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Speeches of Hugh Hammond Bennett
Address delivered in connection with the South Carolina
Teacher-training program by H. H. Bennett, Chief, In Charge Soil Erosion
Investigations, Bureau of Chemistry and Soils, U.S. Department of Agriculture,
at Spartanburg and Clemson College, November 4, 1932; Columbia and Rock Hill,
November 5, 1932.
Lectures on Soil Erosion: Its Extent and Meaning and Necessary Measures of
Control
In order that the thought of the farmers of the country may be more sharply
focused upon the widespread evils and cost of erosion and the necessity for its
better control, it is going to be necessary for those of us who enlist in this
undertaking to orient ourselves with respect to:
- the fundamentals of erosion processes,
- how erosion impairs and destroys farm land,
- the geographic extent of erosion,
- the technique of erosion-control methods, and
- the best methods for presenting these facts to those who must do the
actual work.
The engineering phases of the problem are to be discussed by members of the
staff of the Bureau of Agricultural Engineering.
Part I
The Problem
This country is standing at the crossroads with respect to the problem of
conserving its agricultural lands. There is immediate and vitally important need
for renewed nation-wide effort towards this end. Without further delay the
attention of the country must be focused more acutely upon the seriousness of
this situation, which if permitted to continue will mean inevitable shrinking of
our most fundamentally important asset, the soil, to a point of grave national
danger. Unrestrained erosion, rainwater running wild, is rapidly eating into the
heart of immense areas of farm and grazing lands. While we are not likely to
starve any time soon because of this evil of erosion, farming is going to be
pushed down more and more toward the level of pauperized agriculture resulting
from greatly depreciated crop yields, as the consequence of increased subsoil
farming enforced by erosion-unless in the future vastly more of prevention is
done than in the past. Many farmers already have really reached that level.
In closing our eyes, or in never opening them, to the evils of excessive
erosion, we are to a degree that is becoming increasingly unsafe, foolishly
despoiling the sloping lands of the country by permitting the loss of the
richest part of the soil, the humus-charged topsoil, and after that the better
part of the subsoil. Let's keep in mind that with many types of soil, this thin
surface covering is the very substance of the land, insofar as relating to a
good crop production. Those areas of erosive sloping land comprise something
like seventy-five percent of the arable land of the country. In the Piedmont
region of South Carolina, which embraces almost half the area of the state, I
think we can safely put the area of erosive rolling land at about 85 percent of
the region. All of this is subject to erosion in some degree, while being used
for the clean-tilled crops, as cotton, corn, potatoes and peaches.
Erosion Began With The Clearing Of The First Sloping Field.
Our national habit of ignoring the significant fact that every heavy rain of
summer time, and many of those of winter, takes its toll from the surface of the
ground, its usury of the thin, humus-charged top layer developed by natural
soil-forming processes through ages of rock decay and soil building, began with
the clearing of the first sloping area in the tidewater country of eastern
America This wastage has continued almost without let or hindrance over far too
great a proportion of the country for national safety. It has become a
country-wide menace that must be opposed now with all our fighting capacity,
otherwise the difficulty of control will become greater and greater as the
devastation digs deeper into the more unproductive and unstable subsoil, and
continues to reach out over an ever expanding area, giving us more and more
subsoil farmers with little opportunity, generally, to wrest a satisfactory
living from such stubborn material.
This past summer I had the opportunity of looking over some of the ground
first cultivated by white man in this country, near the site of the first
permanent settlement at Jamestown, Virginia. In this region the flat river
benches and bottoms remain much as they were when those adventurous settlers,
coming over on the God-speed, Sarah Constant and Discovery, began clearing the
plains between the lower James and York rivers, three and a quarter centuries
ago. Much of the sloping areas of the higher watersheds between the major
streams entering Chesapeake Bay is still predominantly poor because of the
wide-spread erosion that began three hundred years ago. Ancient gullies are to
be seen there, some partly healed by reestablished forest, others still deep
enough to furnish indisputable evidence of the truth of an early observer who,
speaking of the rolling areas near the birthplace of America, said: "...
farm after farm ...worn out, washed and gullied, so that scarcely an acre
could be found in a place fit for cultivation."
This recent experience in the Virginia Tidewater country took me back
twenty-seven years to the time when a soil survey was being made of Louisa
County, in the same state, by W.E. McLendon, of Bishopville, South Carolina, and
myself. After arriving in that old Piedmont country, once represented in the
House of Burgesses by Patrick Henry, a letter was received from our Chief, the
late Dr. Milton Whitney, saying that, in addition to the task of classifying and
mapping the soils, he particularly wished, we would exert every effort to
ascertain the cause of the reputed poverty of the lands of Louisa County. After
some weeks in the field we were puzzled over learning that wherever the land had
never been cleared a good depth of mellow loam or sandy loam topsoil was
invariably present; whereas; in practically every sloping field which had been
in cultivation long enough for the stumps to have disappeared neither loam nor
sandy loam was found as a rule, only red clay loam and clay loam. In time we
came to realize the significance of this:
That the original soil had been removed, down to or near the clay that
underlies practically all of the fifty million acres comprised within the
Piedmont region, extending from Alabama to New York City.
It was at that stage of scientific enlightenment that my thoughts went back
over another span of years to a time when I was digging markers with a hoe at
one end of a home-made, wooden horse which my father was using for laying out
terrace lines on his rolling farm in south-central North Carolina. At that
particular time, his laconic reply to my inquiry as to why this was being done
had not impressed me with much vividness. He had said: "We are doing this
to keep the soil from washing away." Subsequently, however, that answer
came to mean very much to me.
Soil Erosion The Most Serious Continuing Farm Problem.
Following the
discovery in Louisa County, it became a part of my duty, as I saw it, to learn
more about this process which could so completely change the character of the
land. Studying the soils in detail in nearly every county of the Cotton Belt and
in numerous other counties, as well as in the various countries of America north
of the equator; two definite conclusions were reached: First, that soil erosion
constitutes the most serious continuing farm problem in the United States; and,
second that no other modern nation of the Western Hemisphere, north of the
equator, is wasting; its agricultural lands as rapidly as the United States,
even though farming has been going in the countries to the south much longer
than in this youthful land of ours. Some time ago it was concluded, also, on the
basis of the available information, that no nation or race within historic time
has been so wasteful of its agricultural lands as we of the United States. To be
sure, vast areas have been laid waste in China, Persia and other old countries,
but those countries used their lands for thousand of years, whereas we have used
the oldest of ours for only about three hundred years, the greater part for only
about forty to eighty years.
A recently evolved theory, based on considerable evidence, is to the effect
that the ancient Maya of Peten, Guatemala, deserted that once densely populated
area because of excessive washing of the soil, coupled with the choking of the
navigable lakes and connecting waterways by deposition of erosional debris.
Although large areas of tropical America are highly resistant to erosion because
of the physical characteristics of the soils, erosion is very destructive in
some parts of these warm regions, especially on the more youthful limestone and
schist-derived soils. Along the southeastern border of Peten I have observed
erosion on limestone clay that resembles the red limestone lands of northwestern
Arkansas, northwestern Georgia, eastern Tennessee and other parts of the United
States. It is quite possible that the same thing took place on an extensive and
disastrous scale in the little State of Peten, where eight million people once
dwelt.
Erosion an Old Problem.
We have been living with erosion for a long time.
Mankind has combated it for unnumbered ages. We have opposed it to some extent
in this country; indeed, we have fought it rather valiantly in some localities,
notably in the southeast, and recently across the Mississippi in Texas, Oklahoma
and Arkansas. However, the real task lies ahead.
Five years ago, A. T. Strahorn, of the Bureau of Chemistry and Soils, found
in Palestine olive trees a thousand years old still living on walled terraces
that were constructed during the Dark Ages. On some of the islands of the
Mediterranean bananas are being produced on terraces of the European type which
are supposed to have been built before the time of Christ. The aborigines in
parts of the Philippines, the Ifugaos and Bontoes, live on rice grown on
terraced strips of mountain slopes, the beginning of whose construction
antedates history. Washington, Madison, Jefferson, Edmund Ruffin and others
clearly recognized the evils of the process. Washington gave up the growing of
tobacco, planted clover and practiced crop rotations on his Mt. Vernon estate in
order to check erosion. You can still see old gullied areas on the lands that
once were his. Some of these are found in close contact with venerable cedars
that must have been there in Washington's time.
In 1913 Jefferson, writing about his farm in Albemarle County, Virginia said:
"Our country is hilly and we have been in the habit of plowing in straight
rows, whether up or down hill, in oblique lines, or however they lead, and our
soil was all rapidly running into the rivers. We now plow horizontally following
the curvature of the hills and hollows on dead level, however crooked the lines
may be. Every furrow thus acts as a reservoir to receive and retain the waters,
all of which go to the benefit of the growing plant instead of running off into
the streams. "
Long ago, Ruffin, one of the best agriculturists the nation has produced,
said that washing of the land was more destructive than all the direct damage
done by crops. But Washington's rotations, Jefferson' s contour plowing and the
terracing (the American type of terrace) which had its beginning about a century
ago somewhere in the Southern Piedmont, failed to stop the wastage; rather,
these methods were employed by too few or with too little efficiency and
persistence to exert any tremendous effect, except in some localities. The vast
majority of farmers went ahead cultivating unprotected slopes until the soil was
swept off or until the fields were spotted with comparatively infertile clay
exposures, then cleared new land. This practice continues to some extent even
today.
