Mrs. Grundy. (Tracy City, Tenn.) 1903-1930, 1914-11-05

The need of lime for Tennessee soils
has been clearly shown in Tennessee
Station Bulletin 81. Although most
of our soils are deficient In lime, the
valleys of Tennessee are underlaid
with rich deposits Of lime rock, ard of
dolomitic lime rock, the latter being
limestone carrying large percentages
Of magnesium carbonate
Crushed dolomitic limestone Is by
product OF extensive mining opera
tons in this state. and the magnetism
lime rock can, therefore, be obtained
very cheaply. Furthermore, there are
areas In this state where dolomfte is
abundant and easily obtained for homo
crushing, while limestone is either
scare or absent. For these reasons
the question Of relative values Of the
two iimestones is one of great inn
portance to the farmers of this state.
While the usual run of dolomitic
limestones analyze less in total car
Donates than most of our limestones,
the greater efficiency of magnesium
carbonate in neutralizing soil "acid.
ity" gives our average dolomitic
limestone value corresponding to 100
pounds of limestone for each 90 pounds
Of dolomitic limestone. In other words,
our average dolomitic limestone is
more efficient in the extent of it's neu-
tralization of soil "acidity" than equiv
alent amounts of our average lime
stone.
Certain Investigations in this and
In foreign countries have shown that
large excess of magnesia over lime
In the soil is not beneficial to plant
growth, and for this reason the ques-
ton Of the advisability of the use of
dolomite for some soils has been a
debatable one Recent Investigations
at the Tennessee Station have shown,
however, that due to the fondness Of
the magnesia of dolomite for sole
ious substances in the soil, magnesium
carbonate unlike calcium carbonate.
can not remain In the soil, but is de-
composed. The substance formed
from magnesium carbonate soil treat
ment Is much less soluble than the
original dolomite and can not, there
fore. be so readily obtained by plants.
Experiments have shown that when
dolomite LIS applied the calcium car
Donate is subjected to leaching in ap-
probable amounts, whereas the mag
nesia after conversion to insoluble
forms is largely conserved. It would
take long period Of the continued
use of dolomite In the amounts or
dinarily used to effect this accumula-
ton of magnesia In large excess over
lime, and this station, therefore, sees
no reason why dolomite should not be
recommended for agricultural uses
when applied as ground stone as we'll
as limestone, when applied in amounts
not exceeding four or FIVE tons per
acre. The megnesian limestone is not
well adapted to burning, and it should
not be applied as burnt material in
ordinary cases.
BY utilization of the cheap mag
nesian lime rock by-product, present
land values could be materially and
economically increased by the use OF
dolomite to established conditions
which would permit better growth of
ieguminous crops. Moreover, in later
years, after the sou has been built up
and crop production increased, any
further limestone required could be
done with pure limestone, the cost of
which will probably be less and more
easily borne by farmers who may have
benefited financially from the original
modest outlay for dolomitic treat
ments. It would be well, however, for
farmers to receive individual advice
from their station as to the practice
most advantageous for their separate
needs'-W. M. Macsntire, Tennessee
Experiment Station.