Evening star. [volume] (Washington, D.C.) 1854-1972, 1861-06-14
THE EVENING STAR.
What Do We Piow For:

What Do We Plow For?
suoh was one Of the questions suggested as
IN appropriate subject for q prize essay. It
h question OF considerable Importance, and
called out twelve essays. One Of them was
awarded the prize, and published in the Feb
ruary number. The other eleven essays are
before n, and Ii will not be uninteresting to
glance ut some Of the principal reasons as
signed for this fundamental agricultural oper-
alton.
!. We pillow to bury the weeds, grass, and
2. We pillow to loosen and pulverise the land.
All soils, but especially those Of a olsyey ma
furs, have a tendency to consolidate, and soon
become too firm and compact, for the tender,
hair-like roots Of young plants to enter. The
soil may contain all the ,plant-fOod required,
but II 1t is 30 hard that the roots cannot pene-
trate, 1t will be of no avail. 1t is locked Ip.
Flowing 10 the key that unlOcks the store
house. The pillow is inferior to the spade, be-
cause IL does not break up and pulverise the
soil 90 thoroughly. If we had a digging ma
chine that could be worked by horses or steam,
as We undoubtedly shall have before many
years, 1t would soon supersede the pillow.
8. We pillow to let in the sun and air. In
nearly all soils there is large amount of
inert inorganic matter which could be rem
dered available plant-food by fermentation or
decomposition. This is accelerated by the
admission Of air. Like water, air will pene-
trate all porous bodies Large Jumps of sugar
are long in dissolving, because the water has
access only to the outside; but crush it and let
the water get at all its particles, and they are
dissolved with great rapidity. So of the soil,
IT 1t Is in Jumps, the air cannot get at it, but
loosen II and render it porous by blowing,
narrowing, rolling, &C., and the air will be
brought in contact with the particles of or
gsnic matter, and decompose them. 1t will
also disintegrats the inorganic matter of the
SOIL; and render more or less of it available as
food for plants. 1t must not be forgotten, too,
that the roots Of plants need air.
The air contains ammonia and carbonic acid
and 1t Is a well known fact that porous bodies
VIII attract these gases Thus Theodore de
Saussure found that charcoal heated to red
ness and plunged while hot into mercury, and
afterward, when cold, without being exposed
to the atmosphere, plunged into ammoniacal
gas absorbed ammonia equal to ninety times
lis volume. That is TO say, a cubic foot of
charcoal would absorb ono hundred pounds of
ammonia, or as much as ten tons of ordinary
barn-ysrd manure contains. The power OF
fresh charcoal for absorbing and condensing
ammonia Is due tn its porosity. Spongy or
porous platinum will absorb so much HYDRO
gen gas that the heat evolved by its conden-
sation will ignite IL. Now, while porous soil
Possesses no such power, there can be little
doubt that it does absorb ammonia and other
gases BY the mere attraction which one par
ticle OF matter has for another. This power is
" tut dulOuut OF surface eXpOecQ
10 the air, and consequently the more the soil
IL com ninuted, the more Il is broken ND and
loo'ened, the greater will be its power of at
traction.
Most soils also, contain substances which
nave chemical affinity fer ammonia Prof
Way says:
81 find that clay is SO greedy of ammonis
that, If air charged with carbonate ammonia
% az to be highly pungent, is passed through
tube filled with fragments of dry clay, every
PARTICLE OF the gas (ammOnia) is arrested -
inns power OF clay to absorb ammonia from
the air Is ascribed by Prof. Way to the pres
snce OF double silicste of lime and alumipa
and he thinks one ressen of the benefit of the
application Of lime is the formation of this
double silicste. OF course, the more such soils
are stirred, the more their particles are ex.
posed to the air, the more ammonia can thew
absorb from the atmosphere. This power Of
soils to attract ammonia from the atmosphere
one principal cause Of the we'll known ben.
sft Of summer following.
We pillow to incorporate manure with the
soil. The more thoroughly this 10 done the
better The earbonic acid generated by the
dsoom position Of humus has a good effect in
diantegrating the mineral matter in the soil
Inc soil may be regarded us a stomach in
which the food Of plants is digested and rem.
dsred assimilabls. It is important, therefore
that the manure should be well mixed with
the soil.
b. We pillow lin the fslD to expose the soil I,
the pulveriIing action Of the frost in winter
% disturb the eggs and larvs Of insects anc
expose them TO the cold -G,us,,s Fnr,nSr