The central Presbyterian. [volume] (Richmond, Va.) 1856-1908, 1881-12-21
farm aud Garaeu.

TarM anu OafaEtl.
conducted by DR.. THOMAS POLLARD. State
Commissioner of Agriculture
Ground Limestone-Again.
We give the following communication
from DR.. Ruffner on an interesting sub
ject briefly discussed in our last.
DR.. Pollard. Commissioner of agriculture
Dear Sir,-I have observed what i.
said in late number of the Central
Presbyterian respecting the use of gro,lno
limestone as fertilizer. Unfortunately
differ with the scientific men and other
who pronounce the ground limestone
to be worthless, or nearly worthless as
manure. | have long believed that the
limestones which, by their disintregration.
furnish the mineral elements for rich
soil, must be complete manure. Last
winter l had little controversy with
Prof. Caldwell, of Cornell University, on
this point, and the matter ended by his
agreeing to make an analysis of each OF
our chief varieties of Valley limestones,
which form soils from very fertile to
poor. sent him specimens, and hope
to hear the results before long. 1t has
usually been assumed that limestone is
simply carbonate of lime, with occasional
additions of magnesia: and there have
really been very few thorough analyses.
Last year one sample of limestone was
analysed at the Connecticut Experiment
Station, with the following result:
Carbonate of lime, so per cent.
Carbonate of magnesa 81
Phosphate of lime,
Compounds of potash and soda l
Insoluble matters, 10
Water, IA ''
100
In this specimen the phosphate of lime
is worth 81 in ton, whilst the carbonic
acid, lime and magnesia, have considera-
BILE value, and the soda and potash
have very little. But no doubt it will
limestone which contain much larger
percentage of potash and phosphoric
acid, and hence will have commercial
value as complete manures.
The only question in my mind is as to
the relative economy of using burned
and ground limestone. Throwing out
the chemical value of burned lime in
certain cases, probably the ground lime
stone will prove to be more economical,
chiefly because it is cheaper to grind
than to burn. The ground limestone
may be little slower in its effects, but
not materially SO. At any rate the trial
is worth making; and whether it be used
ground or burned, the selection should
be made of the limestones which make
the best natural soil.
Dec. 9Th. W. II. RUFFNER.
We agree with DR.. Rufner that the
ground lime should be fairly tried in
comparison with that burned. 1t is
generally believed that burned limestone
acts in very important manner in dis
solving vegetable matter and mineral
matter in some degree also, and making
them available for plant food. If ground
limestone thus acts, it must be very
slowly, for as far as we know it has no
caustic property. We doubt very much
the economy of using ground limestone.
In view of its slow action we should
think it would require at least double
the quantity to the acre, of that burned.
We know that while so bushels. of burned
limestone is considered good dressing
for some land, that 300 bushels of mari
are frequently used to the acre, in view
to its slow solubility and tardy action.
L have used this quantity of mari con-
tanning rs per cent of carbonate lime.
We should not think that 81 worth
of insoluble phosphorate lime in
ton of limestone could do much good.
Using two hundred bushels to the acre
we should get only ten cents worth of
1T. The magnesia is scarcely worth any
thing, as soils almost always contain
enough for the wants of plants.
The DR.. speaks of lime as being
probably complete manure. I wish |
could think so-wbere is the ammonia
to come from but he probably means
complete mineral manure.
hope this discussion will lead to
fair trial of ground Limestone and
more general use of lime. And we ad-
wise those who can get it to use gas lime,