• TABLE OF CONTENTS
HIDE
 Cover
 Half Title
 Frontispiece
 Title Page
 Preface
 The farmers' contribution
 Table of Contents
 The plowman
 Part I
 Part II






Group Title: New Series Bulletin - State of Florida, Department of Agriculture ; no. 105
Title: Science in agriculture
CITATION THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00002886/00001
 Material Information
Title: Science in agriculture
Series Title: <Bulletin> New Series
Physical Description: xii, 216 p. : ill. (some col.) ; 20 cm.
Language: English
Creator: Brooks, T. J ( Thomas Joseph ), b. 1870
Florida -- Dept. of Agriculture
Publisher: State of Florida, Dept. of Agriculture
Place of Publication: Tallahassee <Fla.>
Publication Date: c1940
 Subjects
Subject: Agriculture -- Florida   ( lcsh )
Farm produce -- Florida   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Thos. Jos. Brooks.
General Note: "March, 1941."
 Record Information
Bibliographic ID: UF00002886
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: aleph - 002456352
oclc - 41556056
notis - AMG1678
 Related Items
Other version: Alternate version (PALMM)
PALMM Version

Table of Contents
    Cover
        Cover
    Half Title
        Half Title
    Frontispiece
        Frontispiece
    Title Page
        Title Page 1
        Title Page 2
    Preface
        Page vii
    The farmers' contribution
        Page viii
    Table of Contents
        Page ix
        Page x
        Page xi
    The plowman
        Page xii
    Part I
        The business of farming
            Page 1
            Page 2
            Page 3
            Page 4
        Farm man-power production
            Page 5
            Page 6
            Page 7
            Page 8
        The story of farm machinery
            Page 9
            Page 10
            Page 11
            Page 12
            Page 13
            Page 14
        Electricity on the farm
            Page 15
            Page 16
            Page 17
            Page 18
        Story of the earth's soils
            Page 19
            Page 20
            Page 21
            Page 22
            Page 23
            Page 24
            Page 25
            Page 26
        Soil waste
            Page 27
            Page 28
            Page 29
            Page 30
            Page 31
            Page 32
        Soil-building plants
            Page 33
            Page 34
            Page 35
            Page 36
        Conservation of soils
            Page 37
            Page 38
            Page 39
            Page 40
        Soils and fertilizers
            Page 41
            Page 42
            Page 43
            Page 44
            Page 45
            Page 46
            Page 47
            Page 48
            Page 49
            Page 50
            Page 51
            Page 52
            Page 53
            Page 54
        Air and life
            Page 55
            Page 56
            Page 57
            Page 58
        Plant and animal life
            Page 59
            Page 60
            Page 61
            Page 62
            Page 63
            Page 64
            Page 65
            Page 66
            Page 67
            Page 68
            Page 69
            Page 70
            Page 71
            Page 72
            Page 73
            Page 74
            Page 75
            Page 76
            Page 77
            Page 78
        Fungi
            Page 79
            Page 80
            Page 81
            Page 82
        Filterable viruses
            Page 83
            Page 84
            Page 85
            Page 86
        Food and health
            Page 87
            Page 88
            Page 89
            Page 90
            Page 91
            Page 92
        Changing rural psychology
            Page 93
            Page 94
            Page 95
            Page 96
            Page 97
            Page 98
    Part II
        The story of native and immigrant crops
            Page 99
            Page 100
            Page 101
            Page 102
        The story of life cycles
            Page 103
            Page 104
            Page 105
            Page 106
        Story of man's struggle with insects
            Page 107
            Page 108
            Page 109
            Page 110
        Bird life and man
            Page 111
            Page 112
            Page 113
            Page 114
            Page 115
            Page 116
            Page 117
            Page 118
        The story of cotton
            Page 119
            Page 120
            Page 121
            Page 122
            Page 123
            Page 124
            Page 125
            Page 126
            Page 126a
        The story of wheat
            Page 127
            Page 128
            Page 129
            Page 130
        The story of maize (Indian corn)
            Page 131
            Page 132
            Page 133
            Page 134
        The story of rice
            Page 135
            Page 136
        The story of root crops
            Page 137
            Page 138
            Page 139
            Page 140
            Page 141
            Page 142
            Page 143
            Page 144
        The story of sugarcane
            Page 145
            Page 146
            Page 147
            Page 148
        The story of beans
            Page 149
            Page 150
            Page 151
            Page 152
            Page 153
            Page 154
            Page 154a
        The story of fruit-growing
            Page 155
            Page 156
            Page 157
            Page 158
            Page 159
            Page 160
            Page 161
            Page 162
            Page 163
            Page 164
            Page 165
            Page 166
            Page 167
            Page 168
        The story of berries
            Page 169
            Page 170
            Page 171
            Page 172
            Page 173
            Page 174
        The story of nuts
            Page 175
            Page 176
            Page 177
            Page 178
            Page 179
            Page 180
        The story of grapes
            Page 181
            Page 182
        Pasture and forage crops
            Page 183
            Page 184
            Page 185
            Page 186
            Page 187
            Page 188
        The story of coffee
            Page 189
            Page 190
        The story of tea
            Page 191
            Page 192
            Page 193
            Page 194
            Page 195
            Page 196
        The story of tobacco
            Page 197
            Page 198
            Page 199
            Page 200
        The story of domestic animals
            Page 201
            Page 202
            Page 203
            Page 204
            Page 205
            Page 206
            Page 207
            Page 208
            Page 209
            Page 210
            Page 211
            Page 212
            Page 213
            Page 214
            Page 215
            Page 216
Full Text




in AGRICULTURE


THOSE. Jos. BROOKS


STATE OF FLORIDA
Department of Agriculture
NATHAN MAYO, Commissioner







SCIENCE IN AGRICULTURE







SCIENCE IN

AGRICULTURE








By Thos. Jos. Brooks
Formerly
Professor of Rural Economics
in Mississippi State College
Author of
"The March of Mind"



Copyright, 1940
By T. J. Brooks









First Edition
All Rights Reserved









PREFACE
Any systematized arrangement of facts is science. There
are as many sciences as there are distinct branches of knowl-
edge. The interrelation of some branches of science is so
intimate that a thorough knowledge of one is impossible with-
out a knowledge of the others. A college degree in science
means a certain accomplishment in a certain line of studies
marked out by a particular college. No science is complete.
There is more to know about everything.
In this volume we have essayed to give a synopsis of facts
on the various themes discussed. Every one should know
something of the sciences that vitally touch the life of the
millions. In our modern complex civilization we are sur-
rounded on all sides by the implements brought into existence
by science and without which the whole structure of human
institutions would crumble. To the extent that mankind mas-
ters his environment and his interrelationship will he hold to
what he has accomplished and make further progress. The
domestication of plants and animals by man marked the
beginning of what we term civilization.
Agricultural information should be possessed by rural stu-
dents and rural life should be better understood by the students
of the urban schools.
T. I. BROOKS.









THE FARMERS' CONTRIBUTION
In ancient times the farmers gave
A hungry world the staff of life;
And strove humanity to save
In all its labors, toil and strife.
In all the thousand years that sped
Through Middle Ages rent with wars,
The farmers saw that man was fed,
And kept the watch neathh sun and stars.
In modern times 'mid constant change
In all the works of striving man,
When progress works its wonders strange,
The farmers by their mission stand.
They answer signals far and wide,
Yet hold their hands upon the plow
Their harvests must keep man supplied
With all the gifts the soils allow.
No frugal meal of milk and bread
But comes from farmers' sweat and toil;
No bounteous board is ever spread
But comes from plowman's skill and moil.
The cities great where millions dwell,
With looms and lathes neathh towering spires-
The burdens of the farmers swell-
They look to them till life expires.
Beneath this burden they must stand
Or civilization's banner fall;
No matter what betides the land
The farmer folk must feed them all.
T. J. BROOKS.
Tallahassee.








I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
XIII.
XIV.
XV.


CONTENTS
Part I.

The Business of Farming .
Farm Man-Power Production
The Story of Farm Machinery
Electricity on the Farm
Story of the Earth's Soils
Soil Waste
Soil-Building Plants
Conservation of Soils
Soils and Fertilizers
Air and Life
Plant and Animal Life
Fungi
Filterable Viruses
Food and Health
Changing Rural Psychology


Page
1
5
9
15
19
27
33
37
41
55
59
79
83
87
93


ILLUSTRATIONS
Part L

Preparing the Soil for Planting
Soil Erosion .
Wind Erosion
Federal Government Report
Crotalaria
Cassava .
Japanese Beetles .
A Balanced Diet for Health and Longevity
Rural and Urban Life Combined


Page
21
23
28
32
35
40
78
92
98




CONTENTS
Part II.
XVI. The Story of Native and Immigrant Crops .
XVII. The Story of Life Cycles
XVIII. Story of Man's Struggle with Insects
XIX. Bird Life and Man
XX. The Story of Cotton
XXI. The Story of Wheat .
XXII. The Story of Maize .
XXIII. The Story of Rice
XXIV. The Story of Root Crops .
XXV. The Story of Sugarcane
XXVI. The Story of Beans .
XXVII. The Story of Fruit-Growing
XXVIII. The Story of Berries
XXIX. The Story of Nuts
XXX. The Story of Grapes
XXXI. Pasture and Forage Crops
XXXII. The Story of Coffee .
XXXIII. The Story of Tea
XXXIV. The Story of Tobacco
XXXV. The Story of Domestic Animals


ILLUSTRATIONS
Part I.
Planting Cotton .
Harvesting Wheat in the Northwest
Corn Field
Papaya .
Sugarcane Growing
Apiary .
Bean Picking Time-Field of Cabbage
Fruit Groves and Irrigation
Apples in the Northwest
Pears and Peaches in Blossom
English Walnut Grove
Cutting and Loading Hay
Tea Plantation--Coffee Bush.
Tobacco Field
A Herd of Herefords
Beef Cattle .
Fine Cattle and Swine
Sheep on Pasture-Peanuts


Page
S99
103
S107
111
119
127
131
135
137
145
149
S155
169
175
181
183
189
191
197
201


Page
. 121
.129
133
144
147
148
151
154
158
S 168
179
187
193
. 196
202
S 203
S205
207









THE PLOWMAN
No longer "The Man with the Hoe" is he
Who tills the soil. In his place, in this day,
Is the Plowman who looks the world in the
Face unafraid. Forged steel turns the stubborn
Glebe. Tractors do his bidding when he calls;
Sunshine and showers come with the seasons;
And nature laughs a bountiful harvest
To feed the millions of the earth.

No longer "bowed by the weight of centuries,
The emptiness of ages in his face,"
He mounts his iron steed, commands, and Lo!
Renders lighter the burdens of the world.
Responsive to rapture and despair-
As are the royal, the rulers and lords-
He claims dominion o'er land and sea, traces
The stars and searches for power.

"The creature dreamed by Him who shaped the suns
And pillared the firmament with light";
Familiar with nature's wondrous secrets,
"Conversant with Plato and Pleiades";
Last fruitage of time's many tragedies
And upward climb of turbulent mankind;
The future must reckon with this Plowman,
Who holds his hand on the throttle of the world.
T. J. Brooks.





