The Carbon advocate. [volume] (Lehighton, Pa.) 1872-1924, 1879-08-23
FARMERS COLUMN.
whence Plants obtain Their Sup
plies Of Food.

Plants get part Of their food from the air,
through their leaves and other green parts,
the rest from the soil through their roots.
This is proven by vast amount of labor
ious and accurate experimenting, carried on
for tbe most part in thes European exp'ri-
mont stations, for the purpose of discovering
the laws Of plant nutrition and growth.
water.-plants have the power ofabsorb-
ing water through their leaves, but the bulk
of their supply comes, and must come, from
the atmosphere to the soil, and thence to
the plant through its roots.
The carbon of plants Is taken from the at
mosphere. The leaves absorb carbonic acid,
and with the aid of light wrest its carbon
and oxygen asunder, setting oxygen free,
and thus purifying the air, while they re-
tain the carbon. Carbon uuites with hydro
gen, oxygen and nitrogen, to make up tue
various tissues Of the plant, the root, stem,
Leaf, and seed, the wood and bark, the gluten,
starch, sugar, and 50 on. The atmosphere
supplies carbon far in excess ofthe demands
OF plants The best experiments Indicate
that the carbon is all, or nearly all, obtained
from the air. The source Of the oxygen and
hydrogen is not definitely settled. 1t is
very probable that the water absorbed
through the roots is the main, if not the
entire source of supply.
Our cultivated plants get the bulk Of their
nitrogen from the soil, through their roots.
Many years Of labor of the best investiga
tors. and many thousands of dollars have
been devoted to the study of the sources OF
the nitrogen of plant-lood. The theory
that plants avail themselves Of the free nj
trogen of the air, of which there are thou
sands of tons over every farm, must be re-
garded as wrong. The theory that plants in
general, and the "large-leaved" plants in
particular, as clover, turnips, corn, etc, OBJ
tain good deal of combined nitrogen lam
monia and nitrogen) from the air by their
leaves, is hardly tenable. The gain of nj
trogen from this source, seems to be very
small indeed. The most Of the nitrogen OF
our crops is got from the soil through the
roots. The soil gathers some nitrogen com
pounds from the air, however, and it is eX-
tremely probable that it assimilates free nj
trogen, and thus in two ways, stores up at
mospheric nitrogen for plant.food The nj
trates in the soil, formed mostly from the
decay of vegetable and animal matter, and
the chief natural sources of the nitrogen oI
plant-food. Ammonia, which, like nitric
acid, comes from vegetable debris and from
manures, as we'll as from the air, is alsc
used by plants. Other compounds of nitro
gen, no one yet knows just what or how
many, can also be asslmilated by plants.
The mineral ingredients of plants are de-
rived exclusively from the soil. OF these
potash, lime, magnesia, iron, phosphoric acid
and sulphuric acid, must be furnished to all
agricultural plants, through their roots and
by the soil, in order to their growth. Ifthe
available soil-supply of any one of these is
deficient, the whole crop must suffer. As
regards soda, silica, and chlorine, the ex
perimental evidence is not so decisive. a
small quantity Of chlorine has been proven
necessary for lhe perfection of some plants
Soda is needed in very minute quantities
fiat all, by crops. a little of silica is prob
ably necessary to the perfect blossoming and
ripening Of grain.
To sum up in a few words: "Air and wa
ter together yield the materials out of which
fully ninety to ninety per cent. ofcrop'
is built up The soil has to give for theil
nourishment only the two to eight per cent
of mineral matters, which remain as ashe'
when they are burned, and the one half tc
two per cent. of nitrogen which they also
contain. n."-American Agricu'i,UiSt.