The Way to an Enduring Agriculture
Our solution for safeguarding our soils on slopes where soil erosion by water is the
hazard is (1) to increase the rainwater-intake capacity of the soil by retaining crop
litter at the surface, soil improvement, crop rotations, and strip cropping on the contour
and (2) to lead away unabsorbed storm waters in channels of broad-base terraces into
outlet channels and into natural drainage channels. We have applied these measures during
recent years over millions of acres as you may see from an airplane when you fly over the
country. Near Temple, Tex., in the drainage of North Elm Creek, 174 farmers of
bordering farms formed a soil conservation association on a drainage basis, ignoring
property and county lines in the same way as runoff water ignores such arbitrary lines
(fig. 16). Terrace-outlet channels were laid out to carry water harmlessly through one
farm and another to natural drainage channels. One terrace-outlet system may serve in this
way as many as 5 farms. By this approach to conservation, it is possible to treat the land
in accordance with its adaptabilities and to control storm waters according to hydraulic
principles. This is indeed physiographic engineering that builds a lasting basis for a
thriving civilization.
FIGURE 16. This airplane view shows parts of six
different farms near Temple, Tex., where the farmers have banded together to combat
erosion as a community problem.
This does not mean that we have yet found the final answer to full control of soil
erosion. Our present practices may not yet stop erosion but will reduce it more and more
as application of measures is more and more complete. These measures and others will need
further improvement and adaptation to the problems as use of land becomes more and more
intensive. Wind erosion is a serious and destructive problem but restricted to a smaller
area of the country than water erosion. Wind erosion attacks level as well as sloping
cultivated land in semiarid parts of the country.
Wind erosion sorts the soil more thoroughly than water erosion, lifting fine and
fertile particles of soil aloft and leaving behind coarser and heavier particles that
become sandy hummocks, then sand dunes. Such was the case in the so-called Dust Bowl of
the Great Plains.
Control of wind erosion is based first upon a suiting of the land's use to its
capabilities and conserving all or most of the rain that falls on it. This calls for
contour farming except on flat lands. Appropriate measures include strip shelter belts of
crops, tillage practices that leave crop litter or residue at the surface, and rotations
suited to moisture supplies in the soil. These, with progressive improvement of
soil-management practices, will control wind erosion. It has proved a simpler task,
however, to control wind erosion than the less spectacular but more insidious water
erosion.
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