The Savannah morning news., 1901-10-14
Rotation. Humus and Nitrogen.

1t is always pleasant for the cultiva
tor to find that his time honored Gus
toms are well based in science, says
American Gentlemen. The rotation of
crops, by which is meant cropping in
a cycle and not continuously, has long
been a recognized practice, and as our
knowledge of the nature and quality of
the soil increases we learn more and
more that the old practice was right.
Looking now to recent Investigations
by the Minnesota station, we find that
when wheat was grown continuously
upon the same soil for eight years there
was a loss of 1, 200 pounds per acre of
nitrogen, about 300 pounds being utiliz-
ed as plant food and 1,400 pounds lost
by the decay of the animal and vege-
table matter of the soil and the liberia
ton of the nitrogen as gaseous and So
luble compounds. During the eight
years of continuous wheat cultivation
there was a loss of over 81 per cent of
the total nitrogen of the soil. equiva-
lent to an annual loss of 175 pounds
per acre in addition to that used as
plant food.
When wheat was grown in a rotation
with clover and oats, five crops of
wheat being removed in eight years,
larger yields per acre were secured,
and the total loss of nitrogen from the
soil was reduced to 800 pounds, or about
450 pounds in excess of that utilized as
plant food. When corn was grown with
clover and oats in a rotation and farm
manure was used, the total loss of nj
trcgen from the soil for eight years
was less than 100 pounds in excess of
that removed as plant food.
When the oats and barley were
grown continuously the losses of nitro
gen from the soil were nearly as large
as when wheat was grown continuous
ly.
When corn was grown continuously
the loss of nitrogen from the soil was
less than half as large as when wheat
was grown continuously. When corn
is introduced into a rotation of crops
the losses of nitrogen are less than il
wheat were grown.
When wheat was grown continuously
there was an annual loss of over 1000
pounds per acre of humus, due to the
fermentation and decay of the animal
and vegetable matter of the soil. When
wheat was grown in rotation with
clover and oats, no material loss OF
humus from the soil occurred.
The loss of humus changed the physi-
cal properties of the soil. causing II
to be less retentive of moisture, light
er in color and heavier in weight per
cubic foot. During times of drought
the soil from the continuous wheat
cultivated plot contained less water
than the soil from the plot which pro-
duced wheat in rotation with clover.
Humus conserves the moisture of the
soil, while the rotation of crops, the
use of farm manures and the growing
of clover conserves the humus of the
soil.
When bare summer following is
practiced a heavier loss of nitrogen oc-
ours then when wheat is grown con-
tinuously. Summer following favors
the decay of the humus and the loss of
nitrogen. While larger crops of wheat
are produced after year of fallow this
increase is followed by a heavy loss
of the total nitrogen of the soil. Sum-
mer following rapidly exhausts the
soil of its nitrogen.
When the nitrogen and humus of the
soil were conserved by the rotation OF
crops and the production Of clover, an
increase of 20 bushels per acre of corn
and 56 bushels of wheat was secured.
Old wheat soils readily recuperate
when humus forming materials are re-
turned TO the soil, as in the use of
farm manures and the cultivation of
clover.
Thus do we also learn to better I'M
derstand how manure benfits the gar
den.