Knoxville daily chronicle. [volume] (Knoxville, Tenn.) 1870-1882, 1881-04-14
WEEKLY CHRONICLE.
The-Action of Plaster.

Plaster.
as a fertilizer, is so mysterious In its action
that many of the wisest agricultural philos-
ophers have admitted it to be only an alb
s6rbent of ammonia, while others contend
that it combines with it. The question is
often asked: ''What effect has plaster on
the manure heap?" Mr.. Greeley went so
far as to affirm that plaster attracted ammo
MIA, not only in the manure heap, but di-
rectly from the atmosphere; but there are
those who do not assent to this view. Plas-
ter is sulphate of lime, being compound
of sulph1ric acid and lime, and the combi-
nation of the acid and lime is not easily
broken up. In the laboratory ammonia
does not drive the lime away from the sui
phuric acid, which clearly shows that it does
not react by giving up Its lime so easily
wnen mixed with manure. The supposltlon
is that suIphuric acid parts from the lime
and seizes the ammonia, thus forming sui
phate of ammonia while the lime, being
freed from the acid, is converted by the car
bonic acid, which is constantly being gen.
Grated, into carbonate of lime Plaster
shows wonderfully on clover, giving the
same result that ammonia (guano) produces
on wheat and corn; but when We
stop to consider the effects of the
plaster on clover we cannot admit
that the benefits We're obtained
by the attraction of ammonia, for it is now
clearly demonstrated that ammonia is not
special fertilizer for clover, but lime is one
of its principal necessities. 1t is the lime
that imparts the benefits; and in the case of
clover we plainly see that the theory of its
being the means of supplying ammonia is
not confirmed: Still, there may be some
truth in it, but as yet the subject is open for
more opinions What is SO very curious
with it is the fact that, unlike ordinary slaked
lime, but small quantity of it is required
to produce great effects. With lime, twenty
and forty bushels are often applied to the
acre, but with plaster one or two bushels are
often sufficient That it completely breaks
to pieces end disintegrates by chemical
action cannot be denied but this fact does
not convince every one that sulphete of
ammonia is found in all cases, as clover
is almost exclusively a lime and pot
ash feeder and requires, as stated
before, but very little ammonia We
may look in another direction, however,
and perhaps discover something on
which to found further theories. Sulphuric
| acid is the most powerful acid known, the
weaker acids being nearly always driven
| from their bases by it. But there are times
when the weaker acids are able to push it
| aside, and that is when they are applied hot.
| Now, carbonic acid is one of the feeblest
of all acids, and cannot take the place of
sulphuric acid; but sometimes, when heated,
it is able to displace the stronger acid. Car
bOnic acid has a great affinity for lime and
perhaps when plaster is mixed with manure
during the process of decomposition, when
heat is thereby generated it may under pos
sible peculiar circumstances seize the lime of
the plaster, freeing sulphuric acid, which, in
no no
manure. Heat is but the motion of the
atoms, and during the heating of the manure
heap hundreds of combinations take place in
it. SulphateS, nltrates, phOsphates and
chlOrides are formed over and over again
and any particular substance that may be
thereby set free, if it does not form a new
combination, at once escapes into the air or
else is absorbed and retained by some alb
s0rbent material placed therein for that pur-
pose. Experiments and observations have
confirmed one thing, however, and that is
plaster is a great absorbent 1t does not
possess this power i'll a dry state very much,
but when mOistened it absOrbs and retains.
May we not suppose that the rains bring
down ammonia to the earth, where it is held
10y the plaster absorbing and retaining it?
Having once absorbed it. like charcoal
heat is necessary to disengage it. which is a
slow process around the roots of the plants
but, while 1t retains the ammonia in its
| gaseous state III that way, it gives it up, by
| virtue of this gradual heat, just as it is
| needed by the plant, and no faster. In
| proof of this, it may be asserted that its
effect on sandy soils differs from that on
| heavy, close and compact soils, as the ever
heated sand causes the escape of the anon
! ia before it can all be appropriated by the
plant. 1t must not be overlooked, also. that
| ammonia itself, under certain conditions.
| acts on the soil chemically, rendering solu-
bic many substances which water, mas-
| sisted, could not dissolve. By these changes,
and not by the action of the rootlets, no
doubt the plaster is not only changed in
character, but assists in turn to perform
work outside of its ability to supply lime
and sulphuric acid to the growing plant
Many wonderful things are unfolded to the
chemist in the laboratory by experiment,
but there are still more wonderful changes
that occur in natures laboratory unknown
to him, and the process of supplying food
to plants when fertilizers are placed at their
roots is beyond his penetration, so far
While much is known, we have only gone
below the surface of science in that direc-
ton. What is the action of plaster" is as
yet not positively known, but it is our duty
to experiment and give our views. We are
certain of this, however, that plaster is the
cheapest of all fertilizers, and the farmer
who uses it freely will be benefited from
every crop on which he applies it.
p III. JACOBS, HammOnton, n. J.
ACTS OF THE LEGISLATURES.