The morning news., 1897-07-26
The NutriGcatiOn of LeguminOus
Plants


Plants.
1t has been long known to cultivators
that the cultiva ton of plants like clover
and peas, tended to improve the fertility
of the soil, but just how these plants did
this was for a long time a controverted
question, writes Prof. w H. Massey, in
Practical Farmer. Many imagined for
long time that the plants of this order
had the power to absorb, by means of
their foliage, the free nitrogen of the air
But experiment proved that they did not
DO this, or at least did not benefit by the
free nitrogen that undoubtedly entered
the leaves with the air. Now as some of
our readers may not exactly understand
what we mean by the term free nitrogen,
We Will explain that the air is composed
OF two gases, nitrogen and oxygen and
that these are simply mixed not combin-
ed, and the oxygen and nitrogen are both
free gases. This mixture of gases also
penetrates the soil freely. a least. to the
depth that is cultivated. 1t is found, too,
that the air in the soil is always COM
posed of a larger portion of nitrogen than
that above ground.
On the roots of legumnous plants. such
as peas clover, vetches, etc, there are
found gall-like swelhngs, called the root
tubercles. Much attention has for num-
Der of years been given to the study of
the cause and the effect of these tubercles
on the pl9pt and the soil. They have
been ascertained tdsbe the work of minute
vegetable organisms inhabiting the SOIL
and are always more plentiful in soils
where these leguminous plants haye been
cultivated before. Prof Atwater of the
Middletown (ConnecticuO University and
Prof. Hellriegel in Germany, have done a
great deal of work in investigating the
nature of the root tqbercles and their re-
lation to the fixaton of nitrogen in the
soil by means of this class of plants
There is no longer any doubt that the
microscopic fungus plants that inhabit
these tubercles are the means by which
they are able to get the free nitrogen of
the air and fix it fin the soil for the use of
the succeeding crops. While the expert
ments of DR.. Atwater had proved that
the legumes did get nitrogen from the
air, the relation of the tubercles on the
roots to this acquisition was first sug-
gested by Helriegel and Wilfarth in Ger
many abouE 1886. Heilregel found that
plants OF peas growing side by side, one
would be vigorous while the other was
much less so.
In every instance he found that the Wig
orous plants all had tubercles on their
roots, while the feeble ones had none.
Plants grown in soil absolutely free from
nitrogen developed to the extent of the
nitrogen that the seed contained and per-
ishSd, but other plants Of the same lot
that were watered with an infusion of soil
water grew vigorously and had root tuber-
cles on them, but if the soil infusion was
first sterilized by heat so as to destroy
any micro-organisms that it might contain
no good effect was produced and no tu-
bercles were formed. 1t was plain from
Hellriegei's experiments % that plants
of peas growing in soil rich in nitrogen
as assimilated the combined nitrogen
just as well without the root tubercles as
with them, thus showing that the tuber-
cles were not needed TO assimilate the nj
trates in the soil; (2). He demonstrated
that the different species of legumes has
each it's own peculiar tuberce forming
organism, pea tubercles not injecting the
roots of other legumes and vice versa.
Following the lead of Hellriegel a mum
Der of investigators began to study the
root tuhercles and their work. Franks
experiments with various plants show that
the root tubercles on the bean did not aid
It in getting nitrogen. and could be only
considered as parasite, while on the pea
and some other legumes they are OF great
value. Frank concluded that the tuber-
Giles were not of themselves the agent
of the assimilation of nitrogen, but that
the presence Of these organisms stimu-
lated the plant TO make a greater growth
Few other Investigators agree with Frank
A series Of careful experiments by Pras-
mowsld showed that the inoculatlon of the
soil with the organisms was always fol-
lowed by the formation of tubercles and
the ACQUISITION Of nitrogen, and that while
plants Watered with a nitrogen solution
were vigorous, without tubercles, those
that had the tubercles We're much more
So and they acquired more nitrogen than
those watered with nitrogen. The expert
ments of Lawes and Gilbert at Rotham-
sted England, confirmed Hellriegels con-
clusions. They cultivated plants Q in
washed sand and fed with no nitrogen
(2) in same. but inoculated with soil in
fusion; go in rich garden soil The inoc-
ulated plants always developed tubercles
and fixed nitrogen, while those not inocu-
lated failed to do so. Without undertake
ing further TO review the various expert
ments in this direction, we will say that
the sum OF the results shows that such
plants as peas and clover not only are
able 10 use the nitrogen that may be In
the soil water, as other plants can. but
that they also can get a much greater
supply from the free nitrogen Of the air
by means Of certain microscopic plants Of
the nature OF ferments. that inhabit tuber-
cles on their roots. The fact that these
Organisms have this power Is now well es-
tabllshed. but Il seems that though such
organisms may exist In the soil, they do
not fx nitrogen except when growing on
the roots OF leguminous plant. As hxa-
ton occurs In connection with the roots
we oan readily see the significance OF this
for il enables W 70 get the benefit OF the
nitrogen and yet have the hay for food