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UNIVERSITY
OF FLORIDA
LIBRARY
Course in Conservation
of Florida's Soils
for FLORIDA HIGH SCHOOLS
SOILS
*.*. *. .
State Department of Public Instruction
Tallahassee, Florida
COLIN ENGLISH, State Superintendent
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FOREWORD
This is one of the several bulletins prepared and issued by the
Department of Public Instruction in compliance with Sections
5-6 of Senate Bill No. 562 enacted by the Legislature of 1935
and relating to Courses of Instruction covering the Conserva-
tion of the Natural Resources of Florida.
It has been planned to use the material contained in the
pamphlets in connection with the Courses in General Science,
Advanced Civics and other courses, without provision for a
separate course carrying credit, in the Conservation of Natural
Resources.
The soil antedates even the most ancient forests. It is the
heritage of all life, the source of food, the beginning of wealth
and the basis of civilization. It is a cradle for the seed, sustenance
for the growing plant, and a grave for the dead. When the
soil loses its fertility, empires decline and nations crumble.
Truly the soil is man's most precious natural resource and
should be approached with reverence.
Strange as it may appear, the salt of the ocean and food for
fish come directly or indirectly from soil. Although the ocean
and other bodies of water furnish a portion of man's food, this
is comparatively small, even for people living near the shores.
The greater part of man's food is grown on the soil.
Since the land is the source of food and the basis of all
wealth, it behooves any nation whether young or old to give
serious consideration to soil conservation. This is not a new
problem. It has been practiced in a limited way by some farm-
ers in American for more than a century, and in China and
Europe for many centuries.
The materials contained in this bulletin were prepared for
the State Department of Agriculture by Dr. 0. C. Bryan, Pro-
fessor of Soils, at the University of Florida, in the belief that
one function of the public schools is to acquaint future citizens
with important problems affecting the welfare of society. It is
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hoped that these pages will aid teachers and students in making
a worth while study of the conservation of the resources of
Florida's soils.
An effort has been made to print and distribute a sufficient
number of copies to furnish each high school library with at
least ten copies for the use of teachers and that of pupils en-
rolled in the subjects above mentioned.
The office of the State Superintendent of Public Instruction
is deeply indebted to the administrative officers of the several
departments of the State Government concerned with the Con-
servation of Natural Resources for their active and valuable
cooperation in the preparation of these pamphlets.
KINDS OF SOILS
Soils are different in many ways, the most outstanding of
which are variations in color such as gray, brown, red, and black:
variation in size of particles such as gravel, sand, silt, and clay: (1)
variation in topography such as level, hills, or mountains: varia-
tions in parent material such as limerock, sandstone, clay, granite,
marble, and others: also variations in moisture, whether wet
or dry. One or more of these variations may be observed in
any community and is reflected by the differences in native
vegetation and crop production. In fact, these variations ac-
count for the wide variety of plant life which we see about us.
The average person may recognize that soils differ in their
ability to grow plants, but he seldom understands how or why.
Close examination shows that soils are made up of many small
particles which vary in size and color. Sand particles vary
from about the size of a pin head to fine powder, while clay
particles cannot be seen with a microscope. Particles as large
as sorghum seed and larger are called gravel, while those in-
termediate between sand and clay is silt, which has a floury
feel. When soil is rubbed between the fingers quite different
characteristics are noted in different soils. Sands have a gritty
feel between the fingers, while clay particles are very fine and
smooth, with a sticky and plastic feel when wet. Although
all soils contain some sand, silt, and clay, the different soil
grades or classes commonly referred to as sands, loams, and
clays, merely contain different proportions of these ingredients.
Each of these class names has subdivisions such as coarse sand
and fine sand, sandy loam, silt loam and clay loam. Soils with
eighty per cent or more of the sand ingredient belongs to the
sand class. If a soil contains over fifty per cent of the clay
ingredient it is a clay soil while the loams contain from twenty
to fifty per cent clay and silt ingredients. Further examination
of a soil shows that the surface is usually darker than the sub-
soil which often exhibits distinct layers or strata. These may
be seen along roadside banks or ditches. (These layers are
illustrated for two Florida soils in Plate I.) The nature of
(1). Gravel-1 to 2 mm. in diameter. Silt-.05 to .005 mm. in diameter
Sand-.05 to 1 mm. in diameter. Clay-below .005 mm. in diameter.