Part I


I
THE BUSINESS OF FARMING

FARMING is a business the same as any
other of the major activities of man. Com-
mercial and financial businesses have been
more spectacular than farming and have
rather turned the public mind to them as the
real business vocations of modern life. Any
occupation that requires intelligence, time,
energy, diligence and forethought is a busi-
ness. Farming requires these things of a high
order. Every business known has its incom-
petents and its failures. Farming has its
share of these.
Students of agriculture have treated dif-
ferent phases of it under special headings:
Agronomy, Farm Management, Agricultural
Economics, etc. These are very closely allied
and even overlap. They are all parts of the
broad subject of Agriculture.
Agronomy is the scientific management of
land. Farm Management is science of coor-
dinating the use of capital, labor, machinery,
power, and the commercial phase of market-
[1]




SCIENCE IN AGRICULTURE
ing. Agricultural Economics is rather inclu-
sive as it takes into consideration those above
mentioned and adds the philosophy of the
farming industry as it relates to other kinds
of business.
The improper use of land has been a seri-
ous fault since man first attempted to till the
soil. Without a knowledge of lands and
crops, and a concern about the future fertility
of the soil, the depletion of land is sure to
bring poverty and deterioration of all that go
to support human institutions. This is proved
in the story of old civilizations. Agronomy
concerns the conservation of soil, economic
crop production, farm engineering and the
problem of coping with the elements.
Farm Management is largely dependent
on the personal equasion; the adaptability,
aptitude, frugality and thriftiness of the one
in charge. Blueprint directions followed me-
chanically are better than no system at all
but nothing takes the place of the dexterity
acquired by long practice. More farmers fail
because of an unbalanced condition in the
investment and of idle horses and machinery
than from crop failures. The lack of proper
[2]




THE BUSINESS OF FARMING
functioning of labor on the farm is a drain on
its resources. Men brought up on the farm
learn to handle farm machinery and to take
the place of a hired mechanic in the operation
of machines and tools that it is difficult for
men reared in cities to acquire. On the other
hand a man inured to hard labor on the farm
will find it difficult to adapt himself to the work
done by the professional men of the cities.
The farmer should keep books on himself.
He should not allow his soil to be depleted or
his ledger will show profits when there are
none. Too many farms are mined till worth-
less and the owner thought he was making
profits.
Speculative profits are seldom shown in
farming but there is no vocation that offers so
safe and sure a living to the family as farm-
ing, when carried on with reasonable dili-
gence.
Agricultural Economics must use all fac-
tors connected with farming. It includes not
only the subjects here mentioned but such
subjects as finance, credit, tenantry, absentee
ownership of land, marketing, cooperation,
social conditions and the effect of laws on the
[3]





SCIENCE IN AGRICULTURE
farming industry. Each of these subjects
requires special treatment and elaboration.
The surface of the earth used for agricul-
ture exceeds that of all other of man's indus-
tries. The amount invested and the number
employed exceed that of any other branch of
man's occupations. The absolute indispen-
sability of the vocation marks it as the first
essential in civilized society. As the source
of support of the teeming millions of the earth
it stands pre-eminent in all of the works of
mankind.


[4]







FARM MAN-POWER PRODUCTION

MAN-POWER production is the basis of
economics. Inventions have raised effi-
ciency in production enormously in some
lines and but little in others. Perhaps it is
greater in manufacturing than in any other
line of industry. Agricultural machinery has
vastly increased man-power in harvesting
wheat but not in gathering corn or cotton.
Horseshoes are now made by machinery but
they still are nailed in the horse's hoof by the
same old method. Fruit trees are cultivated
by machinery but the fruit itself must be gath-
ered by hand. Highly specialized farming
requires much more man-power per quantity
of production than does general farming.
Values per acre in trucking, tobacco and fruit
growing are higher than in general farming.
Too much stress has been placed on acre-
production and not enough on man-power
production. Productivity of soil and acreage
cultivation determine man-production. A
one-man crop in some things is from two to
five acres. A one-man crop in some instances
[s]





SCIENCE IN AGRICULTURE
is two hundred acres. The amount of money
involved is another factor in comparing dif-
ferent kinds of farming. The capital required
in one instance might be no more than a few
hundred dollars and in another instance sev-
eral thousand dollars. The amount that can
be produced of a crop is of very little conse-
quence. The value of the crop produced per
hand is the important consideration.
Naturally a man prefers to farm where he
can produce more values per hand and with
the least possible outlay of investment, pro-
vided climate and general surroundings are
agreeable. But there is an element in the
equasion which is often overlooked-the
adaptability of the man to the particular kind
of farming that is to be done. A man may
make a success of one kind of farming and a
failure of another kind in the same commun-
ity. Farming is no different from all other
vocations in that it is largely psychologic as
well as economic.
Even man-power production in values is
not the whole story. The expense involved
in the production has to be reckoned with.
Each different crop and each kind of soil
[6]




FARM MAN-POWER PRODUCTION
and the whims of the seasons have something
to say in the cost of production problem. If a
man is growing celery the requirements per
acre in drainage and irrigation, preparation
of soil, fertilization, etc., are considerable-
much more than ordinary field crops. Next is
the limitation of acreage that can be cared
for by one person. The expenses attached to
gathering and preparing for the market, in-
cluding pre-cooling, all have to be added to
the cost of production. Man-power produc-
tion is quite low in quantity-value may or
may not be satisfactory.
Much the same limitations as to expense in
production, handling and acreage per hand
applies to the growing of tobacco. In cotton
it is different. More acres can be cultivated,
not so much expense in preparation and cul-
tivation, but the gathering is tedious. No one
can gather as much as he can grow. Corn is
still different. More acreage can be culti-
vated, on practically the same plowing but
with much less hoeing. A man can gather
all he can grow.
With wheat the difference is still greater.
More acreage can be grown, no cultivation
[7]




SCIENCE IN AGRICULTURE
other than that required for the sowing, har-
vesting is by machinery, only a few months
in the year is required for the sowing and the
reaping. Large acreage of land is needed,
heavy investment in land, in sowing and har-
vesting machinery and storage is out of the
question in the main wheat belts; that func-
tion is performed by the large elevators usu-
ally not owned by the farmers. This kind of
farming represents man-power production
at its highest, both in quantity and in values-
but cost of investment is necessary to be a
self-dependent wheat farmer, with live stock
and soil-improving crops to alternate with
wheat, render the man-power profit-earning
not so spectacular.
When one calculates the possibilities of
farming in any country and in the growing
of any crop he must take into consideration
all the factors before he can reach a correct
conclusion, not the least of which the prob-
abilities in price fluctuations of the crops to
be grown. After all it is man-power gain that
is wanted.


[8]






THE STORY OF FARM MACHINERY
MODERN CITIES are built on farm ma-
chinery. But for the improved imple-
ments of agriculture 17 farmers could not sup-
port themselves and 83 others who live in
cities. At the beginning of this government
70% of the people lived on farms; now 70%
live off farms-due to farm machinery.
Ancient peoples had crude implements
and lived crudely. The modern steel or
chilled plow was unknown till a hundred
years ago! Wrought iron and steel pointed
plows with wooden mould boards were the
dependence for cultivating the soil. The trek
from country to city was made necessary to
escape overproduction on the farm and pro-
vide workers for the mass-production of the
vast array of industries that sprung up in
cities, at mines and in the transportation
business.
Steel had been in use for centuries but little
had been used in the making of farm imple-
ments. The plow was originally made of
wood. It was drawn by oxen, horses, or
[9]




SCIENCE IN AGRICULTURE



Al
ri ,.


other draft animals; in some instances by
men and even by women. The steel plow
did not come into use till the first quarter of
[10]




THE STORY OF FARM MACHINERY





I" I










the nineteenth century. First the wrought
iron made by blacksmiths, then steel points
with wooden mould board, then cast point
and mould board, then all steel and then
chilled turning plows. All along with these
changes the other types of plows were steel:
the bull-tongue, the shovel, the sweep types
were in vogue; each on a single stock. Then
came the cultivators of types galore-walk-
ing and riding, pulled by horses and then by
tractors.
Different types of soil demanded different
[11]




SCIENCE IN AGRICULTURE


//
S... -.-,


I / )'j


..... --l -,t -



kinds of plows, both as to shape and material.
In the pioneer days of this country most lands
had to be cleared of timber before they could
be cultivated. This left the soil full of roots
and very difficult to plow. The first plow used
was usually the bull-tongue with a coulter
before it. The coulter was to cut small roots
and the plow was narrow and long, and
turned the soil both ways. The turning plow
was most in use after the ground was first
broken.
Sandy loam soils are easiest to plow. The
[ 12]




THE STORY OF FARM MACHINERY
grit causes the dirt to slide over the surface of
the plow and "scour" the surface continually
and keep it bright. The friction is less than
when the dirt clogs and sticks to the metal.
Tough clays do not scour well and the black
soils of the western prairies without sand is
the most impossible to make scour. No plow
stays bright in these soils. However it is of a
texture that keeps it loose after being plowed
in the early winter.
Among the notable inventors of plows may
be mentioned John Deere, B. F. Avery, James
Oliver, John Lane, Leonard Andrews of the


'vi Y


_~c~-- --izi


[13]




SCIENCE IN AGRICULTURE


V


turning plow. The leading inventors of reap-
ers, binders and harvesters are Obed Hus-
sey, Cyrus McCormick, William Deering,
John Heath, John Appleby, Osborn and the
March brothers.
The United States has always led the world
in the invention and manufacture of farm ma-
chinery. It has reached the enormous sum
of $450,000,000 worth annually. Some 250
factories employ 70,000 workers who are paid
$80,000,000 annually.


[14]





IV


ELECTRICITY ON THE FARM

PERHAPS electricity is the most puzzling
source of power in inanimate nature. The
first acquaintance of man with this material
agency was in the thunderstorm. It was not
till 1650 that its name came into use. Not till
1733 was it discovered that its manifestations
indicated that there were two kinds-positive
and negative. Its quality of attracting one
object by another when one object is "charg-
ed" is called magnetism-this is known as
static electricity. When in motion it is termed
dynamic or current electricity.
Some of the remarkable properties of elec-
tricity are: to pass through metallic sub-
stances to magnetize iron and steel; to gen-
erate and induce current in a neighboring
circuit by its own variation; and to heat con-
ductors of high resistance to incandescence.
The mastery of this titanic force is of quite
recent origin. No power in nature is so ever
present and inexhaustible as electricity.
From the crude beginning of electric cells in
batteries and lightning rods to the present
[15]




SCIENCE IN AGRICULTURE


enormous dynamos, propelled by steam or
water power, is a story of achievement that
is startling to the imagination.
What is it in the field of power utilization
that electricity does not enter as a factor? We
talk across continents with it, we run locomo-
tives, autos, and planes, trailers, and fac-
tories; we cook, light streets and homes, and
preserve food by its use. The last industry
that is being transformed by electricity is
farming.
As expressed by Lee VanDerlinden:
"Consider electricity, the history of which
closely parallels the application of other types
of power and machinery used on farms of this
country. For example, consider the history
of farm tractors. When first developed in
sizes that could be profitably used on the
general type of farm, the primary purpose
was for spring and fall plowing. The remain-
der of the year it stood idle. However, soon
farmers began using it for other mobile and
stationary power needs, until some uses un-
dreamed of 20 years ago are commonplace
today.
"Electric energy for power on farms has
[16]




ELECTRICITY ON THE FARM
already passed through the initial stage of a
few uses as lights and one or two appliances.
Today, progressive farmers are putting it to
work pumping water for livestock, irrigation
and household needs, cooking their meals,
lengthening the day through proper lighting,
milking, cooling milk and other perishable
food products, brooding chicks, filling the
silo, elevating grain, unloading hay, grind-
ing grain and many other such labor-saving
uses, some of which were not considered pos-
sible a decade ago.
"Manufacturers in the past have followed
the lead of the engineers and made equip-
ment to be operated by tractors or motors of
high horsepower rating. Now they have real-
ized that the efficient farmer has a need for
equipment to be operated by 5 or 71/2 horse-
power motors and are beginning to fill this
want. Grinders, insilage cutters, shredders,
etc., that formerly required large tractors for
operation, are now available to do the same
job cheaper with 5 horsepower electric mo-
tors."
With farming being put on a more scien-
tific basis and the substitution of mechanical
[17]




SCIENCE IN AGRICULTURE
power for horses and hand labor the matter
of costs becomes very apparent. The effi-
ciency of electric motors and the low cost of
electric energy will make this type of power
very desirable for many of the tasks found on
every farm.
Electricity brings with it convenience,
health, peace and contentment-on the farm.
When farm homes are located close enough
to power lines it is quite possible to equip sta-
tionary machinery to do the household
drudgery-washing, sawing wood, turning
lathes, etc., and to light the home and cook
with electricity.


