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dements required ean bo presented to the plants in a pure state, being always found in
combination xvith other elements, from which they require to be freed before they can
form the now combinations ncccssai-y to make them ayailable as food for plants.
1252. The substances used as manure act in various ways. “ Some of tlie substances
added to tlio soil,” Professor Solly obseiwes, “ act principally in a mcclianic,al way,
improving its to.xturc ; others are chiefly valuablo as sources of cai-bonio acid and
ammonia; whilst many ai'o useful as supplying salino and earthy matters in which tho
soil may bo doflcient. I t would be easy to divide all manures into these tliree classes;
but it is more convenient to divide them simply into the organic and the morgaiiie]
because many manm-es act in all those thi-ee ways at once, hnproving the texture of tlio’
soil, and supplying cai-bonic acid, ammonia, and saline matters.”— (Solly’s Rural Chemistry,
2nd ed., p. 170.)
1253. A ll manure, whether organic or inorganic, should he in a state of partial decomposition
when it is applied to the soil, in order that the elements of which it is composed
may be set at liberty, and he in a fit state to foi-m new combinations.
1264. The organs o f plants are so delicately constituted that they can only take tho
solid food requisite for their nourishmciit in the form of gas, or when held in solution
in wator. Thus carbon, which is a solid substance, can only be imbibed by plants in
tlie foi-m of carbonic acid gas, and the saline and earthy particles which ai-e required
must he dissolved in water. Water itself, when decomposed, supplies the plants with
hydrogen, and a part of their oxygen, the rest being obtained from the air. Thoir
nitrogen is principally supplied in the form of ammonia, in which state it is found
abundantly in the excrements of animals. But a considerable proportion of aU the
elements rcquh-ed for the food of plants, excepting the earthy and saline substances, is
procured fi-om tlie air.
Sect. I. O f Organic Manures.
1255. Organic manures include aU kinds of animal and vegetable substances, and they
may be considered as to tho theory of thcir operation, thcir specific kinds, and their
prcservation and application in practice.
SliBSEOT. 1. The Theory o f the Operation o f Organic Manures.
1256. Animal and vegetable substances, before they ean be used as manure fo r plants,
must ho in a state of decomposition, as, unless they are so, tho elements of wliich they
ai-c composed ai-c not in a proper state to afford wholesome food for plants.
1257. A ll organic substances, as soon as life is extinct, begin naturally to decay, a.s, if
this were not the ease, the world would soon become filled with the remains of dead
plants and animals ; whereas, aecordhig to the hoautiful economy of nature, no organic
substance lies inert, but as soon as it Ims ceased to be useful in one form, a process
begins by which it is placed in a state to he useful in another.
125S. The changes which organic matters undergo in decomposing have been an-angcd
under fom- heads, viz. fermentation, putrefaction, decay, and moulderirg, which are thus
explained hy Professor SoUy ; — “ The complicated changes which oi-ganie matters
undergo in decomposing ai-e generally divided into four separate classes, namely, fermentation,
01- the formation of now compound substances, by the partial decomposition
o f a compound, the change being induced or commenced in consequence of the prcsonoe
of some other decomposing matter. Putrefaction, or the complete decomposition of
organic matter and its conversion into different inorganic compounds, such as water,
ammonia, carbonic acid, snlphui-cttcd hydrogen, &c. Decay, a slow process of oxidation,
almost analogous to combustion, differing from putrefaction in being dependent on the
presence of free oxygen or air. This change is always accompanied by the evolution
of heat; mouldering, a change intermediate between putrefaction and decay, taking
place 111 organic matters exposed to the action of water, but not to that of air.” (S oW s
Rural Chemistry, 2nd edit., p. 171.)
1259. The proper time fo r applying organic matters to the soil is when they are in a
state of decay ; as at that period the elements of which they are composed are in the
most fitting state for forming new corahinations.
1260. The process o f decay is more rapid in some cases than in others ; but if any
fi-osh vegetable matter which contains sugar, mucilage, starch, or other of the vegetable
compounds soluble in water, be moistened, and exposed to the air, at a temperature of
from 55° to 80°, oxygen wiU soon be absorbed, and oarbonio acid foi-med; heat -ivill be
produced, and elastic fluids, principally carbonic acid, gaseous oxide of carbon, and
hydro-carbonate will bo evolved ; a dai-k-colourcd liquid, of a slightly sour or hitter
t.Tste, wiU likewise be formed; and if tlie process he suftercd to continue for a time
sufficiently long, nothing solid will rem.am, o.xcept earthy and salino matters, oolonrcd
black by chai-coal, The dark-coloured fluid formed in the formciitation always contains
acetic acid; and when albumen or gluten exists in the vegetable substance, it likew-iso
contains volatile alkali. In proportion as there is more gluten, albumen, or matters
soluble in water, in tho vegetable substances exposed to fermentation, so iu proportion
all other ch-cumstanccs being equal, will the process he more rapid. Pure woody fibre
.alone undergoes a change very slowly; but its texture is broken down, and it is easily
resolved into new compounds, when mixed with substances more liable to change, containing
more nitrogen and hydrogen. Volatile and fixed oils, resins, and wax, arc’morc
susceptible of change than woody fibre, when exposed to air and water; but much less
liable than the other vegetable compounds; and even the most inflammable substance.s,
by the absorption of oxygon, become gradually soluble in -«'ater. Animal matters in
general are more liable to decompose than vegetahlo substances ; oxygen is absorbed
and carbonic acid and ammonia formed in the process of thcir putrefaction. T-Jicy
produco fetid, compound, clastic fluids, aud likewise azote ; they afford dark-oolom-cd
acid and oily fluids, and leave a residuum of salts itnd earths mixed with cai-honaceous
matter.
