The Parma herald. (Parma, Idaho) 1903-1917, 1912-01-04
GROUND LIMESTONE: WHAT is
1T AND WHAT is ITS ACTION
ON THE SOIL7
(By Professor H. v. Tartar, of the
Department Of Chemistry, o. A. O.

Department Of Chemistry, o. A. CO
Oregon Agricultural College, Cor
wallis, Ore.-Recently numerous in
quiries have come to the writer re-
gardlng the nature and the agricul-
tural use of ground limestone. These
inquiries have shown that some farm
ers of the state have obtained enron
eous ideas regarding this material. 1t
is with view of correcting these
mistaken ideas that this article has
been written
Limestone is a more or less impure
form of carbonate of lime. Carbonate
of lime Is a chemical compound con-
tanning 40 per cent Of calcium, IL per
cent of carbon and >48 per cent of
oxygen. AS it occurs in nature it is
mixed with some impurities such as
sand, iron, alumina, phosphates and
often considerable quantity OF mag
nesium carbonate.
When this compound calcium is
heated to bright redness it decom-
poses into two compounds known
chemically as calcium oxid. a solid
substance, and carbon dioxide, a gas.
The commercial form of calcium
oxide is ordinary quick lime" 1t is
really lime stone from which all the
carbon and two-thirds of the oxygen
present have been driven off in case
GUS form by the aid of heat, the
"quick lime remaining being about
Sc per cent of the original amount
OF limestone used.
When exposed to the moisture OF
the air or soil quicklime rapidly takes
up water combining with 1t to form
chemical compound, calcium n.y.
droxide, which is mere water slaked
lime. This compound formed by the
uniting of quick lime and water is
the, same whether the shaking takes
place rapidly or slowly.
When air slaked lime is exposed
in the air or soil. carbon dioxid (the
same gas which is given off when
quick lime is formed from limestone)
| is gradually absorbed and calcium
carbonate is again formed. The thor
oughly air slaked lime is exactly the
same material as finely ground lime
stone. 1t is evident then that no
matter whether we apply quick lime
water slaked lime, air slaked lime OF
ground lime stone, the benefit de
rived during the subsequent months
or years is due to one compound
calcium carbonate.
Because OF the fact that carbonate
OF lime is the final substance formed
when quick lime or slaked lime are
added to soil, it would seem advisa
BILE to use finely ground limestone
| (lime carbonate) in the beginning
The limestone is also cheaper be
cause the cost of burning has beer
eliminated; its action on the organic
matter of the soil is less caustic; /
lis more easily handled than quicl
lime or slaked lime. For these rea
sons finely ground limestone hal
come into considerable use in severa
of our eastern states.
Lime is an essential element o
plant food for all higher plants. |
seems to be especially necessary II
the leaves and stems for the prope
elaboration of starch. The tota
amount needed is small. varying TO
different plants, and the supply Il
the average soil is ample for thos
needs. Very rarely is it necessar,
to add lime to a soil simply t
serve as plant food. For this reason
lime has not been recognized as
normal fertilizer constituent, Xix
nitrogen, phosphorus or potassium;
Iserves as an amendment or supple
ment to the soil mechanism.
The chief reason for applying lime
stone to soils Is to correct or net
tralize the free acids in the soil L
the decomposition and fermentatio
of the organic matter OF the so
chemical changes take place whic
are accompanied by the formatio
of certain acids such as carboni
acid, nitric acid, and various organi
acids. This formation of acids
analogous to the formation of lacti
} acid in the souring Of milk, of acct
. acid in vinegar from apple juice, an
, of the various acids in ensilage an
sauerkraut. When there is no ca
Donate of lime present in the so
much of these acids usually renal
in the free OF uncombined state. &c
tain farm crops, such as clover, a
sike. COW peas, soy beans and mos
valuable legumes do not thrive we
on soils which contain much fire
acid. These crops can be often mao
, to grow, it is true, on acid soils
liberal application of farm manu-
and other fertilizers but under thes
conditions the nitrogen gatherir
r bacteria OF such legumes do not mt
, tiply and develop as they shoul
y The presence of acids is inimical
' the action of the legume in. takiI
up atmospheric nitrogen, one OF Il
!, main functions OF this kind OF plan
! in soil improvement. When grour
u limestone is added to such soils
l. chemically reacts with the acidic gu
stances present to form neutral al
harmless compounds. 1t is to tn
6 neutralizing effect that ground lin
8 stone owes most Of its beneficial {
y fects on certain crops.
Again, in the decomposition OF q
n organic matter of the soil chemic
changes are brought about throui
certain bacteria, known as nitrifyil
= bacteria, whereby insoluble organ
D nitrogen in farm manure and pla
residues is transformed into soluf
= nitrate nitrogen. the form in viii
1t is available to plants. This We