[18]







STORY OF THE EARTH'S SOILS
DESTINY OF CIVILIZATION IN LAND FERTILITY
SOIL might be said to be the surface of the
earth not under water. But from the
standpoint of economics, soil is that part of
the earth's surface capable of producing the
requirements for vegetable and animal life.
This definition excludes a great portion of the
land surface of the earth. Very little of the
two frigid zones qualify under this head.
Much of the temperate and tropical zones
cannot be included. Bare mountains, bare
rocks, deserts inaccessible to irrigation, gla-
ciers, lands once fertile but ruined by erosion,
all these must be subtracted from the real
soil areas.
A planet without soil, water, air, and sun-
rays, arranged in proper proportion, would
be a dead planet. Apparently there are
many of them in space. Therefore there is
nothing of more importance than these com-
plementary forces of nature. Especially is
this true since the population of the continents
[19]




SCIENCE IN AGRICULTURE
and isles of the sea has become a problem of
sustenance.
Plant-food content, temperature, moisture,
chemical, and mechanical condition of the
soil all enter into the equation of the availabil-
ity and value of soil from a production stand-
point. The same kind of soils in different
zones mean different crops, different seasons,
and different methods of cultivation. The
desirability of location also goes far toward
determining the trade value of land.
Geologically speaking, soils are made up
of ground and pulverized minerals that hold
intact soluble plant-food elements which
need moisture, air, and sunshine to germi-
nate seed and produce growth. These sur-
face materials are easily washed from their
position by heavy rains and the lands thus
washed become sterile and barren as a
result. Improvident handling of soils has
wrought havoc in many lands. Billions of
tons of fertile soils have been washed into the
rivers and into the seas. Countries once fer-
tile and supporting a teeming population
have become so impoverished that only a
semblance of their past productivity remains.
[20]














































Preparing the Soil for Planting




SCIENCE IN AGRICULTURE
We may cite such flagrant examples as Baby-
lonia, Assyria, Greece, the peninsular part
of Italy, Palestine-once a "land flowing with
milk and honey"-much of China, European
Russia, and India.
We have been repeating the story in the
United States. The Southeastern section is
scarred worse than other areas. Poverty of
soils brings poverty of people, with all that
poverty means to humanity. Even when soils
produce a living quantity, they do not always
contain all the elements that are needed to
make a well-balanced ration for those who
depend on their products for food. Plants
will grow when some of the natural elements
are lacking, and animal life will exist when
some of the required food elements are lack-
ing. But, when this is the case, there is a lack
of vitality and endurance that would come
of a proper diet.
This earth has on it two billion people to
be fed, clothed, and sheltered; these must
come from the soil. The areas of land from
which these things must come is limited. The
waters of the land and the sea furnish an
auxiliary supply in the form of sea-foods, but
[22]














































Soil Erosion




SCIENCE IN AGRICULTURE
mighty few could exist on sea products only.
About one-fifth of the earth is covered by
ice-some land and some water. The water
areas together cover 139,000,000 square
miles. The land areas cover 58,000,000
square miles. When we deduct the unusable
lands the number of acres possible to use
shrinks to a bare 30,000,000 square miles.
Only 1 per cent of this is in actual productive
use.
In continental United States we have 2,-
900,000 square miles. Only 1,000,000 square
miles of this can ever be utilized by man for
his subsistence. Our actual present culti-
vated acreage is one million acres for each
day in the year-365,000,000.
The acreage devoted to the production of
food in the United States is approximately
290,000,000. Acreage devoted to the produc-
lion of non-food products-such as cotton,
wool, tobacco, flax, etc.-is in round numbers
25,000,000 acres. Thus it requires 315,000,000
acres to supply the needs of 127,000,000 peo-
ple-plus certain exporLs.
In this country we support forty people to
the square mile. In the better parts of the
[24]




STORY OF THE EARTH'S SOILS
Nile valley of Egypt a square mile supports
1,000 people; in Belgium 700; in England 685;
in Holland 660; in Germany 364.
Soil impoverishment is followed by human
decadence. The countries that led in power
and prestige in ancient times are least in mod-
ern times. Even in the United States stan-
dards of living are reflected in the statistics
of education advantages. According to a
report of the T.V.A. the percentage of one-
room schools and inexperienced teachers in
poor areas is seventy-six, and in rich soil
areas it is forty. It is also true that a larger
per cent of students of institutions of higher
learning come from the more productive
areas than from the low productive areas.
Our bodies should have some eighteen
different minerals in their composition, in
varying proportions, and these must be had
from food-which in turn must get them from
the soil. When the soil is deficient our bodies
must be deficient and to that extent less resis-
tant to the inroads of all manner of diseases.
Scientific agriculture and the invention and
use of farm machinery have warded off the
encroachment of limited food supply which
[25]




SCIENCE IN AGRICULTURE
otherwise would have overtaken millions of
inhabitants throughout the world. The trans-
portation facilities of today render it possible
to ship food from one part of the world to an-
other and ward off the wholesale starvation of
those visited by drouths and floods. Mastery
of the soil and the enemies of crops is the great
task of future generations.


[26]







SOIL WASTE
MAN is both constructive and destructive.
The one is commendable and the other
reprehensible. The one yields rewards and
the other brings punishment.
Of all the countries inhabited by man none
were endowed by nature with greater re-
sources tha i the United States of America.
Yet in no country at any time has there ever
been so much destruction carried on by man
in so short a time as in this country.
In no country has man conserved the soil
as it should have been. We see the devas-
tating effect of soil erosion wherever erosion
was possible. In Babylonia, Assyria, Pales-
tine, Greece, Italy and other parts of the an-
cient world. The only reason Egypt is not in
the list is because the narrow valley of the
Nile is all that was cultivated and it was re-
plenished annually by overflows which built
up an alluvial soil in a plain too level to wash.
Nowhere has so much fertile soil been allowed
to wash away in so short a time as in the
United States. Half of our cultivated area
[27 ]




SCIENCE IN AGRICULTURE


Wind Erosion


has been either totally ruined or depleted by
erosion. In some instances this was unavoid-
able but not often.
Three-fourths of our wonderful forests have
been ruthlessly destroyed. Billions of feet of
fine timber were piled and burned because
the owners wanted the land to cultivate and
the timber had no commercial value at the
time. Forest fires have destroyed billions of
feet of as fine timber as ever grew. Not all the
[28




SOIL WASTE
depletions were waste. Full value was re-
ceived for much of the forests and other stored
wealth. But comparatively little effort was
made to replenish the wealth swept from the
virgin lands.
Our mineral resources have been waste-
fully mined and allowed to waste. Coal has
been mined in such wasteful manner as to
lose a big per cent of it. Our oil supply has
been expensively handled and wastefully
exploited. Any mineral lands open to the
competitive exploitation of individuals and
corporations will be handled without thought
of conservation. Immediate profits are all
that is considered.
Production and consumption are not syn-
chronized to social needs. Irresponsible
ownership has led to most of the waste that
has been going on. This irresponsibility is
equally chargeable to individuals and to cor-
porations. No resource is inexhaustible. Not
to recognize this is folly and not to care is
criminal.
The national government has just recently
recognized this situation and inaugurated a
system of rehabilitation intended as an
[29]




SCIENCE IN AGRICULTURE
agency of conservation and reconstruction.
By encouraging conservation effectively and
discouraging destruction effectively much
can be accomplished.
The waste of physical resources is not to
compare with waste of human resources.
The average individual wastes more time
than it would take to accomplish all that he
does accomplish. Any waste of energy by
the individual, either in idleness or in pur-
poseless activity, from indifference or from
self-indulgence, is not only a detriment to one-
self but must necessarily be a detriment to
others. Instability and resentment toward
all discipline marks the career of multiplied
millions which, in the end, means dissipated
lives. The improvident are to be found in all
human affairs and each generation repeats
this record in the face of endless retribution.
We seem prone to refuse to profit by the les-
sons of the past.
Our profligate habits are illustrated by the
estimated waste of seven billions for gam-
bling; one billion for soda pop; one billion for
cigarettes; unestimated millions for hooch. In
1927 120,000 fans paid $2,600,000 to see Gene
[30]




SOIL WASTE
Tunney and Jack Dempsey pound each other.
No sport makes Jack a dull boy but squan-
dering on debaucheries and on things that
damage is no credit to any people. It is worse
than mere waste; it is degrading. An ex-
change of money from one gambler to an-
other does not necessarily mean an economic
loss so long as both live in the same country.








,t7'


[31]






AVERAGE DEPTH OF EROSION
TREATMENTInd=
TREATMENT .0 02 0.4 0. 0.8 1.0 1.2
CULTIVATED (Uncontrolled)
BARE (Uncontolled)
VOLUNTEER COVER
GRAIN I
NATIVE COVER (Gasor brush) I
TERRACES
BASIN LISTING
COVER CROP 1
037
Average depth of erosion under different types of treatment.


COVER CROP ...

