Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1882-07-01
AGRICULTURAL PAPERS.
A SERIES PREPARED ESPECIALLY FoR
TIE "REcoRD-UHIcF."
Presenting instruction Contained in Leet-
ures from the Chair OF Agricult-
ure, state University.


ration Of vegetable and organic matter was
one of the original means OF soil formation.
When plants cease to grow, and die, they
begin to decay, and are incorporated with
the soil either as vegetable mold or hu-
mus. Daring the transformation OF organic
matter into vegetable mold or hnmus
numerous Gcids are formed, which exert
solvent and other effects upon the soil par
ticles. Both humus and vegetable mold
have high capillary and bygroscopic CO.
eficients. Humus has high absorbtive
power and Is powerful oxidizing agent.
They both improve the mechanical comPo-
stion OF soils; inasmuch as sandy soils are
rendered more retentive of water, and
hence less liable TO drought while heavy
clay soils, when vegetable matter is incor-
porated with them, become less compact,
are easier titled and drained, and do not
when sufficient vegetable matter is present
-6szure and cake up when drying. The
physical properties of soils, then, are i'm
proved in every case by the Incorporation
of reasonable amount of vegetable mat
ter with them. Much of
THE ORGANIC MATTER OF VEGETATION
Is made up simply OF the elements of water
and csr6onie acid. Cellulose, sugar, dex-
trire, etc, are part of this class OF sub
STAGES. 1t viii be remembered that cellu-
lose, sugar and starch pass naturally, by
fermentation, into dextrine which, being
soluble in water, is availble for plant nutri.
ton. Many OF the vegetable acids also
contain only the elements of water and
carbonic acid, and are, it is thought, under
certain conditions mutually transformable
into those and other substances by the or
ganisms Of the plant. These organic bodies
are known by the general term OF carlo.
hydrates. With the exception Of the vege-
table acids they may generally all be found
in the unaltered state in SOLE. Especi-
ally is this so with cellulose, which under
certain conditions takes very long time to
decompose. Dried straw, pieces OF wood,
cornstalks, etc, may often remain for
year or more in the soil without being SEN
sibly changed. They must all, however, in
due time decompose and become part OF
the soil proper. Humus is the product OF
DEoOMPosING VEGETABLE MATTER
Under certain conditions Of oxidation. Its
general appearance differs with the condi.
lions Of formation Vegetable mold, peat,
muck, etc., are all but different modifcs-
tions of hamus. The humus of the first
stages of decomposition is brown, and when
treated with water forms brown colored
solution. This may be noticed in winter
In forests, where the pools of water which
are filed with decsying leaves almost inva-
riably have q brown coffee color. The
waters flowing through tule swsmps show
the same characteristic color. This is due
to the presence OF ulmic acid, which Is SOL |
uble in water. and which will presently be |
spoken of. When this brown modification |
Of humus decays under water, and with |
imperfect soeess of air, the black humus Is
formed. This is the color of the decayed |
matter of peat beds and OF the lower strata |
of tule soil The brown and black humus |
each contains a characteristic organic acid.
They are known as ulmic and humic acid |
respectively. II the brown humus be |
boiled with alksli the ulmic acid is dis |
solved and may be precipitated from the |
solution by the addition of muriatic acid.
The solution of ulmic acid, as we have al |
ready said, is brown that of humic acid,
which may be prepared from black humus
In the same way, is black. humio acid |
may also be prepared by treating members
of the celiuiose group-cellulose, sugar,
starch, etc.-with strong acids or alkalies. |
These two acids-ulmic and humic-are |
composed of the same elements, but in |
slightly different proportions. The one is |
formed naturally when the decaying body |
has free access TO air, the other,
HUMIC ACID,
When the full supply Of air is cut off by |
saturation with water or other causes. |
Although these bodies are chemically diff |
ferent, yet their difference is hardly carried |
any further than as o distinction and, in |
fact, all of the acids formed by decsyipg !
vegetable matter have been included under |
the one general term "humus acids" and |
are sommonly spoken Of as the humus !
9ronn" ~. .ne liquids from which these /
two acids have been separated by the adai'
ton of acid, there remain still two ACIDS, |
and which are mutually transferable, by
oxidation and reduction, into one another
They are known as aprocrenIc and creme
acids. Aprocrenic acid is brown, and Is
formed from crenio acid by oxidlzing 1t.
Crenic acid is colorless, Is reduction
product, and hence exists IN the subsoll,
and out of access of the free air. Apro-
crenic acid is formed in the surface soil
and if subsoil be turned up the colorless
crenic acid is immedia tely transformed by
oxidation into brown aprocrenic acid
Aprocrenic acid is, we see, an oxidlzing
agent, and evidently acts as such in the
soil. Like ferric oxide fred oxide Of lroD)
- NTH re and a
transformed into lower oxide, crenic acid,
which Immediately absorbs more oxygen
from the air with the formation of apro.
crenic acid. Hence, by the mutual trans
formation of crenic and aprocrenio acids the
soil ia provided with another
AVAILABLE oxIpIzING AGENT.
The reverse process goes on in the subsoil,
for the crenic acid extracts oxygen from
any highly oxidized body it meets, and
converts it into lower and often highly
injurious oxide. These acids are not only
agents of oxidation and reduction, but they
are products of them also. They may be
prepared from humus by treating it with
3 strong oxidizing agent, as nitro acid.
By being thus prepared their existence
and individuality have been most satisfac-
torily proven. Most of the humus COM
pounds are acid in property, but in the
soil they do not give acid reactions when
the air has free access TO the soil. This is
probably owing to their being combined
with some base in the form OF neutral salts.
These bodies are altered to the acid state
by treatment with alkalis /; and it some
times happens that soils containing much
carbonate of potash. soda, lime or of
ammonia, have considerable amount Of
acid humus bodies, and are then known as
"sour" soils. Such soils are unfit for Gull
tivation, and must be abandoned, or else
sweetened," by adding some substance to
"sweeten" or neutralize the free acid.
Lime and mari are the most available SUBJ
stances for this purpose. 1t is curious
fact that if the sulphate of lime Gypsum,
plasterl be added, the "sourness seems TO
be aggravated. The real cause of this is