The Record of Our Own Land
But now let us read the record of our own land in a short period of 300 years. In
the past 150 years, our occupation of this fabulous land has coincided with the coming of
the age of science and power-driven machines.
Along the Atlantic coast in the Piedmont we find charming landscapes of fields with red
soils and glowing grain fields. But in their midst we find an insidious enemy devouring
the land--stealing it away, ere we are aware, by sheet erosion, rain by rain, washing it
down into the streams and out to the sea. Sheet erosion, marked by shallow but numberless
rills in our fields, is blotted out by each plowing.
We forget what is happening to the good earth until we measure these soil and water
losses. More than 300 million acres out of our 400-odd million acres of farm fields are
now eroding faster than soil is being formed. That means destruction the land if erosion
is not controlled.
We are not guessing. Erosion experiment stations located throughout the country have
given us accurate answers. Let us compare rates of erosion under different conditions of
land coverage and use. Measurements through 5 years at the Statesville, N. C., erosion
experiment station show that, on an 8-percent slope, land in fallow without cropping lost
each year an average of 29 percent of rainfall in immediate runoff and 64 tons of soil per
acre in wash-off of soil.
This means that in 18 years, 7 inches of soil (the average depth of topsoil) would be
washed away. Under continuous cropping to cotton, as was once the general practice in this
region, the land lost each year an average of 10 percent of rainfall and 22 tons of soil
per acre per year.
At this rate it would take 44 years to erode away 7 inches of soil. Rotations reduced,
but did not stop erosion for the land lost 9 percent of the rain and enough soil so that
it would take 109 years to erode away 7 inches of soil. That is a very short time in the
life of our Nation. But where the land was kept in grass, it lost less than 1 percent of
rain and so little soil that it would take 96,000 years to wash away 7 inches of soil.
This rate is certainly no faster than soil is formed.
Under the natural cover of woods, burned over annually, as has unfortunately been the
custom in southern woods, each year the land lost 3 1/2 percent of rain and 0.06 ton of
soil per acre so that it would take 1,800 years to erode away 7 inches of soil. But where
fire was kept out of the woods and forest litter accumulated on the forest floor, the land
lost less than one-third of 1 percent of the rainfall. And, according to the calculations,
it would require more than 500,000 years to wash away 7 inches of soil. Such a rate of
erosion is indeed far below the rate of soil formation.
Here in a nutshell, so to speak, we have the underlying hazard of civilization. By
clearing and cultivating sloping lands-for most Of Our lands are more or less sloping-we
expose soils to accelerated erosion by water or by wind and sometimes by battle water and
wind. In doing this we enter upon a regime of self-destructive agriculture. The direful
results of this suicidal agriculture have in the past been escaped by migration to new
land or, where this was not feasible, by terracing slopes with rock walls as was done in
ancient Phoenicia, Peru, and China.
Escape to new land is no longer a way out. We are brought face to face today With the
necessity of finding out how to establish permanent agriculture on our farms under
cultivation before they are damaged beyond reclamation, and before the food supply of a
growing population becomes deficient.
In an underpopulated land such as ours, farmed extensively rather than intensively,
there will be considerable slack before privations on a national scale overtake us. But
privations of individual farm families, resulting from wastage of soil by erosion, are
indicators of what will come to the Nation. As our population increases, farm production
will go down from depletion of soil resources unless measures of soil conservation are put
into effect throughout the land.
We must be in possession of a certain amount of abundance to be provident: a starving
farmer will eat his seed grain; you will do it and I will do it, even though we know it
will be fatal to next year's crop. Now is the time, while we still have much good land
capable of restoration to full or greater productivity, to carry through a full program of
soil and water conservation. Such is necessary for building here a civilization that will
not fall as have others whose ruins we have studied in this bulletin.
A solution to the problem of farming sloping lands must be found if we are to establish
an enduring agriculture in the United States. We have only about 100 million acres of flat
alluvial land where the erosion hazard is negligible, out of 460 million acres of land
suitable for crops. Most of our production comes from sloping lands where the hazard of
soil erosion is ever present. This calls urgently for the discovery, adaptation, and
application of measures for conserving our soils.
In the results of the Statesville erosion experiment station we saw how a forest with
its ground litter was effective in keeping down the rate of soil erosion well within rates
of soil formation. Out of untold ages of unending reactions between forces of erosion that
wear down the land and forces of plant growth that build up the land through vegetation,
the layer of forest litter has proved to be the most effective natural agent in reducing
surface wash of soil to a minimum. Here is clearly our objective for a permanent
agriculture, namely, to safeguard the physical body of the soil resource and to keep down
erosion wastage under cultivation as nearly as possible to this geologic norm of erosion
under natural vegetation.
A few years ago I came upon a hill farmer in an obscure part of the mountains of
Georgia. He was trying to apply on his cornfield the function of forest litter as he saw
it under the nearby forest on the same slope and same type of soil.
It was for me a great experience to talk with J. Mack Gowder of Hall County, Ga., about
the fields he had cultivated for 20 years in a way that has caught the imagination of
thoughtful agriculturists of the Nation. We talked about the simple device of forest
ground litter and how effective it is in preventing soil erosion even on steep slopes, and
how he thought that if litter at the ground surface would work in the forest it ought also
to work on his cultivated fields along the same slope.
Mr. Gowder told me how, as a young man when he bought this steep wooded land more than
20 years ago, he hoped to avoid the soil erosion that was ruining farms on smoother and
better land of the country. He planned to do this by stirring his land with deep plowing
but without turning the soil.
In this way, he could leave his crop litter at the surface to do the same kind of work
that the forest litter does. Gowder chose a bull-tongue plow, only 4 inches wide, to do
the trick. He told me that his neighbors laughed at him for such foolish ways of plowing.
As a concession to customs of the region, he put in channel terraces with a slight grade
as a precaution against storm runoff from unusual rains. But, thus far, they have not been
needed.
Now Gowder is cultivating topsoil on slopes up to 17 percent whereas his ridiculing
neighbors have only subsoil to farm. They have lost all their topsoil by erosion.
Leaving crop litter, which is sometimes called stubble mulch or crop residue, at the
ground surface in farming operations is one of the most significant contributions to
American agriculture. Certain adaptations of the method need to be made to meet the
problems of different farming regions, but the new principle is the contribution of
importance.
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