The San Juan islander. [volume] (Friday Harbor, Wash.) 1898-1914, 1912-01-05
GROUND LIMESTONE: WHAT Is
IT AND WHAT Is ITS ACTION
ON THE SOIL?
(By Professor H. " Tartar, OF the
Department of Chemistry, 0. A. CD

(By Professor H. v. Tartar, OF the
Department of Chemistry, 0. a. CO
Oregon Agricultural College, Cor
Wallis, Ore.-Recently numerous In
Quiries have come to the writer re-
garding 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. It
is with view of correcting these
mistaken ideas that this article has
been written.
| Limestone is 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 it to form
a 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
Iplace 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
loughly air slaked lime is exactly the
same material as finely ground lime
stone. It is evident then that nc
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 been
eliminated; it's action on the organic
matter of the soil is less caustic; i
is more easily handled than quick
lime or slaked lime. For these rea-
sons finely ground limestone has
come into considerable use in several
of our eastern states.
Lime is an essential element OF
plant food for all higher plants. II
seems to be especially necessary In
the leaves and stems for the proper
elaboration of starch. The total
amount needed is small, varying Tor
different plants, and the supply IN
the average soil is ample for those
needs. Very rarely is 1t necessary
to add lime to soil simply to
serve as plant food. For this reason
lime has not been recognized as q
normal fertilizer constituent, Ike
nitrogen, phosphorus or potassium; II
serves as an amendment or supple
y ment to the soil mechanism.
The chief reason for applying lime
stone to soils is to correct or neu'
tralize the free acids in the soil. III
the decomposition and Fermentation
of the organic matter OF the SOL
chemical changes take place Wnicn
are accompanied by the formation
of certain acids such as carDonic
acid, nitric acid, and various organic
acids. This formation OF acids Is
analogous to the formation OF laclic
acid in the souring OF milk, OF acetlc
acid in vinegar from apple juice, ano
of the various acids in ensilage ano
sauerkraut. When there Is no car,
Donate of lime present In the SOL
much of these acids usually remain
in the free or uncombined state. Ger
tain farm crops, such as clover, AZ
sike, COW peas, soy beans and mos!
valuable legumes do not thrive Wen
lon soils which contain much Tree
acid. These crops can be often maze
to grow, it is true, on acid SOILS Dy
liberal application OF farm manure
and other fertilizers but under these
LuS ILL O6CA 6sSSAA AA-S
bacteria of such legumes do not mul
tiply and develop as they should
The presence of acids is inimical to
the action of the legume in taking
up atmospheric nitrogen, one OF the
main. functions of this kind Of plants
lin soil Improvement. When ground
Limestone is added to such soils i
chemically reacts with the acidic sub.
stances present to form neutral and
harmless compounds. It is to this
|neutralizing effect that ground lime.
lstone owes most Of its beneficial CT
fleets on certain crops.
! Again, in the decomposition Of the
Iorganic matter Of the soil chemical
Ichanges are brought about through
lcertain bacteria, known as nitrifyine
bacteria, whereby insoluble organic
nitrogen In farm manure and plant
residues il transformed into soluble
nitrate nitrogen, the form In which
It is available to plants. This very