Sdbsect. 2. O f the different Species o f Manures o f Animal and Vegetable Origin.
1261. The properties and nature o f the manures in common use should he known to
every cultivator; for as diflcrent manures contain different proportions of the elements
ncees.sary to vegetation, so they requh-o a different treatment to enabio them to produce
then- full effects in culture.
1262. All green succulent plants contain saccharine or mucilaginous matter, with woody
fibre, and readily ferment. They cannot, therefore, if intended for manure, he used in
too ft-csli a state. Hence tho advantage of digging in green crops, whether natural
or sown on piuqjosc ; they must not, however, be turned in too deep, othenvise fermentation
wiU be prevented by the compression and exclusion of the air. Green crops
should bo dug ill, if it be possible, when in flower, or at the time the flower is beginning
to appear; for it is at this period that they contain tho lai-gest quantity of easily soluble
matter, and that their leaves are most active in forming nutritive mtitter. Green crops,
pond-wecds, or the parings of hedges or ditches, require no preparation to fit thorn
for manure, nor does any kind of fresh vegetable matter. The decomposition slowly
proceeds beneath the soil ; the soluble matters are gradually dissolved ; and the slight
fei-mcntation which goes on, checked by the want of a fi-ee communication of air, tends
to render the woody fibre soluble without occasioning the rapid dissipation of elastic
matter. Wlien old pastures are broken up and turned into garden ground, not only
has the soil heen em-iched by the death and slow decay of the plants which have left
soluble matters in the soil, but the leaves and roots of the gi-asses living at the time, and
occupying so lai-ge a part of the surface, afford sacchai-ine, mucilaginous, and extractive
matters, which very soon become the food of the crop, and, from their gi-adual
decomposition, afford a supply for successive years. Tho roots of the grass also soi-vo
to keep the ground open, and act tike so many tubes tlu-ough wliich the atmospherio
air can reach the roots of the growing plants.
1263. Rape-cake, which is used with great success as manure, contains a largo
quantity of mucilage, some albuminous matter, and a small quantity of oil. This maiim-e
should be used fresh, and kept as dry as possible before it is applied.
1264. Mult dust consists cliiefly of tlie infant radicle scpai-ated from the gi-ain during
the process of turrdiig and drying tho malt on the kiln, fr-om which it falls down through
the holes in tho floor to tho space below, called the dunge (see Encyc. o f Cottage, Farm,
and Villa Architect, § 798.). Like rape-cako, it should be used fr-esh, and as diw as
possible.
1265. Sea-wecds, consisting of different species of Fuci, A'igæ, and Conférvæ, ai-e much
used as a manm-e on the sc.a-coasts of Britain and Ireland. In the Orkney Islands tho
F Ù C U S digitàtus is preferred, on account of its greater substance. When driven on shore
by the ^ winter storms or the gales of spring, it is collected and laid on tho land, into
which it is then ploughed. In summer it is burnt, with other Filci, into kelp. I’t is a
powci-fiil fertiliser, but its benefits do not extend beyond one or at most two seasons.
By digesting the common Fùous, which is the sea-weed usually most abundant on tho
co.T.st, in boiling water, one eighth of a gelatinous substance will be obtained, with
chm-acters similai- to mucilage. A quantity distiUod gave nearly four fifths of its weight
of water, but no ammonia ; tho water had an empyi-eumatio and slightly sour taste ; tho
•ashes contained sea salt, carbonate of soda, and cai-bonaceous matter. The gaseous
matter afforded was smaU in quantity, principally carbonic acid, and gaseous oxide of
c.arhon, with a little hydro-cai-bonate. This manure is transient in its effects, and docs
not last for more than a single crop ; which is easily accounted for fi-om the large quantity
of water, or the elements of water, which it contains. I t decays without producing heat
when exposed to the atmosphere, and seems, as it were, to melt down and dissolve away.
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