big yield increases and used up much of
the added nutrients the residual yields of crops were not as great.

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