The morning news. [volume] (Savannah, Ga.) 1887-1900, 1894-08-27
How, Plants Get Nitrogen From the
Air


The air we breathe is about four-fifths
nitrogen and one-ifth oxygen, says re-
cent Bulletin. We use the oxygen in
breathing but discard the nitrogen. 1t
has been regarded merely as a material
for diluting the oxygen. which would 9th
erwise be too strong for our use. All at
temptS, to economically render this nitro
gen of the air available for plant food,
by chemical means, have been unsuccess-
full Recently it has been discovered that
the so called leguminous plauts-cIovers
peas beans, lupines, vetohes, etc, can
take up this nitrogen of the air, and can
grow without being MANFRED with nitro
gen if MANFRED with phosphate acid and
potash.
The manner in which this nitrogen as
sanitation takes place has been carefully
and patiently studied by scientists and
although the details are not fully under
stood, the primary cause has been found.
1t is believed that plants are enabled to
get this nitrogen through the activity of
the lower forms of lite, bacteria or mi
crobeS, which cam only be seen with the
aid of a powerful microscope. These
organisms live in the soil, and are to be
found where leguminous plants have been
grown: They produce, or cause the plant
10 produce, little nodules, or tubercles,
on the roots. 1t is through these tuber-
Giles that the plant gets its atmospheric
nitrogen. The air enters the soil by
the numerous pores or openings in
it, which are produced by blowing,
cultivating and working the soil,
by the decay of rootlets. by earth worms,
etc. BY just what physiological processes
the nitrogen assimilation takes place is a
question still In dispute among scientists.
1t is sufficient for practical purposes TO
know that nitrogen is taken up from the
air by the growing plant directly or indi-
rectly; and that this nitrogen assimila-
tiOn takes place as a result of the life of
bacteria. IL is peculiar fact that few.
If any, root tubercleS are formed when
leguminous plants are MANFRED with nit
rogen; the plants must first hunger for
nitrogen before the tubercles are formed,
and the presence of tubercles indicates
that the plant is taking nitrogen from the
air
Now, curious as it may seem, there APP
pear 10 be different forms of bacteria for
different kinds of plants. Hence il some
times becomes neceSsaryto provide crops
with the necessary bacteria before they
can use the nitrogen of the air This IS
done by applying light dressing of soil
in which the kind of plants ii is wished
TO grow have been previously grown.
This is called soil incubation. 1t Is some
times necessary in growing crop on a
piece Of land for the first time in several
years. Suppose, for instance, that peas
which had been sown on land MANFRED
with phosphates and potash, but without
nitrogen, failed to grow luxuriantly. If
the oJher conditions we're favorable, the
inference would be that bacteria of the
right kind were lacking in the soil, and
light dressing of soil in which peas had
previously been successfully grown might
be applied. Such treatment as this has
been repeatedly tried with success on a
large scale-
These discoveries throw a new light on
green manuring and on the plants
best adapted for green manuring. They
recommend 1t more highly than ever be-
fore as a reuovator and a cheap
means of maintaining the fertility of soil
They show that while both leguminous
and non-leguminous plants enrich the soil
alike in humus-forning materials, in pro-
portion 10 the size of the crop, they differ
in respect to the source of their nitro
geuous materials. While non-leguminous
plants derive their nitrogen supply al
most exclusively from the soil,
leguminous plants may take theirs
largely from the air. Consequently, II
spurry, buckwheat, mustard, etc. mon