Lincoln County leader. [volume] (Toledo, Lincoln County, Or.) 1893-1987, 1911-05-05
LAND PLASTER AND ITS EFFECT
ON THE SOIL.


cultural College Experiment Station.)
Land plaster, or gypsum, is a ma
tive sulphate of lime.' 1t is we'll
known crop stimulant, yet it contains
neither nitrogen, phosphorus, nor
potassium, the usual plant foods sup
piled in commercial fertilizers. In
some localities it is used to a con-
siderable extent. According to the
estimates of DR.. H. w. Wiley, of the
United States Department of Agricul
ture, about $4,000 tons of ground land
plaster is used annually in this
country
Land plaster is now used in West
ern Oregon and Western Washington.
especially in the Willamette Valley,
as a fertilizer for leguminous crops
AS evidence of its remarkable stimu
lating action on the growth of leg
umes, many instances are recorded
where the yield of clover or vetch
crop has been practically doubled by
a treatment with plaster at the rate
of so to go pounds per acre. This
fertilizer has also been used with sue
cess by number of market gardeners
on general truck crops.
The reactions that take place in
the soil when land plaster is applied
have been studied by numerous in
vestigators. Physically, it is known
to exert a beneficial effect on heavy
clays by flocculation, though in this
action 1t is far surpassed by lime. It
has also been considered that land
plaster has the power to neutralize
soil acids, but experiments made in
the laboratory have indicated that it
does not have such an effect and
hence cannot be used as substitute
for lime in this regard. Originally.
benefits derived from applications
were attributed to its fixing" action
on certain compounds of ammonia
converting them into more stable
forms for the use of plants.
Many years ago, however, it was
observed in comparing analyses of
clover grown on plots treated with
plaster with those of the same plant
grown on untreated plots, that the
plastered clover contained more pot
ash, one of the most essential ele-
ments of plant food. A later investi-
gator states: "It is found that the
lime of the plaster is fixed in the soil
while a corresponding quantity Of
potash goes into solution" At the
present time 1t is generally consid
cred that the benefits of land plaster
are due to it's action in liberating
potash from some of the more in
soluble materials of the SOIL
In connection with some soil stud
les test has been made on a num-
ber of typical Oregon soils, including
Willamette Valley clay loans, red hill
soils of the foothills, and Eastern
Oregon silt loans, as regards the
liberation of soluble potash by land
plaster. In every instance it has
been found that the plaster releases
acts as an indirect potash fertilizer.
This fact, together with the fact that
plaster encourages the growth of GER
tain nitrifying organisms in the soil
which are beneficial to plant growth,
probably explains it's beneficial action
on Oregon soils.
In some localities in the United
States where plaster has been used
for a long period of years it has
been clhimed that the soil does not
respond to it's application as readily
as formerly. In other words, the sup
ply Of plant food material liberated
by the action of the land plaster ap-
pears to become depleted Analyses
indicate that our Western Oregon
clay loans contain an almost mex
haustible supply of potash and if it
can be rendered more available
through moderate applications of land
plaster without the accumulation OF
any injurious products in the soil, it
would seem no objection can be
raised to it's use. One particular field,
sandy loan used for truck garden
ing, has come to our notice which has
had applications Of land plaster for
% years at the rate of 200 pounds
per acre and still responds readily
to this treatment
SOIL INCUBATION WITH
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