Observing the more conspicuous manifestations of soil rushing the gullies
that scar so many slopes, farmers outside the Cotton Belt have occasionally
undertaken some small measure of control, usually in the form of dumping brush,
rocks or earth into the ravines. With respect to the other type of soil washing,
the less conspicuous process of sheet erosion, which is the real giant in the
camp of soil-impoverishing agencies, most farmers living beyond the border of
the Cotton Belt, and far too many living within the Cotton Belt, have been as
soundly asleep as if anaesthetized. In the uplands of a few of the southeastern
states the problem has been recognized and rather effectively opposed, locally,
for nearly a century through the building of really efficient soil saving
terraces. Unfortunately, too many upland farmers either have failed to recognize
the slow depletion of their sloping fields or for one reason or another have
failed to take issue with this most relentless enemy to continuing soil
productivity. Many have failed to maintain their terraces, or the terraces were
not of proper size or grade to begin with.
In most parts of the nation the problem has been almost completely
overlooked. In some states where erosion is about as bad as anywhere, I have
gone year after year checking over soil surveys of county after county without
seeing one single terrace or any other effective measure for slowing down
wastage of sheet erosion. As stated, an occasional farmer was found who had
undertaken at a late stage to check his gullies with brush or stones; but even
these rare efforts generally had the appearance of half-hearted interest, or the
brush or stones were improperly laid and did little or no good. On the other
hand, I have seen on almost countless rolling farms effective measures for
speeding up the process, such as the vicious habit of running rows up and down
the slopes, a practice based on the erroneous conception that ever crop row
should be laid out in as nearly a straight line as possible, regardless of the
consequences. This last error of tillage is a costly practice that the average
South Carolina farmer is not guilty of.
Cause of Lack of Interest.
There was, necessarily, something back of this
general failure of farmers and agricultural specialists to recognize the evils
of unrestrained soil wasting. As I see it, the failure was due, in a very large
degree, to naked ignorance. Somehow the notion got into the heads of too many
specialists, as well as into the pages of publications, .that soil erosion was
an evil confined to the Southern States, to China and other far-away places. An
unfortunate idea, this. From the standpoint of the nation it helped to keep on
the blindfold too long. Some specialists, unaware of the facts, even went so far
as to explain why northern soils do not erode. If they had only looked about the
countryside with seeing eyes they might have educated themselves and made a good
case of the question: Why do some soils of both the North and South erode much
more seriously than others? On the whole, there has been more erosion in the
Southern States because less grass has been grown and because the soils are not
so well protected, in winter, by freezing and with snow blankets. But this does
not mean at all that the problem is not serious in many parts of the North. As a
matter of fact, the loss of 19 1/2 tons of soil per acre by a one inch rain, up
near the Iowa-Missouri line, in 1931, has not been equaled by any measurement
made anywhere else, to date, at least not on land so gently sloping as that was,
the gradient being 8 feet in a hundred, or 8 per cent. And the loss of 26 tons
of soil per acre from eroded land, along with 4l per cent of the rainfall, from
1 4/5 inches of rain falling on land of 16 per cent slope, during August this
year, in west-central Wisconsin, completely smashed all records.
Undoubtedly there is a feeling on the part of numerous people that erosion
belongs to the natural order of terrestrial dynamics. It does, that is, normal
erosion does; but not the kind I am talking about-man-induced erosion, of which
more will be said later. There has, been, then, too much of the point of view
that erosion is a necessary evil that must be borne with Our thought in this
direction has been clouded by the inaccurate conception that our good farm lands
were inexhaustible and limitless. We began thinking this way when this seemed to
be a fact, when a comparatively small population looked out upon the fertile
lands of the eastern empire of hardwoods and beyond over vast expanse of prairie
and plain. We felt the same toward our timber supply and the great herds of
buffalo which were slaughtered for their hides. But we were wrong. Our better
lands have been under cultivation for some time. We can not extend this area,
soil building is too slow; but we are permitting it to be reduced-by excessive
soil washing.
Enormous Area Ruined By Rainwash.
We have found that not less than 17 1/2
million acres of formerly cultivated land have been destroyed in this country by
gullying, and deep washing, or so devastated that farmers can not afford to
undertake its reclamation. In addition, about 4 million acres of bottom land,
formerly cropped, have been rendered essentially useless by overwash, or by
increased overflow resulting from choked stream channels. But these losses,
although comprising a larger area than the total extent of arable land in Japan
proper, are almost insignificant in comparison with the vast area subject to
serious sheet, washing-that slow type of washing which steals a layer of soil
with each successive rain.
Sheet Erosion.
It is unfortunate that most people conclude that where ever
gullies have not developed there is no erosion. This is wholly incorrect. It is
unfortunate, also, that very few thoroughly understand the earmarks of sheet
erosion, even some of our agricultural specialist have not seemed to sense the
viciousness of this form of soil impoverishment. In order to grasp the full
significance of the evil process, it is necessary to know how to identify soil
types and to compare the successive layers of soil of a given area with the
corresponding layers of another area, in order that what takes place in an
eroding field can be precisely checked against what is taking place on the same
soil type, occupying the same slope, or different slopes, in other fields, as
well as in areas that have never been plowed or caused to wash by repeated
burning and over-grazing.
Sheet erosion is that phase of land washing which removes a thin covering of
soil from large areas, often entire fields, more or less uniformly during every
rain, producing runoff. The process goes on slowly, so slowly that its effects
are frequently unobserved until spots of clay and even rock begin to make their
appearance over sloping fields, at which stage, unfortunately, it is usually too
late to fully repair the damage, since it is entirely impracticable to haul soil
back into a field once it has departed on its journey to the sea.
Sheet erosion pursues its course in the direction of soil depreciation, and
even soil destruction, with unremitting persistence, taking its toll of topsoil
with every rain heavy enough to cause water to run downhill, across unprotected
cultivated slopes. We all really understand this, though many of us have not
thought very much about it. We know that rainwater flowing out of fields devoted
to clean-tilled crops is always muddy, never clear. And when we think about it a
second time we come to appreciate the significant truth that this muddy water is
discolored with soil material. It is red, yellow or black, according to the
color of the soil across which it has flowed. Simple mathematics tells us what
must eventually happen where the process is not effectively opposed: The thin
covering of surface soil whittled away, down to much less productive subsoil.
Some soils wash much faster than others, and the steeper the slope the more
rapid the progress of erosion, under ordinary conditions. Some gravelly soils
and porous clay lands (such as the Davidson soil of the Piedmont) are so
absorptive of rainwater that erosion may proceed even slower than on slopes not
nearly so steep. Usually, however, the steeper the slope the greater the speed
of runoff. It has been said: "The power of moving water to scour or loosen
soil. particles varies as the square of the velocity, and the power to transport
this material varies as the velocity. "2 This, of course, refers to ideal
conditions. The actual field conditions are generally highly varied, complicated
by numerous factors. we are not so much concerned with the preciseness of rules
as with the practical facts. Our measurements of soil losses at the erosion
experiment stations are showing that erosion is most severe on the steeper
slopes, with the predominant soils of the country. It so happens, however, that
thus far erosion is proceeding faster from an 8 per cent slope of Kirvin fine
sandy loam than from a 10 per cent slope of Nacogdoches fine sandy loam, with
the same rainfall and treatment, at the erosion station, near TyIer, Texas. We
can for the moment, nevertheless, dismiss these exceptions as representing local
soil conditions that call for special treatment.
Time Required to Build the Topsoil.
According to some of the quantitative
measurements made at the erosion stations, nature requires not less than 400
years to build one single inch of the topsoil of some of our important types of
farm land. This appears to be true, for example, of the very extensive soil, the
Shelby loam, occurring over the rolling parts of the Corn Belt, in northern
Missouri and Southern Iowa. This we have learned by separately measuring the
rate of soil losses under continuous corn production and under a continuous
cover of grass, assuming that land supporting a good grass sod closely
approximates the conditions under which nature developed the mellow surface
layer of the Shelby loam soil, which was largely a grass-covered prairie type in
its virgin state. It takes just seven years under continuous corn farming, in
northern Missouri and Southern Iowa to wash off one inch of the Shelby loam soil
where the slope is about four feet in a hundred, and only one year to remove
this same depth of surface material from land sloping a little more than eight
feet in a hundred. In other words, on land which originally produced in the best
years upwards of 75 bushels of corn per acre, man is now allowing to go to waste
in from one to seven years that which took nature not less than 400 years to
build. The average depth of soil on the average slope of the Shelby loam region
is about seven inches; the clay beneath, which is reached by erosion proceeding
under the present system of farming in from about seven to fifty years, produces
in a good year only about 20 bushels of corn per acre, and often nothing in
poorer crop years.
In 1931, at the Bethany Erosion Station, good uneroded soil, broken out of
bluegrass sod five years previously, produced without fertilizers 51 bushels of
corn per acre; whereas, severely eroded soil which had been cultivated 40 years
produced less than l4 bushels per acre. It is perfectly obvious that no business
could very long withstand such evil treatment. It is not being withstood; I have
recently seen farms on the Shelby loam which were abandoned because of erosion.
In one instance, the owner, when warned that if he did not bestir himself to
stop the soil washing he was going to ruin his farm, replied that his farm owed
him a living and, that he was going to get a living out of it. He failed to do
that, however; he lost his farm and is now living on another man's land. The
farm was so deeply washed that it will not now produce grass; it is a weed farm,
without present value.
Probably in the Piedmont region it took even longer for nature to build up
the topsoil. I would not be in the least surprised if it turned out that not
less than 1,000 years at least are required by nature to build an inch of good,
rich Piedmont topsoil. Measurements now under way will soon give us some light
on the subject.
Importance of the Topsoil.
It seems strange that we have paid so little
attention to the vital importance of the topsoil, the thin humus layer, charged
with decaying vegetable matter, containing the bulk of available plant food and
representing the abiding place of incredible hosts of beneficial
micro-organisms. The soil immediately beneath the leaf-mold of forested areas
often is higher in content of phosphorous and lime than the layers below, it is
often neutral or even alkaline where the subsurface material is strongly acid.