PLATE I
(Upper)-A road cut showing the different soil layers in Orangeburg
fine sandy loam.
(Lower)-A ditch hank showing the soil layers in Leon fine sand.
(Note the layers in both soils.)
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these different layers is very important to agriculture. Soils
which have a brown hardpan stratum underneath the surface
are quite different from those having a clay or sand under-
neath. These layers serve as a basis of classification and nam-
ing of soils.
Among the other important soil variations are differences in
available plant food elements or fertilizer nutrients such as
nitrates, phosphates, potash and others. These variations are
inherent properties of the soil and further explains why some
areas are productive and others are not. Many plants grow
normally without the aid of man, but most of our economic
plants require special cultivation and care for satisfactory pro-
duction. Such crops as corn, cotton, sugar cane, beans, cab-
bage, celery and tomatoes require a certain amount of inter-
tillage, sometimes referred to as cultivation, while oats, barley,
rye, clover and such crops, planting is the essential operation.
Tree crops do not require as much tillage as annuals.
Crops which require inter-tillage or cultivation are usually
hard on the soil. When the land is plowed and changed from
its natural condition it is more subject to erosion and leaching
losses. Cultivation increases the rate of availability of the plant
food elements, thereby increasing the productive power of the
soil. But it also opens the way for erosion losses as may be
seen on the slopes of many farms in the South. (See Plates
II, III, and IV)
EARLY FARMERS USED POOR SOIL CONSERVATION
MEASURES
During the early history of America, most crops were grown
without a great deal of regard for soil conservation. Land was
cleared and cropped until the surface soil had become depleted
and often eroded; then new land was acquired and the process
repeated. This type of farming has resulted in the loss of so
much of the soil, largely through erosion processes, until at
the present time over fifty per cent of the cultivated land in
the United States has been affected by erosion losses. It has
been conservatively estimated that over fifty million acres in
PLATE II
(Upper)-Small gullies in a field showing the result of poor soil
management.
(Lower)-River showing soil washed in from hills and fields similar
to upper condition.
(Courtesy of Soil Conservation Service, U. S. D. A.)
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PLATE III
(Upper)-View of sheet and gully erosion. Market peanuts in back-
ground. (Note the absence of ground cover.)
(Lower)-View of small gully erosion after peanuts were stacked.
The barren soil is subject to erosion common in West Florida.
(Courtesy of Soil Conservation Service, U. S. D. A.)
PLATE IV
(Upper)-A gully ready to undermine farm buildings.
(Lower)-Method of controlling gully erosion. The log dam prevents
further deeping of channel. (Note soil collected in gully channel.)
(Courtesy of Soil Conservation Service, U. S. D. A.)
the United States have become so severely eroded that farming
is no longer profitable. (See Plates II and IV.) Unless some
measure is taken to conserve the surface soil, other areas will
be destroyed and the prosperity of our nation seriously affected.
China faced this problem several centuries ago, but failed to
control erosion losses, with the result that much of her country
is now desolate.
In recognition of the magnitude of soil losses facing the
American people, the National Government, through its soil con-
servation service, has undertaken to bring about sane and prac-
tical conservation measures through out each state.(2) This
service is intended to reach every rural community and educate
all classes of people regarding the basic nature of the soil and.
the importance of conserving the surface layer through better
farm practices. If the surface soil can be maintained, our nation
will be more permanent and our farm people more prosperous.
SOIL DEPLETING CROPS
When crops are sold from the farm, part of the plant food
in the soil is removed and eventually the soil becomes so de-
pleted that profitable crops can no longer be produced. Where
crops are thus sold from the farm they are designated as soil
depleting crops. The following crops are "soil depleting",
corn, (including broom corn and sweet corn), tobacco, cotton,
potatoes,. rice, sugar cane, commercial crops and canning crops,
(including melons, cucumbers, and strawberries), peanuts, if
harvested, grain sorghum and millet, small grains such as wheat,
oats, barley, and rye when harvested for grain or hay and soy-
beans when harvested, or any crop sold from the land.
