There is a general belief among farmers that the roots of all
cultivated crops are very near the surface and that few reach a
greater depth than one or two feet. The first striking result of the
American investigations was that every crop, without exception,
penetrates the soil deeper than was thought possible in earlier
days. For example, it was found that corn roots penetrated fully
four feet into the ground and that they fully occupied all of the
soil to that depth.
On deeper and somewhat drier soils, corn roots went down as far as
eight feet. The roots of the small grains,--wheat, oats,
barley,--penetrated the soil from four to eight or ten feet. Various
perennial grasses rooted to a depth of four feet the first year; the
next year, five and one half feet; no determinations were made of
the depth of the roots in later years, though it had undoubtedly
increased. Alfalfa was the deepest rooted of all the crops studied
by the American stations. Potato roots filled the soil fully to a
depth of three feet; sugar beets to a depth of nearly four feet.
Sugar Beet Roots
In every case, under conditions prevailing in the experiments, and
which did not have in mind the forcing of the roots down to
extraordinary depths, it seemed that the normal depth of the roots
of ordinary field crops was from three to eight feet.
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