This is due to basic constituents brought up from below by plant roots and
concentrated in this surface layer through the medium of decomposing leaves, and
grass. Our experiment at the erosion stations are showing not only large
decreases in the productive capacity of land following the washing away of soil,
but even impairment of the quality of some of the products grown. Cotton, for
example, has tested much weaker in strength where grown on eroded soil, as
compared with that produced on uneroded soil Immediately alongside; and the
content of oil in the cotton seed much lower-according to results obtained at
the Oklahoma erosion station.
At the Western Kansas Station, on a 5-per cent slope, the 1931 loss of
rainwater falling on native sod was. 05 per cent of the total precipitation,
while the corresponding loss of soil was .0025 tons per acre; whereas, the
losses from clean-tilled Kafir were 11.79 per cent of the rainfall and 20.85
tons of soil per acre. In other words, native sod held back 236 times as much of
the rainfall as Kafir (following wheat) and 8,340 times as much soil. From wheat
grown on slightly eroded soil, the losses were 2.79 per cent of the rainfall and
27 tons per acre of soil; whereas, from wheat grown on severely eroded land
(desurfaced down to the subsoil), 15.43 per cent of the rainfall was lost and
3.40 tons of soil per acre. This means that in the growing of wheat in western
Kansas eroded land (of the extensive Colby silt loam type) is losing 5 1/2 times
as much of the rainfall and 12 1/2 times as much soil as land still retaining a
considerable part of the original topsoil. Grass closely clipped to simulate an
overgrazed condition lost 6 times as much water and 12 times as much soil as the
normal prairie sod. Wheat on normal soil (not deeply eroded ) produced 26.7
bushels per acre, as against only 5 bushels on severely eroded land.
It is more pertinent to the farmers of the Piedmont of South Carolina,
however, to know that at the erosion station near Statesville, North Carolina,
located on red clay loam, of which there is much in this state (287 thousand
acres of the same class of land having been mapped in Spartanburg County alone),
the average loss of soil and water in 1931 amounted to 14 tons per acre and 12
per cent of the total rainfall, respectively, from cotton; and 65 tons per acre
and 26 per cent of the rainfall, from bare ground; whereas, the corresponding
average losses from lespedeza were only 1.5 tons of soil and 10 percent of the
rainfall. Now, from exposed subsoil of the same original type, receiving the
same rainfall and cultural treatment, the corresponding losses, in 1931, were,
from cotton, 17 tons of soil per acre and 11 per cent of the rainfall. Thus we
see that erosion speeds up as the soil is whittled off, and that land planted to
cotton erodes 9 times faster than where it is planted to lespedeza, and at the
same time loses more water.
Erosion Speeds Up.
At the Arkansas-Louisiana-Texas Sandy Lands Erosion
Station, Tyler, Texas, in 1931, on Kirvin fine sandy loam having an 8-per cent
slope, 16.6 per cent of the rainfall was lost as runoff from land planted to
corn; from cotton the loss was 13.4 per cent; and from Bermuda sod, 2.5 per
cent. From deeply eroded areas, with the clay subsoil exposed, the average loss
by run-off from three cotton plots was 17.6 per cent of the rainfall. The
corresponding soil losses from the same plots were as follows, expressed in tons
per acre: 20.7 from corn land, 15.8 from cotton, and .5 from Bermuda sod. The
deeply eroded areas planted to cotton lost an average of 55 tons per acre, or
more than three times as much as was lost from the topsoil. Thus, it is seen
that on this soil both erosion and runoff are highest on land used for corn and
cotton, and that they are very low from grassland. The very much higher loss of
soil from the subsoil plots shows that erosion in this region speeds up as the
process continues.
Effect of Length of Slope.
At the Bethany, Missouri Erosion Station land
planted continuously to corn lost soil, in 1931, from a plot 146 feet long on an
8-per cent slope, at the rate of 104.71 tons per acre, along with 28.22 per cent
of the precipitation as runoff. One one-inch rain, on the 5th of June, caused a
soil loss from this plot at the rate of 19 1/2 tons per acre. The corresponding
runoff was 39.7 per cent of the precipitation. A 73-foot plot immediately
alongside of the 146-foot plot lost soil at the rate of 84.08 tons per acre,
with a corresponding runoff amounting to 30.10 per cent of the rainfall. The
rain of June 5 removed soil from the shorter plot at the rate of 15.7 tons per
acre, with a 49.5 per cent rainfall loss. In other words, length of slope here
considerably affects the rate of soil loss. At the Central Piedmont Station in
North Carolina the losses of soil from a 10-per cent slope were as follows: 14
tons per acre in an area 145 feet long; 12 tons from an area 72 1/2 feet long;
and 16 tons from an area 145 feet long. thus the loses do not conform on these
markedly different soils. (All these areas were protected, so that there was no
intake or loss of water above the catchment basins.)
Annual Soil Losses.
A few years ago, before we knew very much about the
enormity of the problem, it was estimated that erosion was washing out of the
fields and pastures of this country not less than 1,500,000,000 tons of soil
annually.3 This estimate astounded a good many people. Now, on the basis of
measurements at one of the recently established soil erosion experiment
stations, it is indicated that in 1930, which was about an average year from the
standpoint of seasonal condition, 16,534,800 acres of the rolling Red Plains
region of Texas and Oklahoma lost 440 million tons of soil. On the 10th of May,
1930, one 5-inch rain in the Black Belt of Texas washed off the rich black
topsoil from slopes of only 4 per cent at the rate of 23 tons per acre. This
rain, according to this measurement, took a toll of not less than 100 million
tons of soil from the sloping part of this famous cotton area. In other words,
when we get down to the task of quantitative measurements, we begin to see that
here is a problem whose destructive potency not only greatly exceeds all
previous ideas concerning it, but comes close to exceeding the possibilities of
human comprehension.
We have pointed fingers of warning toward China as a terrifying example of
wasted agricultural lands. The devastation in that old, old country has indeed
been appalling. Clearing the timber from the uplands and cultivating the
stripped slopes without any protection, the soil has washed away from millions
of acres of once productive fields; hideous gullies and even canyons have dug
deeply into the devastated areas. Hordes of human beings, leaving the
erosion-destroyed slopes of the Celestial Empire, have densely concentrated upon
the flat valley lands. There, every available foot of ground is used for cops.
Even the roots of crops are dug for fuel, and all organic refuse is scrupulously
saved for fertilizer. The older fields of the alluvial plains are fertilized
with fresh alluvial deposits collected in pits during periods of overflow. After
four thousand years of building levees and digging canals, the Yellow River of
China, which in that country is known as the "Scourge of the Sons of
Han," broke over its banks in 1877 to drown a million human beings. In 1852
this Titan, in mighty flood, changed its channel, sweeping northward to enter
the Yellow Sea 300 miles beyond its former mouth. This sea, a part of the
Pacific Ocean, derives its name from water colored yellow with the debris of
erosion, brought down from the still wasting slopes far up the valleys.
The plant food removed from the fields and pastures of America every year by
erosion greatly exceeds that removed by the crops harvested. That taken by crops
can be restored in the form of fertilizer, but that taken by erosion can not be
restored, because this malevolent process takes the whole body of the soil,
plant food and all. Land impoverished strictly by plant food depletion, as
sometimes results from continuos growing with the clean-tilled crops, is not
worn-out land; the only worn-out land that we have is that which has been so
badly washed that it would be entirely futile to undertake it reclamation.
Soil Depth.
Many people have the idea that the soil (as distinguished from
the subsoil) is much deeper than it really is. On examining 172 soil samples
collected from 34 states and representing, very largely, important upland types
it was found that the soil depth as recorded averaged only 9 inches. Many of our
most important types of farm land range from only about 3 to 7 inches in depth
of topsoil. From some of those we are losing this invaluable surface layer
within 10 to 40 or 50 years of cultivation, depending on the character of the
soil, the slope and the crops grown. When this layer is gone, the farmer's
principal capital is gone. The material below is too poor in countless instances
for profitable production, even when prices are good. We cannot build the
topsoil back after it is gone, nor can we haul it back into the fields. We can
increase the productivity of some eroded land, to be sure, by growing the
soil-improving crops, liming and fertilizing; but we cannot replace the soil
that nature put there. By terracing and growing grass we sometimes catch
material washing down from slopes above still retaining a covering of soil, but
that is not what I have reference to.
The Federal Land Bank of Houston, Texas, lends on the basis that the top six
inches of soil represents the farmer's principal capital. If the bank discovers
that a farmer who has been granted a loan is permitting his fields to wash at a
rate faster than six inches in thirty-five years on a thirty-five year loan,
foreclosure proceedings ensue. Very few foreclosures have been necessary,
however, because if the farmer does not know how to build terraces, the bank
sends out its soil-conservation expert and shows him how.
Erosion Surveys.
Some of you may have heard about the findings of the
Oklahoma soil erosion survey, completed in 1930. It is such a terrifying example
of unnecessary soil depletion that the results will bear repeating. Of
approximately 16 million acres in cultivation in that state, 13 million acres
were found to be suffering from severe erosion, 5,726,000 acres having reached
the stage of gullying. Of 1,694,000 acres abandoned in the State during the past
few years, 1,359,000 acres were abandoned because of erosion.
Two years ago the bureau of Chemistry and Soils made a general survey of
seventy counties lying in the Brazos River watershed of Texas, finding over one
large section within this watershed 88 per cent of all the cultivated area
either gullied or subject to wasteful sheet washing, the area thus affected
amounting to 6 million acres.