BASIN LISTING f f

TERRACES ...... ,L lft ,

NATIVE COVER 9~ I f I
Grass or brush
GRAIN........... It9 efit f t

VOLUNTEER .... pBI I
COVER


BARE ...... i i l oe
Uncontrolli llli ed o Pf



CULTIVATED... . ii9 f f
Uncontrod ar a ag



SEach symbol presents S cubic yards o topsoil

Soil loss in cubic yards per acre for land under various types of treatment.
FEDERAL GOVERNMENT REPORT





VII
SOIL-BUILDING PLANTS
LEGUMES
T HE word legume as defined in unabridg-
ed dictionaries is a "l-celled, 2-valved
generally dehiscent seed vessel or pod form-
ed of a simple pistil having the seeds arrang-
ed along an inner or ventral suture, as in
beans or peas. Indehiscent legumes break-
ing at maturity into 1-seeded joints are called
loments." A dehiscent seed-pod is one that
opens for the seed or pollen to escape.
Not every plant that answers to this defini-
tion is nitrogenous. Quite a number of nitro-
genous plants do not come under this defini-
tion of a legume. Other dictionaries than the
one above quoted include clovers among the
legumes but not because they are in any way
nitrogenous.
NITROGENOUS PLANTS
It is not because of the seed container or
pod that the legume is valuable as a soil-
builder but because of the nitrogenous qual-
[33]




SCIENCE IN AGRICULTURE


ity of their root systems. Storing nitrogen in
the soil by means of nodules on the roots
makes this group the best soil builders of all
crops. There is a bacteria that feeds on the
roots and cause warty growths on the roots
and by a strange process of nature these
nodules collect nitrogen from the air and
store it for future use in the growth of plants.
Nitrogen is a "tasteless, odorless, colorless
gaseous element found in the mineral king-
dom, as in the air-forming four-fifths of it in
volume-in the vegetable kingdom as a com-
mon constituent of plant tissues and in the
animal kingdom as in the various tissues of
the body." It is necessary for the production
of protoplasm. It builds the body, promotes
vigorous growth and gives rich green color
to plant leaves.
The regular commercial fertilizer contains
nitrogen, phosphate and potash, in varying
proportions. Recently it has been found that
these are not all the ingredients that a bal-
anced ration for plants should have. Some
soils do not have enough lime, some not
enough calcium, etc. Tests on this investiga-
tion have proved that the minor elements
[34]




SOIL-BUILDING PLANTS


Crotalaria
should be supplied if the best results are to
be obtained.
In common with all green crops nitrogen-
ous plants furnish soil-building materials in
the form of humus which retains moisture and
furnishes a habitat for bacteria; this bacteria
in turn decomposes the vegetable matter
and adds fertility to the soil; to this is added
nitrogen and this makes soil improvement
much more rapid than do crops that collect
no minerals from the air. No plant brings
[35]




SCIENCE IN AGRICULTURE
potash or phosphate from the air to complete
the combination required for the balanced
ration for plants.
Some plants are classed as soil-improving
which merely protect from erosion and may
be turned under as a green fertilizer. Small
grains such as wheat, oats, rye, etc., used as
cover crops are mainly soil-conserving rather
than soil-building.
Among the soil-depleting crops when al-
lowed to come to maturity may be mentioned
wheat, corn, cotton, tobacco, potatoes (white
and sweet), rice, sugarcane, millet, sorghum,
peanuts when harvested, soy beans when
harvested, and the many truck crops. These
crops must be grown as they constitute the
bulk of the absolutely necessary crops for
man and beast. Balancing these with those
that do not exhaust the soil is necessary for
good farming.


[361





VIII

CONSERVATION OF SOILS
CLASSIFICATION OF CROPS

CROPS are classified into three classes.
They are soil-depleting crops, soil-con-
serving crops, soil-building crops.
Soil-Depleting Crops:
1. Corn (including broom corn and sweet corn);
2. Cotton;
3. Tobacco;
4. Irish potatoes;
5. Sweet potatoes;
6. Rice;
7. Sugarcane;
8. Commercial truck and canning crops; including melons
and strawberries;
9. Peanuts, if harvested as nuts;
10. Grain sorghums, sweet sorghums and millets;
11. Small grains, harvested for grain or hay, (wheat, oats,
barley, rye, and grain mixtures);
12. Soybeans, if harvested for crushing.
Soil-Conserving Crops:
1. Annual winter legumes, including vetch, winter peas, bur
and crimson clover; biennial legumes, including alfalfa,
kudzu, and sericea, with or without such nurse crops as
rye, oats, wheat, barley, or grain mixtures, when such
nurse crops are pastured or clipped green; summer
legumes, including soybeans, except when produced for
seed for crushing, velvet beans, crotalaria, cowpeas, and
annual varieties of Lespedeza.
2. Peanuts, when pastured.
[37]





SCIENCE IN AGRICULTURE
3. Perennial grasses, including Dallis, redtop, orchard, Ber-
muda, carpet, or grass mixture, and Sudan grass, with or
without such nurse crops as rye, oats, wheat, barley, or
grain mixtures, when such nurse crops are pastured or
clipped green.
4. Winter cover crops, including rye, barley, oats, and
small grain mixtures, winter pastured or not, and turned
as green manure; or if harvested and followed by sum-
mer legumes.

Soil-Building Crops:
1. Annual winter legumes, including vetch, winter peas, bur
and crimson clover, turned under as a green manure
crop.
2. Biennial legumes, including sweet and alsike clover;
perennial legumes, including alfalfa, kudzu, sericea, and
annual varieties of Lespedeza.
3. Summer legumes, including soybeans, velvet beans, cro-
talaria, and cowpeas, if forage is left on the land.
4. Winter cover crops, including rye, barley, oats, and small
grain mixtures, turned as green manure and followed in
the summer by an approved soil-conserving crop.

Approved Practices: in soil-conserving and soil-building in-
clude:
(a). Properly terracing land needing terracing.
(b). Growing and leaving on the land either winter or summer
legumes grown as catch crops.
(c). Seeding of crop land to perennial grasses including Ber-
muda, Dallis, redtop, orchard, carpet or pasture mixtures.
Stated another way we have:
Crop Soil Depleting Soil Building Soil Conserving
Cotton Yes -
Corn -
Tobacco -


[38]




CONSERVATION OF SOILS


Crop Soil Depleting Soil Building Soil Conserving
Potatoes (Irish
and sweet) Yes
All Truck Crops
(inc. watermelons) "-
Rice "-


Sugarcane
Small Fruits and Berries
Sugar Beets
Vineyards
Cultivated Nut
Crops (Including
Tung Oil)
Wheat If harvested
Oats
Rye
Barley
Buckwheat
Grain Sorghum


Broom Corn
Sweet Sorghums
Peanuts

Soybeans





All Field Beans
and Peas


If hay and
beans
harvested


If hay and
beans
harvested


When not harvested


When plowed
under
When plowed
under



When plowed
under


Plowed under or
grazed


When grazed
off
When left bn
land or pas-
tured or when
only seed
harvested
When left on
land or pas-
tured or when
only seed
harvested


[39]





SCIENCE IN AGRICULTURE


Crop Soil
Annual Forage If h(
grass crops fc
Annual Legumes
(Winter)
Biennial Legumes
(Sweet, Red, Alsike)
Lespedeza
Perennial Legumes

Woodlots
Pastures
Perennial grasses


Depleting
harvested
or hay


When plowed
under
Yes


Yes
- Exceptions by
Regions


Cassava
[40]


Soil Building Soil Conserving
Yes







SOILS AND FERTILIZERS
GENERAL PRINCIPLES
PHYSICAL man is made up of some eight-
een of the ninety known elements com-
posing the material universe. Man's exist-
ence is dependent upon his ability to make
the soil yield him a sustenance.
Soils are made up of small particles of dif-
ferent kinds of minerals mixed with more or
less organic matter. All geologists tell us
that these small mineral particles were orig-
inally formed by the breaking down of rocks
through glacial erosion, weathering, and de-
composition. The mineral kingdom is the
basis of the vegetable and animal kingdoms.
Plants and animals are partly mineral-man
is no exception.
So far, science has been able to isolate
ninety distinct physical elements. At least
eighteen of these are essential to the growth
of plant life-carbon, hydrogen, oxygen,
magnesium, iron, sulphur, calcium, phos-
phorus, and potassium, are the more impor-
tant.
[41]




SCIENCE IN AGRICULTURE
The elements taken entirely from the soil
are, calcium, iron, magnesium, phosphorus,
potassium, and sulphur.
Nitrogen is taken chiefly from the soil, but
a group of plants known as legumes-such
as clover, peas, beans, vetches, cowpeas,
alfalfas, etc.-gather part of their nitrogen
from the atmosphere. They accomplish this
by means of microscopic organisms which
live in small nodules or tubercles found on
the roots.
Combinations of the three elements, car-
bon, hydrogen, and oxygen, constitute 95%
of all plants. They form the fats and carbo-
hydrates, including the oils and starch.
Plants obtain their supply of these from the
air and water. The carbon is derived from
the carbon dioxide gas of the air, and the
hydrogen and oxygen from water, which is
itself a combination of hydrogen and oxygen
absorbed through the roots.
So that only about five per cent of the ma-
terial of plants actually comes from the soil.
Only minute amounts of magnesium, iron,
and sulphur are required and they are pres-
ent in most soils in abundant quantities. The
[42]




SOILS AND FERTILIZERS
same is usually true of calcium, although
certain crops, particularly clover, require this
element in considerable amounts. So, by
process of elimination, we find that seven of
the eighteen elements essential to plant
growth, need give the farmer but little con-
cern.
The efficiency of soil is measured by its
capacity to supply plants with the several
materials and conditions they require for
growth; these include physical support, wa-
ter, heat, air and food. These elements of
healthy plant environment must exist in well-
balanced proportion and abundance to in-
sure bountiful yields-even from the best of
cultivation and the absence of disease and
insect or animal enemies. The vast variety
of climates, soils, and soil conditions deter-
mine the kind and location of the many vari-
eties of plants.
Generally speaking, the water, heat, and
air are furnished by nature. It also furnishes
the food in great measure, but of recent years
a great deal of artificial feeding of plants has
been practiced by farmers. This gives rise
to the manufacture and use of fertilizers.
[43]




SCIENCE IN AGRICULTURE
Nitrogen, phosphorus, and potassium are
three elements which in their various combi-
nations, constitute the vast majority of the
material obtained from the soil by plants.
These elements do not exist in the soil as
single elements, but are found combined with
other elements, and plants can only appro-
priate their foods when they exist in certain
combinations, and under certain physical
conditions.
The following mineral elements are also
needed by plants in different degrees and
proportions: Iron, manganese, chlorine, sul-
phur, silica, carbon, iodine, bromine, boron
and lithium.
No chemical analysis of either the soil or
the plant will show dependably and accu-
rately just the combination of ingredients
which should be used. Soil analysis shows
the chemical content, but does not show con-
clusively the availability of plant foods. The
mechanical condition, which cannot be as-
certained by chemistry, goes farther in de-
termining the fertilizer needed, than the ac-
tual plant food taken up by the growing
plant. It is also true that a crop test is the
[44]




SOILS AND FERTILIZERS


only absolutely reliable means of determin-
ing the availability of plant food in fertilizers,
as that availability is largely determined by
the physical or mechanical condition of the
soil.
The Federal Bureau of Soil Surveys, of
Washington, D. C., has found over 6,600 com-
binations of soils in the United States. There
is but little information to be derived from a
soil analysis that would be of benefit to farm-
ers. So much depends on drainage and
various physical conditions that an analysis
made under laboratory requirements is of
little value.
A chemical analysis may indicate a very
fertile soil, rich in plant food, while the facts
are the soils are not productive. This is in-
stanced by the rich muck lands and river
bottoms, that are fertile chemically, but not
productive until properly drained and sweet-
ened by the use of lime; also, by the arid lands
of the west, rich in the elements of plant food,
but not productive until irrigated. Other soils,
with less plant food, but on account of proper
physical conditions are exceedingly produc-
tive.
[45]




SCIENCE IN AGRICULTURE
The discovery that the kind and amount of
fertilizer which should be used on a certain
soil to insure the best result from a certain
crop can be ascertained only by actual test
in growing it, was a sore disappointment to
agronomists and is disconcerting to the far-
mer.
There are several methods used in deter-
mining the availability of plant foods in fer-
tilizers; the neutral permanganate method,
and the pepsin hydrochloric acid method are
used to determine the availability of plant
foods, and they differ so widely that 65% as
shown by the latter is equal to 85% as shown
by the former. The Kjhldahl method is also
used to ascertain the nitrogen content of in-
gredients making up a compound fertilizer,
but the availability for plant food of the ele-
ments contained is not so easily registered.
All the power of growth possessed by plant
life is dependent upon the presence and
availability of the plant foods with which the
rootlets come in contact.
One food cannot take the place of another.
No amount of preparation, seed selection, or
cultivation will produce a crop when the
[46]




