Catoctin clarion. [volume] (Mechanicstown, Md.) 1871-1940, 1879-11-27
AGRICULTU RAL.
Hu,nus. Old Views and New,

Hum us. Old Views and New
BY PROFESSOR G. G. CALDWELL.
The substance, consisting largely o
carbon, which we call humus, is he
terogenous mixture of products Of all
stages Of decomposition of vegetable
and animal sub tances in the soil, be-
tween the original remains of the
once living organisms and the final
products of their decay, carbonic acid
water and ammonia of nitric acid
It's proportion in our arabic soils
varies between the widest limits -
from | per cent. up to 40 or so; the
ordinary quantity ranges from to 5
per cent. This humus was once
thought to be the only, or at least the
chief, source from which the plant de-
rived the food for building up its or.
ganic part. But it has been clearly
demonstrated by both observation and
experiment that vegetation does not
depend on the soil for the carbon, its
most prominent constituent, and tina t
it can get this substance entirely from
the carbonic acid Of the atmosph ere.
Humus is, nevertheless, a useful III.
gredient of soils; we should be direct
" at variance with one of the farm.
er's most positive opinions If we
should affirm that it is worthless
garden soil, dark-colored with the
accumulation of humus derived from
its rich manuring is, in his view; the
best representative Of fertile soil; and
we can find valid reasons enough for
the belief without supposing that hu.
mus serves directly as plant food. 1t
greatly improves the texture of some
soils; in light. sandy soil it serves
as sort of binding material to hold
together the loose PARTICLES. and thus
as it were to granulate the soil; even
only l per cent Of humus added to
sand produces decided effect of this
kind; hence the popular belief that
humus gives body to light soil.
On the other hand, humus mixed
with clay diminishes its adhesiveness
makes it lighter and more porous, land
in every way improves its working
qualities. Humus by its dark color
favors the absorption of heat and the
early warming of the soil in Spring !;
consisting as it does Of vegetable sub
stance in process of decay, in prop.
erly drained and titled soil it is un-
ceasingly liberating, in very finely
divided state and in an excellent con-
dition for transcription by the new
vegetation, the ash-ingredients.pot
lime, phosphoric acid, ect. which make
up an essential though small part OF
every plant. Further than this, it
acts on the native stores Of these ash
ingredients in the soil ,dissolving them
and bringing them within reach Of
the plant; insoluble compounds Of
both potash aud phosphorlc acid in the
soil may, as has been proved by ex-
pertinent, be thus brought into solu.
ton.
Furthermore, numerous experl'
ments have shown that humus in
more ways than one may serve to In
crease the quantity of nitrogen that
becomes accessible to the plant in the
course of its growth; it contains more
or less combined nitrogen itself, de-
rived partly from the plant of which
it constitutes the remains, and partly
from the stock Of ammonia in the at
mosphere. Recent experiments by
Storer indicate that this nitrogen,even
though it may not have passed on in
to nitric acid, in which form the plant
appears especially to prefer its nitro
gen, is yet assimilable, and may be of
much value to the plant. The results
of some recent researches by Grand.
eau appear to furnish another reason
for the value of humus in the soil, as
an indirect provider Of plant food; to
that part of the humus which may be
extracted from it by solution of pot
ash or of carbonate OF ammonia he
gives the name of "black substance
(natiere noire), and to the presence
of an abundance of this in the So
called Russian black earth, which
probably corresponds very nearly
with our prairie soils at the West, be
attributes its remarkable fertility
This soil is not unusually rich in