This sort of thing is to be found in numerous other localities, as in
northern Missouri, southern Iowa, southern Indiana and Ohio, southwestern
Wisconsin, Kentucky, Tennessee, parts of Kansas, Nebraska, California and other
states. In many of these regions even the topography of some localities has been
changed. Gullies have ribbed thousands of slopes than once were smooth and
rounded. Unproductive clay sticks out in countless places.
Effect of Soil Variability on Moisture.
Not only does soil character
enormously affect the rate and nature of erosion, but it markedly affects also
the moisture retentiveness of soil. For example, at the beginning of the season
May 13, 1931, virgin soil of the Vernon fine sandy loam at the Red Plains
Erosion Station in central Oklahoma, planted to cotton, contained approximately
the same amount of moisture as the desurfaced clay subsoil; i.e., 15.08 per cent
and 15.38 per cent, respectively; but at harvest time, September 1, the uneroded
soil contained 5.91 per cent of moisture, while the exposed clay contained 7.12
per cent. The fact that the virgin soil produced 162 pounds of cotton per acre,
as against 98 pounds for the eroded soil, shows that moisture consumption by the
much heavier vegetative growth on the virgin soil was much greater than on the
clay. Moreover, a smaller proportion of the moisture rigidly fixed in the
smaller interstices of the clay particles was available to the plants than of
that contained in the larger pore spaces of the fine sandy loam topsoil. In
other words, the moisture efficiency of a soil is, in a large measure, a
function of the structural efficiency of a soil. Structural efficiency depends
on a number of factors, such as texture, vegetable-matter content and structural
porosity.
In contrast to the moisture behavior on Vernon fine sandy loam, it is
interesting to observe the corresponding behavior on the soil and subsoil of the
Houston black clay in central Texas, in 1931, under similar conditions of
precipitation (very low rainfall). In this instance, the uneroded clay soil at
the beginning of the crop season (corn in this case), on April 10, contained
23.5 per cent of moisture, as against 16.8 per cent in the adjacent desurfaced,
humus-free chalky subsoil. The moisture in the normal soil continued to exceed
that in the exposed subsoil throughout the growing season, until about the time
the corn began to mature, when the moisture content of the normal soil dropped
below that of the subsoil, or to 13.8 per cent as against 15.9 per cent. The
fact that the uneroded soil produced seven times as much corn as the exposed
subsoil undoubtedly explains the reversal of the moisture situation toward the
end of the season, when the heavier growth called for a larger moisture supply.
Here, too, structural efficiency of the soil obviously plays an important role
with respect to moisture efficiency, but the process involved is somewhat
different from that in the case of the Vernon fine sandy loam.
Erosion Markedly Affects Vegetation.
The results of careful vegetation
surveys on equal areas of eroded and uneroded Houston black clay in central
Texas have shown extraordinary changes with respect to native flora,
transmutations due entirely to the effects of stripping off the topsoil. The
virgin grassland vegetation on uneroded soil, in one representative instance,
covered 94 per cent of the surface, and 93 per cent of the plants were grasses.
On severely eroded soil, originally of the same kind and occupying about the
same slope, which was cultivated and then abandoned, 60 per cent of the surface
was bare, and of the plants present only 1 per cent consisted of grasses, while
39 per cent consisted of woods.
Similar surveys in Oklahoma, Kansas, North Carolina and New Jersey have shown
in every instance much the same thing; namely, a complete upsetting of the
natural vegetative conditions by erosion. We see conspicuous examples of this
all over the eastern part of the country: pine forests, sassafras and persimmon
thickets, smilax vines, poverty grass and golden rod replacing magnificent
forests of hardwoods.
Man-Made Erosion.
The erosion that we have been emphasizing, as previously
stated, is of the man-induced kind, the abnormal kind, as distinguished from
normal or natural erosion, under which the removal of surface soil goes on
exceedingly slowly, due to the favorable conditions of ground stabilization,
such as is established and approximately maintained through the
instrumentalities of vegetative cover, the relatively high absorptive capacity
that goes with normally developed soil porosity and the restraining influences
of gentle slopes or angle of repose. Vegetation and soil porosity (such as
nature establishes), separately and collectively, exert a tremendous opposing
force to transportation of soil material by running water, slowing down surface
removal to a point where equilibrium between rate of erosion and soil building
from the parent materials beneath is almost, but not quite, established. Had
these counterbalancing natural processes attained equilibrium some eons ago, we
would not have throughout the world nearly so many valleys and glens and
canyons. We would have instead vastly more flat land of a poorly drained nature,
or what perhaps would be worse, enormous stretches of severely leached soil such
as are known as laterites.
Let's consider for a moment the powerful effect that the ground-cover of
forest leaves has upon soil absorption of rainfall. At the erosion station in
central Oklahoma the forest-litter was burned from a measured area of post
oak-black jack timber in the spring of 1930. Another area of the same size,
immediately alongside was left undisturbed. In May of that year, during a period
of almost continuous rainfall, the runoff from the unburned plot was at the rate
of 250 gallons per acre, while that from the burned plot was at the rate of
27,600 gallons per acre. The excess of runoff from the burned area over that
from the unburned area, plus the water-holding capacity of the leaf-litter
covering (16.7 tons per acre), was approximately 90 tons per acre. Thus, the
effectiveness of a thin cover of leaves as a protection to the soil is seen to
be far greater than the mere capacity of the leaf covering to absorb water. The
leaf cover obviously functions to send clear water down into the soil rather
than the muddy water that flows over unprotected burned areas, which latter
chokes up the pore spaces developed through natural processes of soil building
(as holes formed by decaying roots and by insects and worms, and the openings
that normally go with a mellow humus-charged soil).
And so, when we remove the trees, shrubs and grasses and plow up the ground
we lay bare the soil to the wrath of the elements. Erosion is vastly speeded up;
and we find that instead of being the "one immutable, unchangeable
permanent resource," it has been described, the soil is one of the most
destructive [destructible] of our great natural resources, save such things as
coal and petroleum whose utilization in the scheme of civilization calls for
their complete destruction by fire. The soil is not consumed as by burning, of
course; but when it is washed out of the fields it is destroyed, insofar as
having value for the farmer who has lost it. And again, as a matter of emphasis,
it should be remembered that soil can not be built back in the ordinary life of
a man. It can be improved by growing soil-building crops, by use of manure and
fertilizer and with the aid of terracing and strip-cropping, but it can not be
restored very easily, if at all, to the original condition established by
nature.
Deposition of Eroded Matter.
Beyond the washing of soil from sloping areas,
the products of erosion go to fill reservoirs, stream channels and to cover
fertile bottom lands with relatively infertile sand. Some of the deposits laid
down from stream overflows are beneficial, but often they are not because the
alluvial soils are already highly productive and need no additional sediments. A
bad feature of sedimentation is that sand is assorted from the waterborne
material and laid down over good soil or deposited in channels to make streams
more susceptible to overflow.
The Mississippi River carries into the Gulf of Mexico every year 418 million
tons of solid material, aside from enormous quantities of dissolved matter. The
streams from the Piedmont of South Carolina are doing precisely the same thing,
though on a smaller scale, of course. But this is not the full measure of the
evil of this traffic in farm land, by any manner of means. Very much more of the
material washed out of the fields every year is temporarily stranded en route to
tidewater; along lower slopes and in the channels and over the bottoms of every
river, creek, branch and drainageway.
The Nation's Most Priceless Asset.
Our soil is our most priceless asset, and
is likely to continue to be. Marvelous as have been the discoveries of
chemistry, it appears that there yet remains to be manufactured upon a purely
synthetic basis one single major food product. It is unsafe to make predictions
relating to future discoveries, but all evidence points to the probability of
the soil continuing to be the primary source of the principal food and raiment
of mankind. At any time the land may be called upon to produce largely increased
tonnages of commercial cellulose and even fuel for our internal-combustion
engines. It is, therefore, an economic necessity and a patriotic and moral
obligation to preserve this absolutely vital resource-this product that can not
be entirely be rebuilt within the ordinary span of an human life.
Better Land Utilization.
Some very extensive soils are inherently poor. These
are rapidly reduced to essential sterility by erosion. Other soils ranging from
fair to excellent in productivity are quickly reduced to a condition of poor
land if not protected against the wasting force of erosion. More and more we
must strive for the maintenance of the virgin fertility of our farm lands, or
that part of it still remaining as topsoil. Indeed, the necessity to conserve
the soil is acutely vital to the welfare of the state and nation. From now on
you are likely to hear more and more about better land utilization, the use of
the soil more in accordance with its natural crop adaptations and fitness for
cultivation, and the handling of it more in accordance with the peculiar needs
of a particular type of farming. Marginal and submarginal land, that is to say,
poor and very poor land, apparently have about had their day as crop-producing
land, for the while at any rate. While failing to provide an adequate living for
those operating on them, they have, nevertheless, in the aggregate contributed
largely to the stores of unsold crops. There are some instances where poor soils
can be farmed with fair success, but to a large extent such lands constitute a
millstone about the neck of those who farm them. Cheap production calls for good
land; the high-cost producer of crops is likely to be left too far outside the
limits of stable existence for comfort.
How Crop Yields Have Held Up.