SOILS AND FERTILIZERS
proper plant foods are not in the soil. If two
are there in superabundance, and the third
totally absent, the labor is lost. We fertilize
when we apply either ammonia, phosphoric
acid, or potash in an available form. A com-
plete fertilizer must contain all three, but not
necessarily in equal parts. The food that is
present in least amounts limits the crop.
Plants need a "balanced ration" the same as
animals.
Plant food is drawn in through the tiny,
hair-like fibrous rootlets. Each of these fib-
rous feeders is covered with a thin skin. All
the food plants get must pass through this
skin. The process is very much like that of
body-building from digested food in the stom-
ach and alimentary canal of animals-in-
cluding human beings. The villi of the diges-
tive tract are analogous to the root fibers that
take up the soil water which holds in solution
the dissolved plant food elements. The fuzz
on the roots has no perceptible openings
through which the finest powdered dust could
get. Plant food which will dissolve so as to
go with the water through the skin of these
tiny roots is called soluble and is therefore
[47]





SCIENCE IN AGRICULTURE
available for plant nourishment. The plant
food thus drawn in by the fibrous rootlets
passes up through the roots, the trunk, stalk
or stem, then the branches and out into the
leaves or blades where most of the water is
evaporated, transpired, or breathed off into
the air. A process of exchange, of transpir-
ing, and absorption takes place in foliage-
much like the process which takes place in
the lungs of animals that breathe out car-
bonic acid gas and take in oxygen. The sap
of plants is elaborated in the foliac by this
exchange of moisture drawn up from the
ground, and the taking in of gasses from the
air. After this "elaboration," the sap flows
back to build up the plant and its fruit-just
as blood flows back from the lungs, where it
is surcharged with oxygen, to the heart and
thence through the arteries to the capillaries
in all parts of the body where assimilation or
body-building takes place.
Plants exposed to light develop chlorophyl,
which is the coloring matter that gives the
shades to certain portions of the protoplasm.
The function of chlorophyl consists of the ab-
sorption of carbon-dioxide gas, resulting in
[48]




SOILS AND FERTILIZERS
the transformation of oxygen and the forma-
tion of new organic substance.
A plant food is much more available when
locked up in some medium than in others.
Certain sources of nitrogen yield it up to the
action of soil moisture more readily than
others. This makes the source of nitrogen,
phosphorus, or potash of importance to the
farmer, who may want either rapid or grad-
ual solubility to suit a quick, or slow-growing
crop.
Justice Von Liebig was the founder of Agri-
cultural Chemistry. It was he who discovered
that plants feed on soil chemicals, and if these
are not in the soils in form available for the
growing plant to appropriate there can be no
growth and no yield of harvest. He demon-
strated how crops depleted the soil, and how
worn out soils could be restored to fertility by
the application of artificial fertilizers.
He announced his discovery in 1840.
Next to the knowledge of plant breeding
the knowledge of plant feeding has had the
most important bearing on modern agricul-
ture. When we think of the magnitude of the
commercial fertilizer business throughout the
[49]




SCIENCE IN AGRICULTURE


world it is indeed remarkable that the knowl-
edge of the chemistry of the soils came to our
service at so recent a date. If the ancients
had possessed this knowledge history might
have been different.
No iron-clad formula for commercial ferti-
lizer can be made to suit all soils. The avail-
able plant food in the soil and the amounts
of each of the ingredients of a mixed fertilizer
that a given crop draws from the soil per acre
is the basis for determining the formula for the
crop.
The availability of plant food in soil, the
chemists tell us, cannot be determined in the
chemical laboratory. Some chemists tell us
that it is impossible to ascertain accurately
the availability of plant foods in commercial
fertilizer or in soils.
There are three forms of nitrogen in soils,
and should be in well-balanced fertilizers-
organic, ammoniacal and nitric. The last
named is soluble and immediately available
for plants. Ammoniacal nitrogen is convert-
ed into nitric form by the action of bacteria
and soil chemicals in rather a short period.
Organic nitrogen takes somewhat longer,
[50]




SOILS AND FERTILIZERS
due to its process of being changed to the
ammoniacal form before the plants take it up.
Plants get their carbon from the air by way of
their foliage and this combines with the oxy-
gen in the water taken up by the roots to form
carbonic acid, which in turn, dissolves com-
pounds supplied by the soil solution. The
hydrogen in the water combines with nitro-
gen to form ammonia, and this combination
depends very largely on the warmth and
depth and texture of the soil as well as on the
action of favorable bacteria. The amount of
moisture in the soil goes a great way toward
determining the action of bacteria. The tilth
-depth of tillage or amount of soil available
for plant roots-of soil is as much a determin-
ing factor as the mere presence of plant food
elements. Oftentime the farmer will use barn-
yard manure in connection with commercial
fertilizer, in which case it is an indeterminate
equasion as to what is the best formula to be
used. The kind, quantity and quality of the
manure would have to be known before the
formula and quantity of commercial fertilizer
needed could be determined.


[ 51]




SCIENCE IN AGRICULTURE
HIGHER ANALYSIS FERTILIZERS
Generally speaking, the getting away from
lower analysis fertilizers to the higher analy-
sis ones is quite a saving to the farmer. Some
states have enacted laws fixing a minimum
standard for total available plant food in
mixed fertilizers. The value of a ton of fertilizer
lies wholly in the number of units of plant food
it contains together with the small amount of
the rarer elements which it may also carry,
that are necessary to plant growth.
The higher the analysis of the fertilizer, the
more economical it is to the farmer. For in-
stance, a fertilizer containing 20 per cent total
available plant food can be had, which is
made from materials equally as good as one
containing 14% total available plant food.
There are six more units of plant food for the
same freight; a very small amount more profit
to dealer, and the same labor of handling. A
twenty-eight per cent goods has an even
greater saving. However, higher analysis
goods naturally contain less of the rarer ele-
ments necessary to plant growth.
There are now appearing synthetic fertiliz-
ers on the market in large quantities. These
[52]




SOILS AND FERTILIZERS
will run from twenty-five to sixty and even
sixty-five per cent total available plant food.
They are concentrated chemicals and carry
nitrogen, available phosphoric acid and pot-
ash. They do not carry much of the other
mineral elements; such as iron, manganese,
iodine, bromine, boron, lithium, copper and
magnesium; needed in small amounts for
most plant life. Cover crop and organic fer-
tilizer will go far toward rectifying this defi-
ciency.

SOME IMPORTANT DATES IN FERTILIZER HISTORY

1824-Two barrels of Peruvian Guano arrived in Baltimore.
1825-Ground bone first used as fertilizer in the United States.
1830-First nitrate exported from Chile to Norfolk, Virginia.
1832-First commercial importation of Peruvian Guano.
1832-"Calcareous Manures" by Edmund Ruffin, published at
Petersburg, Virginia.
1840-Von Liebig proposes "mineral theory" of plant feeding-
treats bones with sulphuric acid.
1840-Sir John Lawes begins experiments at Rothamsted, Eng-
land.
1840-By-product ammonia salts first produced in England.
1845-Value of potash first demonstrated by Von Liebig in
Germany.
1850-First mixed fertilizers (manufactured guanos) produced
in Baltimore.
1867-Value of South Carolina phosphates first recognized.
1869-70-Potash first imported into the United States.
[53]





SCIENCE IN AGRICULTURE
1872-First fertilizer experiment in the United States begun at
State College, Pennsylvania.
1881-Florida phosphate deposits discovered.
1889-Western phosphate deposits discovered in Utah. (Enor-
mous deposits discovered later in Montana and Idaho.)
1893-By-product ammonium sulphate first produced in United
States.
1893-94-Tennessee phosphate deposits discovered.
1907-Concentrated superphosphate produced at Charleston,
South Carolina.
1910-Cyanamid production begun at Niagara Falls, Canada.
1915-First American potash produced commercially at Searles
Lake, California.
1922-First commercial production of synthetic nitrogen in the
United States.
1929-First shipment of synthetic nitrate of soda from Hopewell,
Virginia.
1931-First commercial shipment of potash from Carlsbad, New
Mexico.


[54 ]





X
AIR AND LIFE

THERE is nothing more important to life
than air. It is a colorless, odorless, taste-
less, gaseous mineral. Yes, we breathe min-
erals, drink minerals and eat minerals. Our
corporal bodies are made up of minerals, or-
ganized and vitalized by life forces only par-
tially understood. The atmosphere is made
up of nitrogen and oxygen, with traces of five
other gases-argon, neon, krypton, xenon
and helium. The following impurities are
often also found, ammonia, sulphuric acid,
and carbon dioxide.
Oxygen supports life and combustion.
Breath brings oxygen in contact with blood in
the lung cells and absorbs carbon dioxide
and gives it off in the exhalations. Genesis
says that God "breathed into man's nostrils
the breath of life and he became a living
soul."
We live, move and have our being in this
belt of atmosphere surrounding the earth.
The weight of air at sea level is calculated to
be 15 pounds to the square inch. Were it of
the same density all the way up it would be
[55]




SCIENCE IN AGRICULTURE
only about five miles deep. But its density
decreases at a high ratio as the distance from
the earth increases. No one knows positively
just how far from the earth's surface the air
extends. It is usually considered as about
fifty miles, but unmanned balloons, carrying
recording instruments, have gone as high as
20 miles. From records thus obtained Sir
James Jeans estimates that the air extends in
a very rarefied state to at least 1,500 miles.
Doubtless this outer rim of air is void of some
constituents which it has at the earth's sur-
face. Air is compressible but water is not.
It is also believed that without air all would
be darkness. Astronomers are of opinion
that the moon is airless. The sun's rays strik-
ing it are reflected to the earth and renders
light to the earth.
What is beyond the air? A number of
theories have been advanced. The one most
generally accepted is that all space is filled
with "the ether," (not the drug ether). Dr. Al-
bert Einstein takes the position that there is
no such thing as "the ether." He cannot be
ignored as a scientist. If anything occupies
the boundless expansions of space between
the bodies revolving and racing through
[56]




AIR AND LIFE
space it must be of a nature that offers no
resistance to moving bodies or they would
gradually be slowed down by its presence.
Yet it is inconceivable that any substance
can exist that would offer no resistance.
The rays of the sun are of different vibra-
tions. The simple prism separates the rays
producing colors as they pass through it.
There are other rays that do not produce col-
ors. The X-ray penetrates objects that are
opaque to the color rays. It can be produced
by electricity under proper contrivance. Next
comes the Gamma rays and then the cosmic
rays reach the ultimate of frequency of elec-
tro-magnetic waves measured in kilocycles
per second.
The effect of these rays as they strike the
earth is largely controlled by the atmosphere.
But for the modifying influence of the air some
of these rays would be deadly in effect on all
life. This balance between the direct rays
and the depths, density and composition of
the air renders it possible for the planet to be
inhabited.
Any organism which grows in the absence
of free oxygen is an anaerobee". This proc-
ess of growth is therefore called "anaerobia-
[57]




SCIENCE IN AGRICULTURE
sis". Free oxygen is oxygen which is not in
chemical combination with some other ele-
ment or group of elements. For instance,
water is composed of hydrogen and oxygen,
but water possesses the characteristics of
neither hydrogen nor oxygen. Hydrogen
and oxygen are both gasses, while water is
a liquid, etc. In other words a chemical com-
bination has taken place, the result of which
does not exhibit the properties of the original
elements. In this case oxygen is bound to
hydrogen and is not free. The only way in
which we can regain this oxygen is to reverse
the chemical reaction which changed the two
into water.
On the other hand, water may have all
kinds of gasses dissolved in it, but not in
chemical combination with anything. These
gasses are free. In other words, they can be
recovered by merely absorptive processes (or
in other ways) without involving a chemical
reaction. Oxygen dissolved in water is still
oxygen, but the oxygen which goes to help
make up water is not oxygen.
Oxygen in the air is free. In fact, all oxygen
is free if it is not chemically combined with
something.
[58]






PLANT AND ANIMAL LIFE
LIFE KINGDOMS

T HE two great life kingdoms are the vege-
table and the animal. There is a point
where the two kingdoms so nearly blend that
the line of demarcation eludes the scientist.
Zoology being that branch of biology that
treats of animal life, has various schemes of
classification adopted by naturalists. The fol-
lowing classification is standard and will
help us to locate our subject in the general
scheme of biological studies. (Many smaller
divisions are omitted.)