SOIL CONSERVING CROPS
If the crops should be grazed, the soil is not depleted of so
much of its plant food. Such crops are known as soil conserving
crops and are so indicated as follows: Annual winter legumes,
(including vetch, winter peas and clover); perennial legumes,
(including alfalfa, kudzu, and sericea); summer legumes, (in-
(:). Graceville, Florida is the headquarters for the soil conservation
projects in Florida. (U.S.D.A.)
eluding soybeans, velvet beans, crotalaria, cowpeas, and annual
'varieties of lespedeza) ; peanuts when pastured, perennial grasses
such as centipede, Dallis, Bermuda, and carpet grass; winter
cover crops, such as rye, barley, oats, and small grain mixtures.
Furthermore tree crops planted since 1934 are designated as
soil conserving crops.
SOIL IMPROVING CROPS
Experience has taught that some plants may even improve
the soil by preventing leaching or erosion losses or by securing
through the roots atmospheric nitrogen. Such crops as cow
peas, velvet beans, crotalaria, beggar weed and clover, are gen-
erally known as leguminous plants. They are often grown as
cover crops and when they, or any other crops are grown especial-
ly for the purpose of improving or conserving the soil, without
being grazed or sold, they are designated as soil building crops.
SOIL EROSION
Although losses through leaching processes and the sale of
crops reduce the natural productivity of the soil, by far the
greatest soil loss is erosion. The annual erosion losses of plant
food in the United States has been conservatively estimated at
four hundred million dollars ($400,000,000) annually. (3) It is
further estimated that the aggregate loss in terms of plant food
soluble and potentially soluble is sixty times that of the nutrients
added in fertilizers. (4) (See Plates II, III,. and IV.)
While erosion may be caused by either wind or water, that of
water is more general and more severe than that by wind. In
both cases the losses usually begin when the native vegetation,
either grass or trees, is removed. (See Plates III, and IV.)
Wind erosion is most severe in arid regions where the native
sod has been broken as in the Dakotas and other western states.
From a national standpoint the grass sod is more important
for agriculture than cultivated crops in such regions. Breaking
the sod reduces the binding properties of the soil and permits
severe wind erosion and even water erosion during certain
periods of heavy rainfall.
('). Circular 33, Soil Conservation Service-U.S.D.A.
(4). United States Department of Agriculture. Yearbook 1934.
In humid regions practically all the cultivated slopes are sub-
ject to erosion. This may be observed in the hill region of
Northwest Florida. The soil losses from erosion are usually in
proportion to the degree of the slope of the land. In many
instances, improper management of soils with five and ten per
cent slope has resulted in the loss of the first five to six inches
of soil during one generation.
KINDS OF EROSION
Soil erosion is grouped under two general headings. 1. Sheet
erosion, which consists of the movement of water carrying soil
over the surface in a manner not unlike a sheet. (See Plate
III.) While this type of erosion usually is the most severe,
it is not as conspicuous and often passes unnoticed. 2. Gully
erosion, which is very destructive when once started. (See Plate
IV.) Gullies may start in a rather small and inconspicuous way
as a result of plow furrows, trails, and road ways, and within
a few seasons become so severe that the land cannot be used for
crops. Often times farm buildings are in danger and some-
times are undermined by the progressive action of gullies as
shown in Plate IV. Cotton and corn farmers should exercise
precaution in the running of rows in contours and in the use
of terraces on slopes. A management progranr that will reduce
the surface soil losses to a minimum is the most profitable prac-
tice. If this is not done, the cultivated slopes will lose their
natural fertility. While this takes place gradually, neverthe-
less it is certain and the owner will probably find his farm under
mortgage because of its inability to produce crops properly.
Such areas have poor schools and inexperienced teachers. (See
Plate V.)