Notwithstanding the vast continuing losses
caused by erosion, we are not on the verge of a land shortage. In spite of the
appalling wastage, we have recently been confronted with the anomalous situation
of having on our hands apparent large crop surpluses. Improved varieties of
crops, largely increased use of fertilizers and labor-saving machinery, and the
abandonment of worn-out land for land still retaining a part of the original
topsoil have contributed toward continuing big crops. These improvements speak
of progress, in one direction at any rate. They are not given for the asking,
however, Machinery does not minimize erosion, unless it is built and used for
that specific purpose. It may even cause the speeding up of the process. And it
should be remembered that notwithstanding the improvement of seed and cultural
methods, the improvement and increased use of farm machinery, the increased use
of fertilizers and soil-improving crops and the far-reaching assistance of
educational research and extension services, at large cost, our crop yields are
not all increasing. In numerous localities the yields have fallen. The average
yield of corn for the ten-year period 1871 to 1880, inclusive, was 27.04 bushels
per acre, as against 26.13 bushels for the ten-year period 1921 to 1930. The
highest and lowest annual yields for the first period were 30.8 and 20.7 bushels
per acre, respectively; the corresponding yields for the later period were 29.6
and 20.6 bushels per acre. Wheat yields increased from a ten-year average of
12.4 bushels per acre for the period of 1871 to 1880, inclusive, to 14.33
bushels for the period 1901 to 1910, inclusive; but for the last decade, 1921 to
1930, inclusive, the yield was 14.25 bushels. The average yield of cotton for
the ten-year period 1871 to 1880, inclusive, was 186.42 pounds per acre, as
against 152.96 pounds for the period 1921 to 1930, inclusive.4 In numerous
localities the yields of these crops have declined much more than these national
averages, even to the extent of causing much abandonment of land.
The Meaning of Conservation.
Finally the nation is coming to understand the
meaning of conservation. Our resources in land, timber, mineral products and
wild life were so vast in the beginning, that it was quite natural for us to
think of those things in terms of permanent abundance and inexhaustibility. It
was quite natural also for us to project the wasteful practices, such as always
characterize pioneer conditions, far out beyond the bounds of those primitive
times. For many decades conservation was considered a sort of euphonious term,
vaguely construed and patiently granted a fitting cloak for those harmless
humans who, according to the ideas of the average man and woman, were born to
look on the dark side of life.
We are slowly coming out of this hypnotic state of mind. We are beginning to
see that the spirit of "let it alone" and of imagined self-sufficiency
are erroneous conceptions with respect to land usage, and that stubbornly
following their lead can only take us into deeper difficulties. Many of us are
no longer inclined to look upon wasted hillsides of shallow soil and exposed
clay and gully-destroyed fields as an unavoidable act of nature. Now we are
seeing such things in their true inglorious meaning, the product of man's
wasteful methods. When we are told that the Grand Canyon of the Colorado had but
a trench thousands of feet deep before white man crossed the Atlantic, we
immediately answer: "Yes, and it probably took thousands of centuries for
the cutting." Just speculate for a moment as to what would have happened if
such mighty chasms had cut down at the rate gullies are now being formed in
countless fields, such, for example, as Providence Cave in southwestern Georgia,
a ravine which has been gouged out to a depth of 150 feet in fifty years, or a
75-foot gully near Ventura, California, from which beans were harvested in 1914.
Topography and General Extent of Erosion In South Carolina.
Having outlined
the behavior of erosion, its effects and extent from the national standpoint,
let's examine the situation as it relates specifically to South Carolina. The
Piedmont portion of the state will be emphasized because it is here that the
evil is most costly and extensive.
The Piedmont, together with a comparatively small segment of the Blue Ridge
Mountains, comprises about one-third of the state-the western part, or that part
lying above the fall line, marked roughly by a border zone through which the
waters of the Catawba, Broad, Saluda and Savannah rivers cascade to the lower
coastal plain region. This line crosses the state near Augusta, Columbia, Camden
and Cheraw. Thus, this upper country of the Piedmont and Blue Ridge Mountains
covers part of Aiken, Lexington, Richland, Kershaw and Chesterfield counties and
all of the 18 counties to the west of these.
The region is characteristically of rolling topography, with a range of
elevation from around 200 to 300 feet above sea level, along the fall line, to
around 900 to 1,000 or a little more along the line of contact with the Blue
Ridge. As viewed from a commanding position, the general upland level has the
character of a plain, with here and there isolated peaks of more resistant rocks
(generally quartzite) rising conspicuously above the dominant skyline (such as
the peaks of the Kings Mountain group). In detail this great area, although once
a true plain sloping gradually toward the sea, has been dissected by an
intricate system of rivers and lesser drainageways. Generally, there is a
difference in elevation from the crest of the inter-stream divides to the stream
bottoms below, ranging from about 50 to 200 or 250 feet. Parts of the region are
of relative smooth surface; some of the broader divides are flattish or of
table-land character. There are few places, nevertheless, without some slope. It
is probably safe to say that in the neighborhood of 85 to 90 per cent of the
uplands has a slope of 2 per cent or more. The average slope would run, perhaps
around 7 or 8 per cent, or a little more. There are countless slopes having
gradients in excess of 15 per cent (and, of course, many that are steeper in the
mountainous segment). Many of these steeper slopes are in cultivation or have
been sometime in the past. It might as well be stated now that, as I see it,
Piedmont slopes steeper than about 12 or 13 per cent generally should not be
used for plow crops. This is based on observation of countless examples of badly
eroded steep areas, and also on measured losses of soil at the erosion stations.
Certain gravelly and stony areas can be cultivated with a fair degree of safety
on somewhat steeper slopes, because of their greater stability. Of course, the
thick-growing, soil-holding crops, as grass and lespedeza, can be gown on most
any kind of slope; but these do not belong in the category of plow crops.
As a matter of emphasis, it might be said again that all sloping areas are
subject to erosion when used for the clean-tilled crops. I feel that it is safe
to estimate the proportion of south Carolina Piedmont upland subject to erosion,
when used for clean-tilled crops for any considerable length of time, as
represented by 85 to 90 per cent of the area involved. On the smoother lands the
losses take place comparatively slowly, as a matter of course; but they take
place, nevertheless, and eventually impair the soil. Erosion begins quite
actively within 1 to 3 or 4 years after clearing off the virgin hardwoods on the
steeper lands; it begins at once, ordinarily, on reclearing those more sloping
areas that formerly were cultivated, and then abandoned and allowed to restock
with second-growth pine. It is probably safe to estimate that at least 70 per
cent of all the cultivated upland of the Piedmont portion of the state, together
with that formerly cultivated and now grown over with pine, has, in the course
of time, lost from 4 to 18 inches of soil and subsoil, with countless places
where the washing has cut away all the soil and subsoil, on down to soft
decomposed rock, or even down to hard bedrock. This loss means more when we come
to understand that the average depth of topsoil in the region is not more than
about 8 or 9 inches, and that the better part of this surface layer, the part so
richly charged with humus, is seldom deeper than about 4 inches.
Piedmont Soils.
A word about the soils of the region: As to types, the soils
of the Piedmont of South Carolina are not very numerous; but the variation among
these types is decidedly intensive in many places, especially on those slopes
where erosion has cut through the top layer of small and large areas, down into
the upper subsoil, and, after that, on down into the lower subsoil, finally to
the depth of soft, decayed rock, from which these soils have been formed by
nature's lengthy process of building. Thus, we find numerous hillsides spotted
gray, red and yellow, according to the progress of erosion, and also according
to the complexity of the virgin soil.
The principal soils are those of the brittle red clay subsoil group,
designated as the Cecil series. These have been derived from granite and related
rocks, first through decay of the basal rock and then the building of this
material into soil by ages of freezing, thawing, the action of percolating
rainwater and the effects of vegetation, microorganisms, earthworms and
burrowing insects and animals. The most extensive types are the Cecil sandy clay
loam, Cecil clay loam and Cecil sandy loam. Other important groups are the
Appling, Wilkes, Georgeville, Alamance and Iredell. These are all fully
described in the various county soil survey reports, so that time need not be
taken to discuss them here. These reports not only describe the soils but show
their extent and location and give their crop adaptations and better methods of
use. The names and areas of the different types found in Spartanburg County may
be cited as an example:
Cecil sandy clay loam |
209,152 |
Cecil sandy loam |
168,832 |
Cecil clay loam |
66,688 |
Cecil gravelly sandy clay loam |
11,392 |
Cecil gravelly sandy loam |
5,696 |
Cecil coarse sandy loam |
2,688 |
Cecil fine sandy loam |
2,304 |
Meadow |
23,488 |
Appling sandy loam |
9,216 |
Iredell fine sandy loam |
6,784 |
Iredell loam |
896 |
Louisa sandy clay loam |
5,184 |
Louisa clay loam |
4,800 |
Congaree silt loam |
3,008 |
Congaree fine sandy loam |
768 |
Davidson clay loam |
1,728 |
Durham sandy loam |
1,280 |
Porters loam |
250 |
Total |
524,162 |
Examples of Erosion In South Carolina.
As examples of the severest phase of
erosion, that is, gullying plus deep sheet erosion, we will probably find the
greatest areas in a strip crossing the state through Lancaster, Fairfield and
Union counties. As long ago as 1912 a soil survey of Fairfield County showed on
the soil map 90,560 acres of land, practically all of which had been tilled at
one time or another since the settlement of the country, under the
classification Rough gullied land. This was once good land, but the greater part
of it had been deeply dissected with gullies, and between the gullies most of
the soil, and in countless places even the subsoil, had been washed off at that
time. There were scattered areas of still cultivable land between the gullies
and along some of the crests of the broader ridges; but such areas were
isolated, so that the soil surveyors considered that they properly belonged
under the general classification mentioned above. By far the greater part of
this area really represented land which had been destroyed, at least in the
sense of having further value for crop production by the ordinary farm methods.
Indeed, much of the land was so badly cut to pieces that major engineering
operations would have been necessary to restore it to a reasonable state of
arability.