CLASSIFICATION OF THE ANIMAL KINGDOM

Phylum I; Protozoa (One celled animals)
Class 1, Sarcodina
Class 2, Mastigophora
Class 3, Sporozoa
Class 4, Infusoria
Phylum II; Porifera (Sponges)
Phylum III; Coelenterata (Forms possessing a coelenteron)
Phylum IV; Ctenophora ("See Walnuts")
Phylum V; Platyhelminthes (Flatworms)
Phylum VI; Nemathelminthes (Roundworms)
Phylum VII; Annelida (Segmented worms)
[59 ]





SCIENCE IN AGRICULTURE
Phylum VIII; Arthropoda (Joint-footed animals; lobsters, crabs,
centipedes, scorpions, spiders, mites, insects)
Phylum IX; Mollusca (Snails, clams, oysters, octopods, nautili)
Phylum X; Echinodermata (Starfish, sea urchins, sea lilies,
etc.)
Phylum XI; Chordata
Sub-phylum 1; Enteropneusta
Sub-phylum 2; Tunicata
Sub-phylum 3; Cephalochorda
Sub-phylum 4; Vertebrata
Class 1 Cyclostomata (Lampreys and Hags)
Class 2 Elasmobranchii (Sharks, Rays, etc.)
Class 3 Pisces (Fish)
Class 4 Amphibia (Frogs, Toads, Salamanders)
Class 5 Reptilia (Turtles, Lizzards, Snakes, Crocodiles)
Class 6 Aves (Birds)
Class 7 Mammalia (Hairy Quadrupeds, Whales, Seals,
Bats, Monkeys, and Man)

*DIVISIONS OF THE ANIMAL KINGDOM

Some specialized fields of biological study are as follows:
1. Mammalology treats of mammals, a class of vertebrates
whose females have milk-secreting mammary glands to
nourish their young, embracing all warm-bodied quadru-
peds,-also bats, seals, cetaceans and sirenians;
2. Ornithology, of birds;
3. Herpetology, of reptiles;
4. Ichthyology, of fishes and lower aquatic vertebrates;

*Those organisms that destroy, and subjects relating thereto, are capitalized in
the following outline. We are concerned about those that are useful but for the
present discussion we are more concerned about the destructive creatures of the living
world.
There are disorders of plants and animals caused by numerous things other than
parasites. Among the diseases of plants which are not caused by organisms may be
mentioned those caused by injurious sprays, poisonous gases, malnutrition, dieback due
to lack of drainage or too much ammonia, etc. Injuries from frost, heat, flood, drought,
depredations by insects and higher animals are not really diseases.
[60]





PLANT AND ANIMAL LIFE

5. Ascidiology, of the tunicata-a division of metazoans;
6. Echinology, of the echinodermata-a division variously
ranked;
7. Conchology, of the molusca;
8. ENTOMOLOGY, of the INSECTA;
9. ARACHNOLOGY, of the ARACHNIDA-spiders, scorpions,
etc.;
10. Crustaceology, of the crustacea-lobsters, crawfish, shrimp,
prawns, barnacles, sow bugs, etc.;
11. HELMINTHOLOGY, of the worms;
12. Zoophytology, of the coelentera-invertebrates as coral,
or hydroid, the sea anemones, jelly fish, etc.;
13. Paleontology, of the fossil remains of plants and animals;
14. Parasitology, of parasitism.

DIVISIONS OF THE VEGETABLE KINGDOM
Botany being the science of plants is somewhat older than
zoology, but its nomenclature was long the subject of con-
troversy. The International Botanical Congress of 1905 (which
met in Vienna) adopted certain rules which have done much
to bring order out of confusion. The branches of botany of
most concern here are:
1. Morphology, relating to external form;
2. Histology, relating to structure of tissues;
3. Cytology, relating to the cell;
4. Embryology, deals with the development of the egg-cell;
5. Physiology, with the functions and vital actions of organs;
6. PHYTOPATHOLOGY, with PLANT DISEASES;
7. Ecology, with environment influences;
8. Phytogeography, with plant distribution;
9. Taxonomy, with the classification of plants;
10. Paleobotany, of fossil plants;


[61]





SCIENCE IN AGRICULTURE


11. ECONOMIC BOTANY,-including:
(a) Agriculture
(b) Forestry
(c) Horticulture
(d) Pharmacognosy
(e) Floriculture
and cognate subjects.

Animal life is defined as "Sentient organisms, having or-
gans of sense; life which feed on other organisms. Animal life
is usually to be distinguished by its ability to take food into a
digestive tract or cavity, and by the power of voluntary motion."
The comparative relationship of the various divisions may
be shown as follows:
1' Kingdom
21 Phylum
31 Sub-Phylum
4' Class
51 Sub-Class
61 Order
71 Sub-Order
81 Family
9' Sub-Family
101 Genus
11' Species
121 Breed
22 Phyla: 131 Strain
31 Protozoa
32 Porifera
33 Coelenterata
34 Vermes
35 Mollusca
36 Echinodermata
37 Vertebrata
38 Arthropoda
[62]





PLANT AND ANIMAL LIFE


Vegetable life is defined as "living organisms not possessed
of animal life."
The comparative relationship of the various divisions may
be shown as follows:
1 Kingdom
2' Phylum
31 Sub-Phylum
41 Class
51 Sub-Class
6' Order
71 Sub-Order
8' Family
91 Sub-Family
101 Genus
11' Species
121 Breed
131 Strain


22 Phyla:
31 Cryptogamia: flowerless-propagating by
spores
41 Myzophyta: slime moulds
42 Thallophyta: algae, fungi and lichens
43 Bryophyta: mosses and liveworts
44 Pterodophyta: ferns and their allies
45 Schezophyta: fusion plants, including bacteria
4' Phanerogamia: flowering-having stamens and
pistils
51 Angiosperms
61 Dicotyledons
62 Monoctyledons
52 Spermatophyta
53 Gymnosperms


[63]





SCIENCE IN AGRICULTURE
DIVISIONS ON ANOTHER BASIS
On another basis we may divide animal life as follows:
A. Vivipora: Those which are born and suckle their young
a Man
b All warm-blooded quadrupeds
c Bats, seals, cetaceans and sirenians
B. Ovipora: Those that hatch from eggs and do not suckle
a Fish
b Fowls
c Insects
d Reptiles-exceptions
C. Spores: Containing no embryo
a Protozoans
b Bacteria

CLASSES OF PARASITES
The Diseases They Produce, and Remedies
Al Animal Parasites: Any form of animal life that lives in or
on and at the expense of another form.
a2 Insects: Six-legged arthropods; 300,000 species have
been named and five times as many unnamed.
a3 Kinds
a4 Chewing
a5 Curculio
b5 Codling moth
c5 Canker worm
d5 Fall web worm
e5 Tent caterpillar
f5 Pear slug
g5 Larva of moths and butterflies
h5 Beetles and their grubs
i5 Grasshoppers
j5 Crickets
k5 Saw flies and their larva

[64]





PLANT AND ANIMAL LIFE
Sprays for Chewing Insects
1. Paris green
2. Arsenate of lead
3. Arsenate of soda
4. Arsenate of lime
5. Scheele's green
6. London purple
7. White arsenate
8. Hellebore
b4 Sucking
a5 San Jose scale
bS Oyster shell scale
c5 Plant lice
d5 Leaf hoppers
e5 Pear psylla
Sprays for Sucking Insects
1. Lime sulphur concentrates
2. Self-boiled lime-sulphur mixture
3. Fish-oil soap wash
4. Kerosene emulsion
5. Crude petroleum emulsion, distilled
emulsion
6. Nicotine solution
7. Pyrethrum
8. Caustic potash
9. Carbolic acid emulsion
10. Sulphur spray
11. Resin wash
Fumigants
Effective against all insects when feasible to use them:
1. Hydrocyanic-acid gas
2. Carbon disulphide
3. Sulphur dioxide
[65]





SCIENCE IN AGRICULTURE
The female mosquito is carnivorous, while the male is her-
bivorous. That is to say, collectively, it eats herbs and sucks
blood, therefore is both a chewing and a sucking insect-
chewing plants and sucking animals. It is a menace only to
the latter.
B1 Vegetable Parasites: Organisms not possessed of animal
life; 400,000 species have been described.
a2 Fungi: Thallophytic plants destitute of chlorophyl
a3 Obligatory parasites, with power to exist under but
one condition
b3 Faculative parasites, having power to accommo-
date themselves to different conditions
c3 Obligate saphrophytes, living on dead organic
matter
d3 Faculative saphrophytes, living without free oxygen.
Diseases They Produce In Plants


Citrus canker
vispora.


1. Brown rot of peach
2. Bitter rot of apple
3. Rusts
4. Scabs
5. Moulds
6. Smut
7. Mildew
8. Some "blights"
9. Citrus canker
is caused by the fungous Macrophoma cur-


Sprays for Vegetable Parasites
1. Bordeaux mixture
2. Lime sulphur
3. Sulphur dust
4. Copper sulphate-lime dust
5. Corrosive sublimate
[66]





PLANT AND ANIMAL LIFE


b2 Slime Moulds: Not differentiated into cells, a mass of pro-
toplasm propagating by spores-functioning as seed in
plants.
c2 Cuscuta
d2 Bacteria: The unicellular variety which propagates by
fisson-splitting of the organism. No universally accepted
and satisfactory classification of bacteria has been made.

Methods of Transmission of Plant Diseases

There are a number of methods by which plant diseases are
transmitted:
1. By soil inoculation: such as the Irish potato scab, the Irish
potato rhizoctonia, and the same with beans and onions, to-
mato fuscopiceous wilt, and lettuce drop.
2. By water infection: as the lemon brown rot of California.
3. By air infection: as the lemon scab, celery leaf spot,
cucumber downy mildew, tobacco peronoaper, peach brown
rot.
4. By insect transportation: such as pear fire blight, cucum-
ber wilt-bacterial-potato mosaic, peach brown rot.
5. By seed inoculation: as bean anthracnose, bean bacterial
blight, sugarcane red rot, watermelon anthracnose, cucumber
angular leaf spot.
6. By dead wood: such as wither tip of citrus fruit, stem-end
rot of citrus fruits.
7. By miscellaneous methods: some diseases are spread by
more than one method.

Other Divisions of the Subject of Plant Diseases

As to effect of disease on plants:
1. Killing: blights, rusts, wilts, etc.
2. Reducing health conditions
3. Producing malformations
[67]





SCIENCE IN AGRICULTURE
As to parts affected:
1. Roots
2. Stalk
3. Foliage
4. Fruit
As to kind of plants attacked:
1. Forests
2. Fruit groves
3. Field crops
4. Truck crops
5. Ornamental shrubs
6. Vines
Pathology is the study of abnormal conditions; their causes,
symptoms and characteristics-including a study of physiology
and anatomy.
Therapeutics is that department of medical science that
relates to the treatment of disease and the action of remedial
agents on the organism, both in health and disease.
A physician is one versed in or practicing the art of medi-
cine or healing bodily diseases, usually by the administration
of remedies regarded as standard by the profession-such as
are in the Pharmacopoeia.