SOIL LEACHING
Another form of soil loss, though not conspicuous, but never-
the-less serious, is known as leaching which takes the soluble
part of the soil nutrients downward with moving water. This
is a downward washing of the available soil nutrients. The loss
80
PERCENTAGE OF
ONE ROOM COUNTY SCHOOLS
60
50
40
POOR SOIL AREAS RICH SOILAREAS
PLATE V
Showing the percentage of one room schools, and in-
experienced teachers on poor soil compared to rich
soil.
(Courtesy, Tennessee Valley Authority.)
is most common in sandy lands of humid regions. The greater
part of Florida would come under this type of soil losses- The
losses are so great that a high tonnage of fertilizers are used
annually in Florida soils.
CONTROL MEASURES
For many years certain American farmers have devised some
erosion control measures in their own individual ways. Some
of these measures have been partially successful. The construc-
tion of elevated ridges or terraces in the field to control erosion
has been practiced for many decades. On the whole the farm
people have not been financially able to construct proper ter-
INEXPERIENCED
TEACHERS
(County tlemfstdrySc&A os 1933)
IS
15 -
12 -
9
6
3
PER
RICH SOIL AREAS
PLATE V
Showing the percentage of one room schools, and in-
experienced teachers on poor soil compared to rich
soil.
(Courtesy, Tennessee Valley Authority.)
races on stiff and heavy soils because of insufficient power on
the farm. Such soils are usually most subject to erosion. This
may be seen in the rolling piedmont areas of the cotton belt
where erosion has destroyed millions of acres of farm land.
(See Plate VII. Upper right.) The sloping lands in West Florida
are also subject to serious erosion losses.
Erosion control measures consist very largely in keeping the
vegetative cover on the land as much as possible. This means
that those crops which are most aggressive are the most useful
in soil conservation. Grasses are soil binding plants and are
among the most effective soil conserving crops. Areas with a
slope of more than fifteen per cent should be retired from culti-
I.
II I
IP L AREAS
POOR 501L AREAS
I
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PLATE VI
(Upper)-Terracing machine in operation. (Note depth of furrow
made by machine.)
(Lower)-Terraces completed in field. Properly constructed terraces
remove excess water without erosion loss.
(Courtesy of Soil Conservation Service, U. S. D. A.)
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vated crops and planted to either trees or sod producing crops
(pastures). The best gully control measure is a preventive
through the use of sod, brush, contour farming and terraces
to either hold or divert the water from the gully channel.
Any kind of aggressive plants, especially those that will bind the
soil such as grasses and vines as well as locust and pine trees,
will control gully formation. In most cases the sod forming
crops are more effective than tree crops within short periods.
(See Plate VIII.)
Any practice that will break the sod and permit the impact
of rain to agitate the soil, will increase the erosiveness of the
soil and in the long run should be done with care. In other
words, plowing and harrowing prevents the weeds and grass
from covering the land and allows the rain to agitate the soil,
permitting water or wind to carry off the finer particles or cream
of the soil. This is emphasized on land where cultivated crops
are frequently grown compared to grass land. The comparative
losses under different management may be seen in Plate VIII
(Lower right). This graph represents soil losses over a six
year period in Missouri.
For those crops which require inter-tillage, it is necessary
to construct terraces. (See Plate VI.) This is done with tractors
and terracing machines in all soil conservation regions. In
some cases teams are used to construct terraces. Then to further
control erosion the inter-tilled crops are arranged in a strip
crop fashion with those that do not require tillage. These strips
or non-tilled crops serve to hold any soil material that may wash
from the plowed areas. (See Plate VII.) As a further measure,
crops are rotated in such a way that intensively tilled crops
will not be on the same area every season. In many instances
it is necessary to use commercial fertilizers to stimulate a cover
on eroded soils. This is usually a profitable measure in the long
run.
It is very desirable to keep all soils covered with plants as
much as it is practical; where land is too steep for cultivated
crops, trees should be planted. Any kind of plant or cover
on the land will materially retard erosion losses as well as leach-
PLATE VII
(Upper)-Terrace arrangement on a fairly steep slope.
(Lower)-Strip farming on a steep slope.
(Courtesy of Soil Conservation Service, U. S. D. A.)
PLATE VII
(Upper)-Erosion on poorly managed farm in the cotton belt.