The 90,000 acres referred to, however, did not fully cover the extent of
erosion in the county. There were numerous other eroded areas included with the
better soil types, as shown on the map. Beyond that, 46,650 acres of
stream-bottom land were mapped as meadow, which represents land of a swampy or
semi-swampy nature, having for the greater part little value except for grazing
and the growing of trees. These bottom lands, nevertheless, once were considered
the richest of the county.
The work of this survey came under my supervision as a representative of the
Department of Agriculture, by which it was made. After a lapse of twenty years I
went back into this county, this year, to have another look at the situation-to
see what had taken place since the survey was made. There were three roads which
formerly I had driven over quite comfortably with horse and buggy. Again I tried
these roads in an automobile, last September, but was forced to turn back in
every instance. The roads had grown into canyons; trees were growing up and down
them in many places. (It is a fortunate thing that nature provided the pine tree
for land of this kind, since man insists on creating such conditions. At any
rate, the greater part of it is being reforested by natural processes.)
Amidst a maze of ravines I followed another winding road and finally reached
an old farmstead. Here a magnificent old mansion was tumbling to ruin. From
about its foundations 3 feet of soil have washed away. Of 1,004 acres comprised
in this erstwhile farm, not one field remains in cultivation, although
practically the entire area once was farmed. I went around over this farm and
found not so much as a single acre in one place which seemed to me as worth
plowing. The soil washed away long ago, and after that most of the subsoil. Rock
was exposed in thousands of places-hard rock and soft rotten rock. Gullies
streaked the land in all directions, not only here but through all the
surrounding country. I saw the farm burial place on a knoll about one-eighth of
a mile from the disintegrating mansion. I walked over to this. It was more of a
process of sliding down and crawling out of the intervening gullies. It took
over 30 minutes to get there. Samples taken from various places, including one
diminutive patch of the original hardwoods, show that the soil has suffered
terribly. The humus of the skeleton soils now to be found is too deficient for
any chance of good yields. Recovery of such parts of the land as still might be
plowed would entail expensive terracing, growing of humus-supplying crops and
addition of fertilizers. The land is now best suited to timber, and pine trees
are taking it in charge.
After going over many parts of the county and checking the soil map made
twenty years ago, it was estimated that the area of essentially destroyed land
has increased something like 20 per cent, or at the rate of nearly 1,800 acres a
year.
Now let me add here that there still remains much good land in Fairfield
County, smooth land, good for crops. I am referring merely to the worst part of
the land, and in fairness let me say that there are other counties in other
states, both north and south, which contain even a larger proportion of worn-out
land. I have in mind a county where a soil survey has just been completed which
shows 190,000 acres of formerly cropped land that has been ruined by erosion,
and still another with 200,000 acres. As I see it, nothing is to be gained by
covering up those facts. We must bring them out in the open as a stimulus to
greater efforts at soil conservation.
Extensive Sheet Erosion.
In another county, Spartanburg County, a soil survey
has classed 297,216 acres as clay loam, sandy clay loam and gravelly sand clay
loam. Examination of the soil in remnants of virgin stands of mixed hardwoods
and pine shows the original soil to consist of some 4 to 8 inches of brownish or
yellowish, mellow sandy loam and loam. This top layer is gone or largely gone
from 297,000 acres. These clay loams are in a sense new soils, representing
products of the excessive erosion which has taken place over the cultivated
slopes. They are not worthless soils, by any means, for the fortunate reason
that the upper subsoil of the great majority of the Piedmont country is still
fairly good land, where duly fertilized and properly terraced and rotated so as
to prevent washing from extending down into the deeper, less productive subsoil.
There are many good terraces in Spartanburg County, and with good farming these
lands will last yet a long time. Nevertheless, soil-denuded fields are not so
productive as were the fields with the original soil, and they are not so easily
tilled. They bake more in dry weather, and corn suffers very much more than it
would on the original loam and sandy loam topsoil. This fact is attested by the
generally poor crop of this year throughout the Piedmont from Washington, D.C.,
to east-central Alabama. With few exceptions, land eroded down to clay has
produced in this region, this year (a dry year following a wet spring),
exceedingly poor corn. On smooth, uneroded land, however, there is in the same
region a fair crop of corn. Under certain conditions, cotton also suffers more
on these erosion-produced lands.
It should be observed that Spartanburg County has, also, some measure of land
where the process of despoliation by erosion has advanced to the point of
danger. There are, for example, 209,152 acres of Cecil sandy clay loam in the
county. Most of the original forest was removed from this long ago. Now about 60
per cent of the land is under cultivation, the remainder being largely covered
with old field pine. Now when we critically examine these old-field-pine areas
we find many of them contain gullied or deeply eroded soil where ordinary farm
crops are not likely to give a very satisfactory living to those who undertake
its cultivation.
These two conditions of sheet erosion and gullying are to be found throughout
this great Piedmont country. They are present in every county, indeed in every
township, all across the belt from Alabama to within sight of New York City.
Much of the abandoned land in the Carolinas and southward was terraced long ago.
While the terraces did much good, undoubtedly, I am convinced that many of them
were not built in just the right way. At any rate, erosion has gone ahead too
aggressively, and probably not less than 500,000 acres of land in upper South
Carolina, alone, have reached a stage of worthlessness, or an approximation of
that, insofar as safe use for farm crops is concerned. Its best use now is for
the growing of trees and grazing.
The appearance of the Piedmont country has changed vastly since the coming of
white man with his axes and plows. This change was described in a very
interesting manner 30 years ago by Mr. F.W. Taylor and Thomas D. Rice, in the
soil survey of the Abbeville Area, South Carolina. They had the following to say
about this country around Abbeville, which is representative of a considerable
part of the Piedmont section of the state:
"The original forest growth was quite different from the forests of the
present time. On the highlands the oak, hickory and chestnut were of large
growth and stood far apart. There was no underbrush and the woods were carpeted
with grass and the wild pea vine. Along the streams and in the valleys the
distinctive growth was willow, beech, birch, black walnut, ash, poplar and gum.
The cane also flourished best here, although it often grew upon the higher
ground. The cane growth was the standard by which the early settlers estimated
the value of the land. If it grew only to the height of a man's head, the land
was esteemed ordinary, while a growth of from 20 to 30 feet indicated the
highest fertility. Not only the forests, but the cultivated fields as well,
present a very different aspect now from what they did after the country was
first opened up. It was then new and beautiful and as remarkable for the
luxuriant richness of its landscape as it is now for the striking features of
its rolling hills and long, narrow valleys. The original forest has disappeared
almost entirely, and has been replaced by scrubby oaks, by underbrush, and by
short leaf pines of the abandoned fields. The chestnut and chestnut oaks have
been dying out for the past sixty years, and the cane likewise almost
disappeared."
Deposition of Erosion Products.
We have discussed erosion in the uplands.
What has happened to the bottom lands? Already it has been pointed out that the
products of soil erosion are distributed from the point of origin all along the
journey to tidewater. More than half of the area of the stream bottom land in
the Piedmont plateau, not only in South Carolina but for the entire area of 50
million acres, has been buried with sand and mud to depths ranging from a few
inches to six feet or more, since the agricultural occupation of the region.
Much of this has been classed as meadow in the soil surveys made throughout this
great region: a semi-swampy type of land, usually covered with willow, alder,
sweet gum, smilax, blackberry and rushes. Of 269,440 acres of alluvial mapped in
the stream bottoms of the South Carolina Piedmont, 210,752 acres, or 72 per cent
of the total area, has been classed as meadow. W.E. McLendon (a graduate of
Clemson College) in the report published in connection with the soil survey of
Anderson County, South Carolina, has the following to say of this type of land:
"Some areas were originally a good loam, but have since been covered
with loose sand, rendering them almost worthless. Others are quite sandy beneath
and loamy on top. The creek bottoms vary more widely still. The original soil
was for the most part a brownish or black sandy loam to loam, but the floods of
recent years have covered the older soil in many places with loose sand. Now in
these areas there is a mixture of loamy and sandy spots, even in very small
areas. Generally the narrower bottoms are the sandiest and most subject to
changes with every overflow. In the earlier settlement of the section the bottom
lands were highly prized for the production of corn and forage crops. Then
overflows were not very frequent and rarely destroyed the crops; but as more and
more of the uplands were cleared floods became correspondingly more frequent and
disastrous, until now the cultivation of the bottom lands is considered very
risky. Large quantities of sand have been washed in from adjacent slopes, badly
obstructing the streams and rendering the soil of little value."
Part II
The National Program of Soil and Water Conservation
It should be clear from what has been said that we have not made very much
progress in this country with respect to the problem of erosion control. Rather,
the farmers over the greater part of the country have been pretty soundly asleep
about the seriousness of this process of land impairment and absolute land
destruction. Generally, too, they not only have done little or nothing in
opposition to continuing soil impoverishment by this process, which of all the
combinations of soil-impoverishing agencies having to do with the human factor
is by far the most serious; but many of them have not even recognized the most
menacing aspect of the problem: the effects of sheet erosion. Moreover, there
has been actual encouragement of erosion through such unwise practices as the
running of rows up-and-down the slopes and the continuous growing of
clean-tilled, humus-exhausting crops. Not only this, but until recently nothing
was done in the way of persistent experimental effort to determine the most
effective methods of control, not to mention the working out of the basic
principles of erosion processes or the measuring of the losses. In practically
every other field of agricultural endeavor an enormous amount of research work
has been done. We have experiment stations in every state, and numerous
substations on major types of farm land, and still more experiments in outlying
fields. A very considerable part of this work has related to increasing crop
yields and the maintenance of soil-fertility through the use of fertilizers,
soil-improving crops, manures, crop rotations, better tillage methods and so on.
All of this work, indispensable as it is, has no intentional specific bearing
upon prevention of soil decline by erosion. This most impoverishing of all
agencies affecting the soil, an agency that rapidly steals the whole body of the
soil, plant food and all, has been left out of the efforts of mankind in the
interest of better land use almost as if it represented something untouchable.