Forms of Bacteria
A bacterium is a schizomycetes, or microscopic fusion fungus
-a non-spore former.
Spherical bacteria-cocci.
Rod-shaped bacteria-bacilli-spore former.
Spiral bacteria-spirilla.
Pathogenic bacteria: capable of doing harm directly-a few
score of them. Two general classes: those which are strictly
parasitic and those which live free in nature. A full list of
the species and of the diseases which they produce would
be too comprehensive for present purposes even were such a
list scientifically established.

[68]





PLANT AND ANIMAL LIFE


NAME OF ORGANISM
Corynebacterium diphtheria
Microbacterium leprae
Clostridium tetnai
Clostridium botulinum
Salmonella enteritidis
Ebrethella typhi
Ebrethella para-typhi A
Ebrethella para-typhi B
Brucella abortus
Irucella melatensis
Neisseria gonorrhoeae
Treponema pallidium
Pneumococcus (types 1. 2. 3. 4)
Staphylococci (several types)
Streptococcus scarletina
Shigella dysenteriae
Endamoeba histolytica
Vibrio comma
Lactobacillus acidophilus
Lactobacillus bulgaricus
Bacteria nitrifyingg)


TYPE OF DISEASE PRODUCED
Diphtheria
Leprosy
Lockjaw
Food poisoning (toxic)
Food poisoning (cellular)
Typhoid fever
Contagious abortion in cattle
Relapsing fever
Gonorrhoea
Syphilis
Pneumonia
Colds and sore throats
Scarlet fever
Dysentery iBacillary)
Dysentery (amoeboid)
Asiatic cholera
Sours milk
Sours milk
Lodge in root nodules where they fixate
nitrogen.


Such diseases as smallpox, measles, mumps, yellow fever, infantile paralysis (acute
anterior poliomyelitis), "parrot fever", and many others are caused by specific sub-
stances called filterable viruses, the nature of which has not been agreed upon by
authorities.

A plant pathologist is one versed in diagnosing and treating
plant diseases.
It is an anomaly in the economy of nature that human life is
dependent upon micro-organisms and at the same time the
greatest enemies of the human race are to be found among
these micro-organisms.
Some of the uses of bacteria may be mentioned-
In the Arts:
1. Maceration Industries-Such as Linen, lute, Hemp,
Sponges, Leather.
2. Fermentative Industries-Such as Vinegar, Lactic acid,
Butyric acid, Bacteria in Tobacco Curing.
In Natural Processes:
1. As Scavengers.
2. In Food Processes.
3. In Soil Fertility.
4. In Silo.
5. In the Dairy.

[69]




SCIENCE IN AGRICULTURE
The Science of microscopic life is modern in origin-in a
practical sense it is less than a hundred years old. All para-
sites are not microscopic, and such as are not received earlier
attention. Insects, fungi, and bacteria constitute a militant
army that is the most formidable enemy of the human race.
Some of these are man's friends, and it behooves him to
understand each class, that he may cope with the problems
which they present.
That branch of biology which includes a study of human
life reaches its highest and most complex themes in psychology
and sociology.
Morphology treats of form-the static form of life.
Physiology treats of function-the dynamic phase of life.
For the purpose of our present study we shall have to
confine ourselves to those branches of biology which have to
do with organisms that work an economic injury to the human
race, touching incidentally those which work a physical injury
in our treatment of bacteria.
Therefore, by process of elimination, we come to three
branches of biological study:
Entomology-the study of insect life, as it relates to plant
pathology and economic botany.
Mycology-the study of fungi, as it relates to plant pathology
and economic botany.
Bacteriology-the study of bacteria, as it relates to plant
pathology, economic botany and human pathology-patho-
genic bacteria.
The limitation of this volume will not permit a treatise on
each of these subjects. Therefore we shall devote space only
to pathogenic bacteria. The reader is concerned principally
with means and methods of destroying injurious insects, bac-
teria and fungi.


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PLANT AND ANIMAL LIFE
PATHOGENIC BACTERIA

Destructive Organisms

(Affecting the Human Body)

Pathogenic, disease-producing bacteria constitute a rela-
tively small number of species of bacteria. The harmless
species are not parasitic and cannot grow in an animal organ-
ism. There are two general classes of bacteria which cause
disease:
1. The non-pathogenic class, which live free in nature and
are not strictly speaking parasitic.
2. The true parasitic class, which live in the bodies of ani-
mals.
The most generally accepted theory of how bacteria cause
disease is that they produce in their growth a number of by-
products of decomposition and that some of these by-products
are poisonous. It has not been shown that all pathogenic
germs produce their effect that way, but it has been proven
that it is the method in a number of cases.
Other methods are tissue destruction and mechanical block-
ing of organs.
Recognizing that bacteria may produce poisons, we readily
see that it is not always necessary that they should be parasitic
in order to produce trouble.
Ptomaine poison is caused by eating putrified animal mat-
ter, or of alkaloids produced by bacteria. An alkaloid is any
nitrogenous organic base, especially of vegetable origin, hav-
ing a powerful toxic effect on the animal economy-as strych-
nine or morphine.
It is not always the case that a specific germ produces a
definite disease, nor that each germ disease has its specific
bacterium. For instance, the inflammation of wounds, for-
mation of pus, or the different types of blood poisoning, such
as septicaemia pyaemia, gangrene, etc., all appear to be
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SCIENCE IN AGRICULTURE
caused by bacteria, and it is impossible to make out any
definite species associated with the different types of these
troubles. The organism which normally causes influenza may
also cause such diseases as conjunctivitis, mastoiditis, osteo-
myelitis, meningitis, pneumonia, endocarditis, peritonitis,
bronchitis. There are three forms of so-called pus cocci, and
these are found almost indiscriminately with various types of
inflammatory troubles.
Organisms are in the air, in the ground, in the water, on
clothing, on the skin, in the mouth and the alimentary canal.
Commonly they do no harm, but they have the power of doing
injury if they get into wounds or susceptible membranes.
Some species are universal inhabitants of the alimentary canal
and are ordinarily harmless or beneficial but under other con-
ditions they invade the tissues and give serious trouble.
The following diseases are among those regarded as caused
by distinct specific bacteria: Typhoid fever, whooping cough,
scarlet fever, pneumonia, syphilis.
Most pathogenic bacteria can be in some way so treated
as to suffer a diminution or complete loss of their powers of
producing a fatal disease, on the other hand conditions may
cause an increase in the virulence of a pathogenic germ.
The general course of a germ disease is divided into three
stages: (a) incubation, (b) development, (c) recovery. Dis-
ease germs enter the body through the mouth, nose, skin and
secretary ducts.
The germs of scarlet fever, tuberculosis, pneumonia, etc.,
are carried to us through the air and breathed into the cells
of the lungs, where they find lodgment and penetrate the
delicate membranes and get into the circulation. It is then
that a battle ensues between the powers of the body and the
microscopic invaders. Only a few of the thousands of species
are able to combat nature's resisting power. Those that some-
times win out and produce disease we designate as pathogenic.
The human body possesses extremely remarkable protective
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PLANT AND ANIMAL LIFE
methods against the invasion of bacteria or other foreign sub-
stances. These defense mechanisms may be placed in three
general categories, namely: (1) Humoral antibodies-(agglu-
tinins, precipitins, lysins, opsonins and antitoxins). (2) Phago-
cytosis-(a function of the white blood cells). (3) Complement
or alexins. The last of these three may be placed with the
first as a humoral antibody, but differs from other humoral
antibodies in that it is non-specific for all types of invasion
into the blood stream, and in that it is always present in all
normal blood.
The introduction into the blood stream of any foreign sub-
stance will encite the activity of one or more of the above
protective agencies, and thus is the struggle to overcome dis-
ease begun. Recovery of the individual follows if enough
antibodies can be produced to successfully combat the invad-
ing organism. On the other hand, death follows if the invading
organisms are able to overcome the above mentioned pro-
tective agencies.
Once they have been formed, some antibodies persist
throughout the life of the individual. This is referred to as
lasting or permanent immunity. On the other hand, some
antibodies disappear from the blood stream as soon as re-
covery from disease is brought about. Diseases, consequently,
which produce antibodies that are easily disassociatable may
be had any number of times, and life immunity will never re-
sult. Influenza may be cited as a disease of this sort, since an
individual may contract it any number of times. Diphtheria
may, on the other hand, be cited as an example of a disease
which produces life immunity in all who recover from it, since
no individual may have it more than once.
Strange as it may seem, the worst disease in the world is
malaria. It has been estimated that this disease alone costs
the South $2,000,000.00 per year in loss of human efficiency.
In India it is responsible for the death of 1,000,000 persons
each year. Malaria is produced by a one-celled animal para-
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SCIENCE IN AGRICULTURE
site of which three or four species are infectious to man. These
are Plasmodium vivax, Plasmodium falciparum, Plasmodium
malariae, and possibly a fourth species called Plasmodium
ovale.
The malaria parasite has two separate and distinct life
cycles. One of these occurs in the blood stream of man and
a few of the higher vertebrates, and the other occurs in the
body of a mosquito. The mosquito may, therefore, be referred
to as a carrier of malaria. The mosquito most often incrim-
inated in the transmission of this disease is Anopheles quad-
rimaculatus. However, various other species of the genus
Anopheles (such as A. crucians, A. punctipenis, etc.), are
known to be carriers.
There are parasitic plants which fasten themselves in the
skin and produce irritation. Ringworm, thrush, alopecia, and
a number of other diseases are caused by plants.
The study of medicine has been mostly empirical-by ex-
perimental observation-and with very little scientific basis.
Most of the advance made in scientific medicine is the result
of the discovery of the germ theory of disease, and this dis-
covery is due to bacteriology. The science has borne its most
beneficial fruits in the line of preventative medicine and
hygiene.
In contagious diseases what is needed is a germicide that
is harmless to the human body and that can be introduced
into the circulation. Pasteur said that each contagious dis-
ease is caused by a pathogenic germ or germs which may be
identified. He predicted that a universal germicide would
be discovered, harmless to human beings, and that thereafter
no one need contract disease by infection, and that contagion
would be impossible in the presence of such an universal
germicide.
Inasmuch as a germicide that would destroy plant germs
might not destroy animal organisms, it might not be possible
to have a universal parasitic specific. But if a germicide can
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PLANT AND ANIMAL LIFE
be found that is harmless to animal organisms, but which
destroys all vegetable germs, it would mark the greatest
stride in remedial science. The production of such a germicide
is claimed for the invention of William John Knox of Ann
Arbor. It produces scientifically a germicidal vapor which is
respirable. It is a chemical product produced by a union of
ozone and vapor of pinene. Atmosphere is introduced into the
machine and dried, coming in contact with electric volts
gauged to rule; when ozonized and vaporized it is expelled in
the form of vapor, the formula of which is CI'Hw60:--a gaseous
pinene ozonide.


