Heppner gazette. [volume] (Heppner, Morrow County, Or.) 1892-1912, 1911-04-13
LAND PLASTER AND ITS EFFECT
ON THE SOIL.

(By Professor II. " Tartar, Oregon Aeri
cultural College Experiment station.)
Land plaster, or gypsum. is a ma
tive sulphate of lime. 1t is a we'll
known crop stimulant yet 1t contains
neither nitrogen, phosphorus, no
potassium, the usual plant foods sup
Piled In commercial fertilizers. Ii
some localities it is used to a con
siderable extent According to the
estimates of DR.. Fl. 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 fertilizer for leguminous crops
AS evidence Of it's remarkable stimu
lating action on the growth of leg
umes, many instances are recorded
where the yield Of a clover or vetch
crop has been practically doubled by
a treatment with plaster at the rate
Of SO to 60 pounds per acre. This
fertilizer has also been used with sue.
cess by a 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 beneficial effect on heavy
clays by flocculation, though in this
action it is far surpassed by lime. II
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 a 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 1T is found that the
lime of the plaster is fixed in the soil
while 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 its 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-
of txyni
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
potash from these soils and hence
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 s
been claimed that the soil does not ,
respond to its application as readily |
as formerly. In other words, the sup {
ply of plant food material liberated c
by the action of the land plaster ap- q
pears to become depleted. Analyses |
Indicate that our Western Oregon t
clay loans contain an almost mex c
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
'aised to its use. One particular field, !
| sandy loan used for truck garden
ng, has come to our notice which has :
lad applications of land plaster for :
IS years at the rate of 200 pounds
Der acre and still responds readily .
o this treatment.