Recognizing the acute need for better knowledge of erosion processes and
better methods for erosion control, a national program of soil and water
conservation was inaugurated about three years ago, following a survey of the
erosion situation in the country, which was carried out by myself. Now we have
eleven erosion experiment stations in as many major soil and climatic regions,
where through the cooperation of the states and the Federal Department of
Agriculture this problem is being vigorously attacked. The nearest one of these
to South Carolina is the Central Piedmont Station, 10 miles west of Statesville,
N.C., on Highway No. 10.
At these stations it is proposed to try out at the earliest possible moment
every promising practical method of slowing down erosion, in addition to
measuring the losses of soil, soil fertility and rainwater from different slopes
undergoing various cropping and tillage practices. The matter of terracing, as
previously stated, will be discussed by members of the technical staff of the
Bureau of Agricultural Engineering. I am going to attempt to point out some of
the most promising means for control through the instrumentality of soil-saving
crops and special soil treatment, based on present findings and indications at
these youthful experiment stations.
Strip Cropping.
Strip cropping represents a rather simple method of planting
along the natural contours of the land thick-growing, soil-saving crops like
sorghum, small grain, clover, lespedeza, velvet beans, grass and sweet potatoes,
in strips between clean-tilled crops, such as corn, cotton and Irish potatoes.
The purpose of the thick-growing crops, occupying positions corresponding to
those of locating terraces, is to slow down the rate of water flowing across the
field, thus to cause a part or all of the water-borne soil to be deposited. Now
this is almost precisely what happens with terracing. The terrace catches the
flowing water, slows down its rate of flow and causes the deposition of part of
its suspended load of rich soil material, slowly passing the excess water off to
the sides of the field. The strip crops retard the rate of running water and
spread the water out over the protected parts of the field so as to save the
soil and to cause more of the water to be absorbed by the ground.
Our experiments with this system of cropping have proved highly encouraging
since the very beginning. In the great cotton-producing Black Belt of central
Texas there has been no appreciable erosion from strip-cropped areas for a
period of 20 months, and there was practically none this year at the Red Plains
Station in central Oklahoma. The experiments with this system on the Cecil soil
at the Central Piedmont Station in North Carolina have been similarly
encouraging this year, the first year of installation. Strip cropping is so
practical, so cheap and so easy to apply that we are convinced it is going to be
extensively used in many parts of the country. Its most promising use is on the
gentler slopes. We feel, according to results thus far obtained, that where the
slope is greater than about 5 to 6 or 7 per cent, depending on the soil, the
character of rainfall and the crops grown, the system may need the support of
terracing. On a farm of 6,000 acres in the Texas Black Belt, where every field
is now under strip cropping, it has been found that where terraces are needed it
is not a very difficult matter to induce tenant farmers to build them. The very
fact that there is need for this type of cropping appears to affect the
psychology of a farmer to the extent of causing him to begin to think more about
the benefits to be gained from giving the land some sort of protection against
erosional wastage. This stimulus, further aided by the fact that the strips are
laid out just as terraces are and need no additional surveying for the
subsequent location of a terrace, is pushing along soil conservation methods in
parts of the Black Belt of Texas faster, I believe, than any other method we
have presented to the farmers of that region.
Probably the strips of the thick-growing crops should be planted broadcast in
the Piedmont country, rather than in rows. I observed this summer a considerable
number of fields in the South Carolina and Georgia Piedmont which are being
treated in this manner. Whether the strips were consciously planted for the
purpose of slowing down erosion or not was not determined, but they were there
and there is no question but that they will improve the situation in the fields
thus handled. The thick-growing crops that I saw were cowpeas and sorghum mixed,
and sweet potatoes. If, after the sorghum mixture is cut for hay, the stubble is
left during the winter and early spring, this stubble will probably control the
situation quite effectively until next planting time. The strips can be made as
wide as one chooses. The wider they are the more nearly complete will be the
control. We have found that where the contour of the land is such that the width
of the clean-tilled crops between the thick-growing crops varies, the matter of
having short rows can generally be avoided, if deemed desirable, by varying the
width of the thick-growing crops rather than that of the clean-tilled crops.
(Strip cropping is discussed in Leaflet No. 85, U.S. Department of Agriculture,
copies of which can be had on application.)
Strip Subsoiling.
We are testing out the efficacy of strip subsoiling, but
thus far have not obtained very promising results. This system, nevertheless, is
used in certain parts of the bean-growing districts of California with good
results. It simply consists of subsoiling the land to 18 or 20 inches along the
contours, over strips varying in width from one to several rows, and leaving
below this strip an unsubsoiled strip of equal or greater width. This develops a
sort of subterranean terrace, but we are not prepared to recommend its use as
yet.
Cover Crops.
No argument is necessary to convince any thinking person that it
is much better to keep the land covered with some form of vegetation throughout
the year than to leave it bare, especially in the more southerly regions where
the ground is seldom protected with a blanket of snow. Fields plowed in the fall
and left bare for next year's cotton or corn planting are certainly going to
wash to some extent during the winter, and they are even more likely to wash
with spring rains, if such rains come before planting time, as they so
frequently do. Erosion being most destructive during the summer season, the same
thing applies with even greater emphasis in relation to summer treatment of the
land. We have learned that any kind of vegetation on the land is better than no
kind. Our measured losses at the erosion stations show that soil moves off bare
slopes much faster than under any other condition. The rate of soil loss at
Statesville, North Carolina, from bare ground was, as already stated, 65 tons
per acre as against 17 tons where cotton was grown and only 11/2 tons where
lespedeza was grown. A winter cover of grain, whether of oats, barley or wheat,
is mighty good insurance against depreciation of the land by erosion; moreover,
a good crop of wheat or oats is a mighty useful thing to have about the average
Piedmont farm. We are testing out every legume that we can get hold of, both the
winter and summer types, for the purpose of working them more and more into our
cropping systems. Thus far lespedeza looks to be one of the best legumes for
this region, but cowpeas are still a mighty good crop and so are velvet bean.
Soybeans have in some parts of the country a reputation for being not especially
effective as an erosion-control crop, but our studies indicate that this is more
likely to be true where the crop is grown in rows or is drilled up-and-down the
slopes, whereas it is not particularly true where the crop is thickly sown
across the slopes.
We have had much to say about soil losses from erosion and nothing to say
about soil losses from leaching. The best information available is that
rainwater soaking down through the ground carries away by this process of
leaching very little of the phosphorous content of the soil and not so much of
the potash but the process does remove considerable lime and nitrate nitrogen.
Here again cover crops come into the picture. The roots going down into the soil
undoubtedly gather in and hold a considerable part of those soluble materials
which otherwise would leach down into the substrata. Part of this retained plant
food will pass up into the leaves of the plant to be incorporated with the soil
wherever the cover crop is plowed under. The plowing under of cover crops, or of
any other kind of humus-supplying material, for that matter, is decidedly
helpful in slowing down erosion. Every test we have made shows this. The saving
is remarkably high in many instances. Take the matter of manuring: Way up in the
Corn Belt of southwestern Iowa we found that two rains in August this year
washed 11-1/2 tons of soil per acre from unmanured land as against only 4-1/2
tons per acre from land immediately alongside, to which 8 tons of manure had
been added. These decaying vegetable materials act within the soil after the
manner of a sponge, making them more absorptive and keeping the pore spaces open
so that rainwater can better penetrate to desirable depths.
Crop Rotations.
All of our experiments have confirmed the soundness of old
ideas on the value of crop rotations. This is one of the methods that nature
uses in the prevention of the levelling down of the earth's surface to the
condition of marsh land. If lightning strikes a timbered area in the dry season
and sets fire to the woods, causing the timber to be burned off, the thing that
happens in most parts of the country with the very next growing season is the
appearance of a robust crop of weeds, grasses and shrubs. In the Piedmont, out
of this preliminary growth which affords a partial protection to the land pine
trees spring up and soon establish a good stand of second growth forest. This
gives still more protection. Gradually, from this stage of nature's rotation, we
see another move ahead, the appearance of hardwoods. Eventually a climax
vegetation is reestablished, this consisting of a growth like the original mixed
hardwoods and pine forest found in remaining patches here and there throughout
the Piedmont region The practice of crop rotations is commendable from every
angle of consideration. Nature endorses it, and nature is a pretty good planner
of affairs. Even if the rotation serves no other purpose than to increase the
organic supply of the soil and to protect the land from excessive loss of
moisture, it serves well.
Strip cropping, I believe, is going to encourage the practice of crop
rotations. Some farmers will begin with this method by putting in narrow strips
of the thick, soil-saving crops, with broad strips left for cotton or corn. This
may lead on, I believe it will lead on, to the seeding of broader and broader
strips of the thick-growing crops, eventually to give an equal area to the two
types of crops. By shifting the position of these occasionally or from year to
year, we will have a true rotation, and I am pretty sure we will have, also,
satisfactory control of erosion, or a situation very close to that, for the
gently sloping lands at least.
There is no need to discuss crop rotations further. We all know what the
practice means. We all know that legumes improve the fertility of the soil,
restoring in some measures at least one of the important elements of fertility,
nitrogen, which is stolen from the land by erosion, by the crops removed and by
the never-ending process of leaching.
Soil Manipulation.