The Struggle Between the Higher and Lower Orders of Life

Man is destined to struggle for his existence and the attain-
ment of his desires. It is by struggle that he advances. The
more complex the civilization the more strenuous the struggle.
Only the primitive barbarian has no complex problems to
worry him. The absence of difficult problems indicates a
primitive society. The capacity of the human race to support
themselves in great numbers in a given territory is dependent
upon a complex social compact and efficiency of efforts. The
wider the circle of man's activities the stronger the conflict
between mankind and nature.
The struggle between man and the microscopic organisms
of the living world has become intensified many fold during
the last century. The intensification has been brought about
by the spread of parasites and the diseases which they pro-
duce on the animal and vegetable kingdoms. This spread
has been accentuated by the universal exchange of commodi-
ties and the migration of people from clime to clime.
But for some friendly help automatically furnished by certain
of the feathered tribe and other consumers of worms and in-
sects the struggle would have been vastly intensified. He has
[75]





SCIENCE IN AGRICULTURE
not always appreciated these helpers in the struggle for
existence.
It is not much trouble for man to rid the community of wild
game of the larger kinds, that are a menace to him or his
crops and domestic animals, but when it comes to dealing
with the microscopic living world the struggle is shifted to
an entirely different field. Although he has among these
some which contribute to his welfare there is enough of the
injurious kind to render it necessary for him to be of grave
concern.
In the outlines which have preceded the attempt has been
made to place before the reader a comparative analysis or
classification of living things, so as to make it easy to see the
relationship of living creatures to man's welfare. Knowing
this, it will be easier to protect plants and animals from the
inroads of their enemies. The pursuit of this task is more
interesting as we understand the characteristics and life habits
of the underworld which we must combat.
There are 300,000 species of insects already classified, and
several times as many not classified. A large per cent of these
is parasitic-pestiferous as to plants or animals, or both.
There are 400,000 species of vegetable parasites classified.
A considerable per cent of these infest plants or animals, or
both.
The distribution of these enemies of life is so nearly uni-
versal and their operation is so continuous and destructive
that they constitute man's greatest economic and physiological
menace. Millions of dollars must be spent annually to combat
the enemies of vegetation and other millions to combat the
enemies of animals and of man.
Man has enough to enlist all his fighting energies if he
keeps back the armies of untold millions and billions which
are continually attacking him personally and the sources of
his means of a livelihood. Only by constant vigilance and
the help of science and the art of employing efficiently the
[76]




PLANT AND ANIMAL LIFE
most destructive agencies to the myriads of creatures which
are a menace to the vegetable and animal kingdoms which
minister to the welfare of mankind can the race survive in
the struggle for existence.


[77]








I.


Japanese Beetles




XII


FUNGI

T HERE are innumerable parasites of both
the animal and vegetable kingdoms.
There are parasites that prey upon their vic-
tims from the inside and others that operate
from the outside. There are animal parasites
that prey upon animals only and others that
prey upon vegetables only and some that
prey upon both.
Fungi are vegetable. Some are parasitic
and some are not. Some are poisonous and
some can be eaten as food. Fungi include a
large group of plants devoid of green color-
ing matter chlorophyll) and reproduced by
spores. This characteristic renders them un-
able to synthesize carbohydrates. However,
there are certain non-chlorophyllous organ-
isms separated from fungi and regarded as
independent groups. The estimated number
of species is 100,000, but no definite number
has been determined.
The growing requirements of fungi are
essentially the same as those of higher plants:


[79]




SCIENCE IN AGRICULTURE
they require water, inorganic salts, carbona-
cious and nitrogenous ingredients of vary-
ing degrees of complexity. They take in oxy-
gen and liberate free carbon dioxide. The
absence of chlorophyl makes them depend-
ent on outside supplies of organic carbon,
and in many cases, of organic nitrogen.
Fungi are compelled to live on materials
derived from other plants or animals, and are
either parasites drawing their substance from
living organisms or are saprophytes living on
their dead remains-as mushrooms. A fun-
gous parasite may exist as a saprophyte-
most of them are saprophytes. Fungi and
bacteria are the great agents of decay in
nature. The harmful ones are those that cling
to food and that feed on animal flesh. All
decaying fruits, meats and vegetables are a
habitat for fungi. Most of them are poison-
ous, some have medicinal and some econom-
ical uses: Claviceps purpurea is used for ob-
stetric purposes. Some varieties of mush-
rooms are edible. Their cultivation is quite
an industry in some countries. The fungi
most important from an economic standpoint
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FUNGI
are the yeasts. They are of value in ferment-
ing various sugars. Brewing yeasts are used
in bread-making, and in the changing of al-
cohol into vinegar. The three main groups
are of technical value only to the scientist.
The study of plant pathology reveals a
wide range of fungi that are damaging to
fruits and vegetables. They can best be
destroyed by extreme heat or cold. They can
be destroyed by certain chemicals applied
either in a liquid or powdered form. A few
of the fungi pests to crops are smut, rust,
moulds, mildew, scabs, citrus canker, and
some of the blights. This last is also caused
by certain bacteria. Sprays for fungi are
Bordeaux mixture, lime sulphur, sulphur dust,
copper sulphate, corrosive sublimate.
Fungi also cause diseases of animals. The
following are some of the diseases of man
that are caused by fungi: Athletes foot, Favus,
Otomycosis, Blastomycosis, Bronchomycosis.
Millions of dollars are spent annually by
farmers in the leading agricultural countries
of the world fighting insects, bacteria and
fungi. Man's existence on the earth is dis-
[81]




SCIENCE IN AGRICULTURE
puted at every turn by these enemies of both
plant and animal life. It is much easier to
master the elements of nature than it is to
master the living world.


[82]




XI
FILTERABLE VIRUSES

THERE is scarcely any adult person who
has not at some time known something of
the ravages of the more common diseases,
influenza, colds, mumps, measles, trachoma,
varicole, vaccina, herpes, warts, rabies, in-
fantile paralysis, Rift Valley fever, yellow
fever, smallpox, Chorio-meningitis, psitta-
cosis and dengue fever. The astonishing
fact remains, however, that the nature of the
causative agents of these and many other
similar diseases is, as yet, unknown, for these
are some of the filterable virus diseases.
As far as is known, filterable viruses are
both living and non-living. They represent
the beginnings of life, and are at the same
time the last stages of parasitic degeneration.
They may be enzymes, they may be by-prod-
ucts of cellular metabolism, or they may be
ultra-microscopic living organisms. The facts
are that nobody has ever seen a virus, nor
has any one ever obtained one in a pure
state. Viruses have been grown experiment-
ally on laboratory media, but they grow only
[83]




SCIENCE IN AGRICULTURE
in the presence of living cells and nothing
whatever is known of their methods of growth
or reproduction.
Viruses are, for the most part, character-
ized by the fact that they will pass through
any known type of filter. The most common
type of bacteriological filters are constructed
of "diatomaceous earth." They are tube-like
in appearance and brick-like in composition.
The walls of the filters are porous enough to
allow a liquid to pass through them, but are
small enough to stop any organism which is
large enough to be seen with the most power-
ful microscope. Filterable viruses are not
stopped by these filters, but pass through
them as though they were liquids. This has
led many investigators to the conclusion that
they are purely chemical in nature and are
non-living.
However, the fact that viruses cannot be
successfully preserved or propagated, except
in the presence of living cells, points to the
conclusion that they are living organisms
dependent upon living tissue for their live-
lihood.
It has been demonstrated that the entities
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FILTERABLE VIRUSES
composing these powerful agents of disease
are so small as to approach the size of one
molecule of living protein. Since the mole-
cules of even the largest protein substances
are much too small to ever be seen or photo-
graphed by any means known to modern
science, it remains unlikely that the true na-
tures of filterable viruses will ever be deter-
mined by any method of direct observation.
The rays composing the light waves of even
X-rays and cosmic rays are so far apart that
they will not accurately reflect the image of
one molecule of protein.
One of the most brilliant men in bacterio-
logical research in many years was the great
Japanese, Noguchi. He shared the belief of
many other investigators that when an ani-
mal was killed by one of the virus diseases,
the virus itself died immediately. Relying
upon this belief, he handled some monkeys
which had been killed by the yellow fever
virus. Subsequently, however, he contracted
yellow fever and science was bereft of a great
genius. His death, however, proved that
viruses may live on dead animals for at least
a short period of time.
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SCIENCE IN AGRICULTURE
Viruses are transmitted from one individ-
ual to another in a great many ways. Those
causing colds, influenza, infantile paralysis,
etc., may be transmitted through the air on
minute droplets of water. The yellow fever
virus, on the other hand, is transmitted
through the bite of certain mosquitoes. Oth-
ers may be transmitted by direct contact.
Most of the viruses stimulate mechanisms
of immunity which are lasting in individuals
who recover from an initial infection. Thus it
is that individuals almost never contract such
diseases as measles, mumps, infantile pa-
ralysis and smallpox more than once. Un-
fortunately, however, this lasting immunity
does not always follow an initial infection,
and there is, therefore, no limit to the number
of times a person may have colds, or influ-
enza, etc.


[86]





XIV


FOOD AND HEALTH

ANEW science is looming up to challenge
human ingenuity-the relationship of
health to soils. Physical man is made up of
ordinary physical elements, organized ac-
cording to a definite plan by the human life
principle. Science has discovered ninety
distinct elements; less than half this number
are known to exist in the human body. It is
not known just how many of these elements
should exist in the human body, or in what
proportion. The puzzling thing about it is
that one can live without a full supply and it
may live with some which it does not need.
However the power of endurance is con-
trolled by the presence of the needed ele-
ments and substances in proper form and
proportion.
We eat the solids, drink the liquids, and
breathe the air which are utilized to build the
body and keep it in running order. If these
sources of supply are lacking in the ingredi-
ents which they are supposed to contain then
it follows that the physical organism will lack
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SCIENCE IN AGRICULTURE
some of the things it should have. The soil
from which food grows must have the min-
erals required or a "balanced ration" or a
"square meal" will be a misnomer as it will
be neither balanced nor squared with the
requirements of the inner man.
A large per cent of the cultivated soils of
the earth are unbalanced in food contents.
Plants can get out of the soil only what is in
it in available form. Animals can get out of
plants only what the plants have in them.
All of which means that one may gradually
starve although furnished with well-cooked
foods of variety and in plentiful quantity.
Salt is the only mineral which we must use
direct and not through vegetation. We get
a modicum from the meats of animals who
have access to salt. Refined salt lacks min-
erals which should be allowed to remain in it.
Minerals taken into the system through
plant foods are more available than are min-
erals taken separately. Iron tonics are not as
effective as iron in green vegetables. How-
ever, it has been proven that prepared min-
erals mixed with feeds given to live stock are
beneficial. Stock feeders often buy prepared
[88]




FOOD AND HEALTH
minerals and feed beef cattle with a mixture
of regular feeds and minerals and get re-
markable results. Some soils are totally lack-
ing in lime. Animals need lime to make bone
and teeth. Lime is not a fertilizer but it is a
plant requirement. Lime is not a food but it
is a requirement in all animals possessing
bones. Some soils need "doctoring" to pro-
duce certain vegetables.
Commercial fertilizers are made up of nitro-
gen, phosphoric acid and potash in varying
proportions. The assumption is that all other
mineral elements are always in the soil in
sufficient quantities to meet the needs of
growing crops. This assumption is gratuitous
and without foundation in fact. All these ele-
ments and ingredients may be in soil and
bountiful crops be produced and yet there
may be a total lack of the minor but essential
things that go into foods for man. There are
soils so peculiarly constituted that they need
minerals that are in no sense of the word fer-
tilizers. Some need copper sulphate, some
manganese, some lime, etc. Doctoring soils
is as yet purely empirical-by experiment-
and not by an established science.
[89]




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