(Lower)-Terraces and strip farming using cotton and peanuts in
Florida.
(Courtesy of Soil Conservation Service, U. S. D. A.)
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ing losses. (See Plate VIII.) In the first case it is a problem
of preventing the solid portion of the soil from being washed
away. In the second case it is a problem of preventing the
soluble portions of the soil, commonly referred to as fertilizer
nutrients, from being leached. Therefore, plants will either bind
the soil particles together or absorb the available soil nutrients
and convert them into a less leachable form. Thus the sandy
land will be benefited and conserved by the use of crops whether
weeds, grass or otherwise. It is even necessary and profitable
at times to bring in litter from outside to serve as a soil cover
as well as to increase the moisture holding capacity of the soil
for the main cash crop. This is particularly true in a warm
humid climate such as Florida, where the conditions are favor-
able for the soil organisms to render plant food available during
the entire year. In such areas weeds or grass are often a
blessing in disguse to the soil. Under Florida conditions the
natural forces have tended to equalize soil losses and we have
a number of very profitable volunteer crops such as beggar weed,
native grasses, and other crops that grow after the cultivation
of the cash crops have been discontinued. This is nature's way
of replenishing her land and should be encouraged wherever
possible. The value of this farm practice has been observed
by many farmers.
One of the most serious problems involved in the management
of organic soils, such as peat and muck, is the fact that they
shrink and burn readily when dried. Since organic soils con-
sist very largely of plant materials, bacteria and fungi decom-
pose them readily when once exposed to atmospheric conditions.
Moreover, when dry, they will burn rather freely. So the prob-
lem confronting the Florida Everglades is that of moisture con-
trol. By moisture control is meant sufficient moisture through
drainage and canal systems to prevent fires and excessive de-
composition process and at the same time to drain the excessive
water so that crops may be grown. It is just as important to
consider this as a soil conservation measure as erosion control.
Where land for any reason (sand, gullies, or what not) is
not suited for cultivated crops, it should be planted to tree crops
or grazing crops, both of which are soil conserving. Such a
PLATE VIII
(Upper)-Lespedeza sericea less than two years old. This crop makes
good ground cover and hay.
(Lower)-Velvet beans and sorghum. Makes a good cover and hay
crop.
(Courtesy of Soil Conservation Service, U. S. D. A.,
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so.
20,
Plowed4" Plowed8" Continuous Continuous Rotation Continuous
Followed Followed Bluegruss Wheat Corn
PLATE VIII
(Upper)-Centipede grass set only two months using small squares
of sod. This grass makes good ground protection.
(Courtesy, Soil Conservation Service, U.S.D.A.)
(Lower)-Graph showing the effect of different treatments on
erosion. (Note the small annual loss of soil under continuous
grass.)
(Courtesy, Mo. Agr. Exp. Station, Res. Bul. 177.)
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PLATE IX
(Upper)-Longleaf pine reseeding.
(Lower)-Florida cutover land with no seed trees left. Land allowed
to burn annually.
SI
practice as burning of the forests damages the trees so severely
that they can rarely become established. Many Florida wooded
areas have been cut almost bare of pines with the result that
much of the land in the state exists as is indicated in Plate IX.
SUMMARY
While Florida soils are not subject to severe erosion losses
except in the hilly sections of the central and the western counties
they are subject to severe leaching losses because of their sandy
nature. Clay subsoil prevents leaching. This problem is as serious
as the erosion problem, and can be considerably improved by
using crops that keep the land covered as much as possible.
Nature's way is often better than man's way.
Soil conservation is a constant problem with the state and
nation as well as with the individual farmer. Plans are to be
made and executed each season and year regarding control
measures, such as building or repairing terraces, contour plow-
ing, planting tree crops, cover crops, repairing gullied areas,
seeding pasture areas and all other practices that will conserve
the land. Unless we save the soil, not only the farm people but
the nation as a whole will be confronted with greater difficulties
than they are now facing.
SUGGESTED EXERCISES FOR CLASS STUDY
1. Visit five farms in your community and ascertain the kind
of erosion if any-sheet erosion, gully erosion-how much
soil lost? Compare field with nearby forest area.