At our Kansas Erosion Experiment Station we have developed
a hole digging cultivator, with shovel plows attached in such a manner that they
scoop out thousands of holes in the field, piling the dirt along the side of the
holes. Each hole then becomes a reservoir for holding rainwater on the land
until it sinks into the ground. This machine was developed for use on grain
land, especially on fallow land (where summer plowing is practiced in order to
conserve more of the rainfall by keeping the weeds killed off). Operating like
any ordinary cultivator, this implement digs 10,000 holes per acre. Under
ordinary moisture conditions 3 gallons of water are absorbed by each of the
holes before they begin to fill up, and then 2 more gallons are required to fill
them. Thus, with our first machines we are saving 50,000 gallons of rainwater
per acre. At the same time erosion is checked, not only to the extent of this
ground disposal of 50,000 gallons of rain per acre, but with slowing down the
runoff from the heavier rains by causing the flowing water to zigzag from one
hold to another. Out in Kansas where the land was scarified with this machine
the loss of rainwater from fallow land, at the time of the last tabulation of
results obtained, had amounted to only 1-1/2 per cent of the total precipitation
as against a loss of 34 per cent from untreated land immediately adjacent which
had been handled according to prevailing practice in the region. This winter the
man who made the machine is going to undertake to develop it for use with any
kind of crop. It has already worked satisfactorily in wheat fields and I believe
it is going to be a serviceable implement in the cultivation of corn and cotton.
At any rate, we are not going to permit it to stand as merely a saver of soil
and water in the less humid parts of the country, if our best efforts at further
development prove of avail.
Gully Control.
In connection with gully control let me say at once that the
time to stop a gully is during its infancy, before it has grown into a ravine or
canyon. Quite simple methods will go a long ways in the direction of control if
this course is followed. We are having almost 100 per cent success with the new
type of gully control which we effect with grass dams. With this simple,
inexpensive method we have almost completely effaced numerous gullies from large
fields and are now getting even better crops where the gullies formerly gnawed
at the heart of fields than from other parts of the fields.
The method is as follows: Fill old fertilizer sacks or any other kind of
sacks, no matter how rotten they may be so long as they half-way hold together,
with grass roots and soil or with soil and grass seed (probably Bermuda grass
would be the most effective for this region) and place these across the washes.
In the smaller gullies there will be many places where one of these sacks will
fill the bill, but usually at least three sacks are needed, and in some
instances more than this. A cardinal principle to be observed in all instances
is that the sack in the center of the gully shall be so placed as to lie lower
than those placed along the slopes of the wash. If this is not done, the water
will not concentrate toward the center; it will certainly wash around the ends.
I might say that this precaution applies to every other type of dam except those
that have overpasses for disposing of the impounded water when it reaches the
top of the dam. No matter whether you build a brush dam or a stone dam or an
earth dam, or a grass dam, be sure above all else to have the center lower than
the sides, after the manner of a V.
The grass grows right through the rotting bags, takes hold of the ground and
quickly establishes a stabilized soil condition in that part of the wash. The
plan calls for a succession of these dams up-and-down the wash, as is clearly
shown in our Leaflet No. 82 (Controlling Small Gullies by Bluegrass Sod).
We are also having splendid results with gully control, where the gullies are
larger than those which can be effectively stopped with grass dams, small brush,
stone or wire dams, by planting willows in the moist bottoms of the ravine,
straight across, and then black locust up-and-down the sides. Plant the willows
across the bottom in strips about 3 to 10 feet wide, in the spring at about
budding time. There will be little trouble in getting a start if there is any
moisture in the bottom of the gully. If not, some sort of small temporary rock
dam or brush dam should be installed to collect a moderate amount of soil. The
soil will contain moisture and in it willows can be grown effectively. Of
course, untimely freshets may, and probably will, wash out some of these
plantings, during their infancy especially; but when we come to fighting erosion
we must have perseverance if we are to get results. We must maintain terraces if
we get results from them; we must repair our houses, bridges and highways if we
get best results from them. Indeed, we must keep eternally on guard and on the
move if we are to make the most of our lives, including the preservation of our
sloping fields.
We are finding on certain soils that black locust grew very rapidly, so
rapidly indeed that we are counting on their producing tow fence posts per tree
in a period of 10 years, in northern Missouri. Our experiments at the
Statesville Station indicate that we can get good results with black locusts in
this country, although the trees may not grow quite so rapidly as in some of the
other parts of the country. We do not know about this as yet. They are one of
the few plants we have been able to get started on deeply eroded Cecil soil,
that is soil where, over considerable areas, not a living sprig of vegetation
was growing.
We are even plowing down the sides of gullies and planting these to locusts,
and with the aid of willow trees planted in the bottom of the ravine we are
rapidly building up dams, and this at almost no cost, beyond the time spent on
the job. Locust seed can be procured from the forestry departments, and from
these an abundant supply of seedlings can be quickly obtained for transplanting.
In connection with gully control, I see little hope of taking charge of such
ravines as I ran across in southwestern Georgia this past September. Down there
I came to a place where 37,000 acres of formerly tilled land, representing the
best type of land in southern Georgia, had been surveyed out as land destroyed
by gullying. I think nowhere in the world could a larger man-induced gully be
found than one of these. It was 150 feet deep. I talked with a man who went to
school in a schoolhouse that once stood in the center of this canyon. If it were
there now it would be suspended in the air. The schoolhouse toppled into this
yawning gully long ago, and with it has gone the barn from which the water ran
that started the gully. A tenant house and a graveyard with 50 graves have
tumbled into the chasm also. These buildings and the remains of mortal man have
joined the soil debris of 37,000 acres of destroyed farm land on its journey to
the caverns of the Gulf of Mexico.
The only possible practical way, probably, to put such gullies under control
would be to build diversion dams or terraces about their heads so as to pass the
water off in other directions, keep it out of the gully. This has been done in
the very region referred to. These are vertical-walled gullies, the kind that
grow by the washing out of the looser material of the substrata, to be followed
by tumbling in of the soil from above. Most of the gullies in the Piedmont
country are more or less V-shaped, and these are much easier controlled than the
straight-wall, undercutting type of gully, such as we do find in parts of the
Piedmont-in those parts where the substrata consist of soft rotten rock. Such
gullies call for special treatment, and I suspect this treatment will call for
diversion terraces, especially where the ravines have grown to any considerable
size.
Honeysuckle is another excellent crop for gully control. This will not grow
satisfactorily on raw clay which hardens and loses its moisture in summer, but
it can be started in the same way suggested for willow dams.
Use of Steep Land.
It has already been suggested that we should not use our
steeper slopes for clean-tilled crops. If we can not get them into grass, the
chances are that nature will take charge of the situation and plant them in pine
trees, here in the Piedmont, especially if we keep the fires out while they are
young in order to give them a chance. Now these trees are not going to be
harvested next year. But they may be harvested as a profitable crop if we live
long enough, or our children may take care of the harvesting. In the meantime,
they cover up ugly spots on a farm, make an eroded farmstead more habitable and
contribute to the general good of the region by keeping soil out of the streams
and reservoirs. I saw last summer while in this state a large reservoir, built
for the operation of a large cotton mill, which had completely filled up with
sand and mud, swept down from the uplands. This process is going on all through
the Piedmont region. In all probability the only way that the process of silting
of reservoirs can be stopped or materially slowed down will be to quite
cultivating the steeper slopes and to get them into trees or grass. In addition
to that it is going to be vitally necessary to give better protection to the
slopes that we do cultivate. We have an abundance of land still left in this
country. There is no necessity for cultivating so much steep areas. The teachers
of the country, if they will, can do much toward the encouragement of better
land utilization by driving home to the farmers of the regions they serve the
thought that in fighting erosion we are opposing the most powerful agency that
nature employs in carving out the valleys of the world. Erosion is more powerful
in modifying the surface of the earth than earthquakes, volcanoes, tidal waves
and all the excavations of mankind since the beginning of history The job of
controlling this prodigious implement is going to be difficult enough on our
smoother lands. The problem is simply hopeless on the steeper lands except
through vegetative means. We must resort to trees, to grass, to all forms of
vegetation in this phase of the fight.
Other Lines of Investigation.
It is not necessary to go into further detail
with respect to the investigational and demonstrational side of erosion control.
We are doing many other things. We are measuring the effects of waste farm and
woodland materials in reducing soil losses, such as rotted wheat straw, leaves
and pine needles; we are measuring the possibilities of renewing the
productivity of land made poor by erosion and the time and cost involved, even
though the main point of the national program is to conserve the soil yet
remaining rather than reclaim land already ruined.
The educational side of the program we consider to be a matter of major
importance. We must depend on people like you to a very large degree for help in
this direction. You will see the absolute necessity for this and your obligation
to assist in bringing the users of land out of their apathetic point of view
toward this pathetic problem. You do not need to be told, I am sure, that the
soil is a very sacred thing, a resource that was not given us to waste. You will
give of your knowledge, and freely of your advice, to those whom the
preservation of this most indispensable asset, this asset that belongs as much
to posterity as to ourselves, has been entrusted.
- Address delivered in connection with the South Carolina Teacher-training
program by H.H. Bennett, Chief, In Charge Soil Erosion Investigations, Bureau of
Chemistry and Soils, U.S. Department of Agriculture, at Spartanburg and Clemson
College, November 4, 1932; Columbia and Rock Hill, November 5, 1932.
- W.W Weir: Soil Erosion in California: Its Prevention and Control. Bul.
538, University of California, College of Agriculture, 1932.
- Soil Erosion a National Menace. Circular 33, U.S. Dept. of Agriculture,
(1928), page 5, Bennett, H.H. and Chapline, W.R.
- The statistical data relating to corn, wheat and cotton are from The
Yearbook, U.S. Dept. of Agriculture, for 1900, 1925 and 1930; Crops and Markets,
U.S. Dept. of Agriculture, Vol. 7, No. 12; and by memoranda from the Division of
Crop and Livestock Estimates, Bureau of Agricultural Economics.
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