A dictionary of modern gardening - University Library

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MAN 363 MAN
are the manures that not only absorb
but retain moisture powerfully. The
following results of my experiments
throw some light on this point :
Pig dung evaporated to dry-~
ness at a temperature of
106°, and then moistened
with six parts of water, ^ 135'
,
which by a few hours' exposure to the
air subsides into a gray or black hue.
The first colour appears to arise from
the oxyde of iron which all soils contain,
being in the state of the red or
protoxide; by absorbing more oxygen
during the exposure, it is converted
into the black or peroxide. Hence one
required for being reduced
of the benefits of frequently stirring
to dryness again, at the
soils ; the roots of incumbent plants
above temperature i
abstract the extra dose of oxygen, and
Horse-dung under
circumstances
Common sail
similar )
i
90
75
reconvert it to the protoxide. Coal
ashes, in common with all carbonaceous
matters, have the power of
Soot
Rich soil
75
32
strongly attracting oxygen. Every gardener
may have observed how rapidly
Chalk
Poor soil (siliceous)
Gypsum
29
.... 23
18
a bright spade of iron left foul with
coal ashes, becomes covered with rust,
or red oxide.
These experiments point out a criterion
by which we easily ascertain the
All animal and vegetable manures
absorb oxygen from the air during pu-
comparative richness of any two given trefaction ? If it be required of what
soils or manures ; the most fertile will benefit this property is to plants, since
be most absorbent and retentive.
Some manures increase the growth
the gases are freely presented to them
in the atmosphere, it admits the ready
and vigour of plants by stimulating their answer, that they enjoy the additional
absorbent and assimilating organs. quantity which is thus collected to the
The stimulating powers of excremen- vicinity of their roots, without the lat-
i
,
,
j
titious manures arise from the
ammonia they contain.
salts of ter source being diminished; and that
plants are benefited by such additional
Sir H. Davy found vegetation assisted application to their radiculae has been
by solutions of muriate of ammonia (sal- proved by the experiments of Mr. Hill.
ammoniac), carbonate of ammonia (vol The question may also be asked,
atile salt), and acetate of ammonia. whether the roots have the power to
Night soil, one of the most beneficial extract the oxygen from its combina-
of manures, surpasses all others in the tion ? That they have this power ad-
abundance of its ammoniacal constimits of little doubt, since Saussure
tuents in the proportion of three to one, found that they were able to extract
It may be observed, that the nearer various saline bodies from their combi-
' any animal approaches to man in the nations ; not only extracting but selectnature
of its food, the more fertilizing ing in those cases where several salts
is the manure it affords.
were in the same solution.
Dr. Daubeny, the Oxford professor of
I
I
'
Carbonic [
I have no doubt that a languishing
plant, one, for example, that has been agriculture, has also shown that stronkept
very long with its roots out of the tian is rejected by barley, pelargoniums,
earth, as an orange tree recently im- and the winged pea.
ported from Italy, might be most rapid-
acid is also of benefit to
iy recovered, if its stem and branches plants, when applied to their roots in
were steeped in a tepid weak solution an advanced stage of their growth.
Animal and vegetable matters evolve
of carbonate of ammonia, and when [
planted, an uncorked phial of the so.- this gas whilst putrefying ; and I am
' lution were suspended to one of the not
aware of any manure that absorbs
branches, to impregnate the atmosphere it from the atmosphere, so as to be for
slightly with its stimulating fumes. that reason beneficial to vegetation.
Lime 1
I with
Manures are also of benefit to plants
by affording some of the gases of the
atmosphere to their roots in a concen
trated form. A soil, when first turned
up by the spade or plough, has generally
a red tint, of various intensity.
attracts it rapidly, but combines
it so strongly that it is useless to
the plant, until the carbonate of lime
so formed is imbibed and elaborated.
Manures assist plants by destroying
predatory vermin and weeds. This is