2. Collect some garden soil and place two teaspoonfuls in
a tall bottle or cylinder with fifty times this amount of
water and shake thoroughly and allow to stand one min-
ute. Then pour off the liquid leaving the sand in the bot-
tom. Repeat this operation by adding more water five
times and note the difference in color of washed soil from
that of original. (The best part of the soil has been
washed out).
3. Take three to five designated fields in your community
and get their history for the past five years regarding
crops grown. Then classify the crops as soil building,
soil conserving, or soil depleting. Note the influence
they have had on the fertility of the soil.
4. Examine the soil by digging with a shovel or post hole
digger in three productive fields and three unproductive
fields, noting color, depth of surface, amount of clay in
the subsoil and hardpan, if any, in the soils.
5. If any rocks can be located in your community, examine
them from the standpoint of color, origin, composition,
degree of hardness, and degree of weathering.
6. Make a survey of your community and find out the num-
ber of farms that are being rented and compare to those
being farmed by their owners. Which are more produc-
tive and why?
7. Examine with a spade a pasture sod, and forest area, and
compare the condition of soils with that of a cultivated
field. Explain which would be most likely to erode.
8. Contact several farmers to ascertain the value of allow-
ing the land to rest or remain idle as a means of improv-
ing its fertility.
9. Mix some green legumes or other plants with a moist
soil and examine at weekly intervals noting the changes
taking place and rate of decomposition.
10. If available, study the influence of slope and kind of soil,
whether clay, sand or loam, on the severity of erosion.
11. Is erosion aggravated in Florida by heavy freezes as in north-
ern states?
Soil Conservation Paramount
To stimulate a non-political, soil-building program resolves it-
self into two phases-first, intelligent self-help and, second, finan-
cial aid from appropriate Governmental authorities where badly
eroded farm lands and impoverished grazing areas should be with-
drawn from agricultural use, temporarily or permanently. The im-
perative necessity for this is illustrated in Fig. 6.
.... ..... ".
:. \ "-.. .-
In the long run, protecting the American Market for the Ameri-
can farmer should so increase his net income that normally he will
have an adequate reserve to buy fertilizer and plant soil-building
crops without depending on the Federal Government for help. In
this connection attention is called to the fact that rice growers in
GENERAL DISTRIBUTION OF EROSION
7,o fp W.", .l,. ,
SCIENCE ADVISORY BOARD, Second Report
Fig. 6
Degree of soil erosion. The maximum erosion by water, in the form of sheet erosion and
gullying, has taken place in areas 1 and 2, where respectively serious and harmful erosion is
widespread over cultivated and overgrazed areas. In area 3, the relatively flat lands, and in 4,
the hilly and mountainous country of the Northeast and the Pacific Northwest, erosion is gen-
erally not serious, though it is bad locally in area 3. Area 5, in the Great Plains and the
Columbia Plateau, is characterized by wind erosion, much of it serious where the soil is culti-
vated. In area 6, mainly the intermountain West, there is in general much serious erosion
owing to overgrazing chiefly.
Japan expend from twenty-five to forty percent of their annual in-
come for the purchase of fertilizers. This is in a country where
the soil has been under cultivation for tens of centuries. Proper
soil conservation initiated by previous dynasties would have avoid-
ed the necessity for such a heavy expense f.r fertilizers. Let Amer-
ica take notice lest history repeat itself in this country.
To make possible a more secure stake in the land for the tiller
of the soil is of paramount importance. Profitable prices for farm
products plus low interest rates on mortgages will assist the farmer
in devoting a larger amount.of.his current income to the reduction
of mortgage. The increa'e in.fyrn t.nanfy'.etween 1910 and 1930,
Second Derrlborn C('afttreoc. .
.-~. 2 '
. .: .......... ..
as illustrated in Figs. 7 and 8, is an unhealthy situation. Widely
distributed ownership of land, bought and paid for, is far better
than a standing army in maintaining the Republic.
NINETY PER CENT SELF-HELP
The successful application of these remedies is dependent on
ninety per cent self-help and only ten per cent Government aid.
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