The Marietta journal. [volume] (Marietta, Ga.) 1866-1909, 1902-06-19
PLANT FOUJ t. -Il1NTS
Nitrogen and the Way In
Which It Is Absorbed.
STATE CHEMISTS LETTER NO. 4

STATE CHEMISTS LETTER NO. 4
Actual Quantities of Plant Food In
! SoiIs-What Determines the Crop
Producing Power of the Soil, Etc.
interesting and instructive Treatise.
Naturally the nitrogen we find in the
| plant by analysis next claims our at
! tention. AS | told you in my last let
| ter that there are nearly eighty gal
| Ions of nitrogen in one hundred gal
| Ions CT air, you would quite naturally
| eXclaim that there would be no need
to bother about providing nitrogen for
the crops, as they ought to be able to
| obtain all they want from the enor-
| nous oceans of it floating all around
and about them. Yes, one would natur-
ally suppose SO, but alas, it is not true;
| the plant is helpless to feed on the nj
trogen around it inAthe air, no mat
| ter how thirtsy it may be for it. 1t is
| like the shipwrecked sailor in the open
boat at sea, though parched and dying
with thirst, yet he can not Stake his
thirst, though there be nothing but
| water, water, all about him.
1t seems as though there were Ger.
tain malice in Nature in so constitut-
Ing plants that they cannot take the
nitrogen out of the air directly, yet
perhaps it is good thing they cannot,
| because if they could, life would be so
easy that we probably would not exert
| Ourselves as much as we should. Nj.
| trogen being the most expensive ele.
| ment of plant food, if it were provided
| free of cost like the carbon hydrogen
and oxygen, we could grow such enor-
nous crops at SUCH small cost, that the
| cost of living would be so reduced, that
a man would not have the same urgent
stimulus behind him to work and to
labor that he now has.
The Form in Which Plants Absorb
Nitrogen.
/ But to return to our subject, the
! plant requires nitrogen, but it cannot
take it through its leaves; it has to
|
| der for the roots to take it up, the nj
| trogent must be combined with nitrate.
| 1t must be in the form of nitrate of soda.
or nitrate of lime, or nitrate of mag
nes1a, or nitrate of potash, or some
other form of nitrate before the plant
can utilize it. If we put any organ.
1c matter containing nitrogen into the
| soil, either vegetable or animal, as cot.
ton seed meal, blood, meat, or even
If we pillow under green crops, they will
begin to decay and purify in the soil,
until the nitrogen which they con.
tain in the form of protein (about
which l wrote you so much last YEAR,
is changed into a number of other
| forms, being finally converted into a
nitrate otter the decay of the ooriginal
sustance has been fully completed.
| AS a nitrate it is in condition
where it dissolves easily in water, and
| is then absorbed by the root hairs
and drawn up into the circulation of
the plant. Now the vast majority of
| plants have to obtain their nitrogen
1
ed, but there are few favored plants
! which are able to obtain their nitrogen
out of the air through the instrumen.
tally of certain minute organisms or
microbes in the soil. We will have
more to say of this later on. When the
organic matters l have described
above, animal or vegetable, as cotton
seed meal, blood meat, manure or
turned under green crops decay in the
soil, the carbon and hydrogen which
are contained in them are not ali.
| sorbed like the nitrogen through the
roots into the plant, the plant does
not get its supply of carbon and hy-
drogen in that way. They simply re.
/ main in the soil to form what is known
as the humus of the soil, or the de.
cayed organic matter of the soil. which
improves its mechanical. condition.
gives it dark or black color, and
serves as an excellent retainer of
moisture and heat in the soil. Refer.
ring now to the analysis of a rich soil.
which l gave you in my last letter. we
find that besides the organic SUBJ
stance about which we have Just been
talking, there are also the Inorganic
or mineral substances, such as we
found in the ashes of the plant we first
analysed.
| The Various Elements Found in the
| Soil.
The most abundant substance of all
these mineral or ash elements in the
soil we find to be silica, or as you are
! quainted with it, sand. You will re.
member there was in this particular
rich soil 71.55 pounds of silica out of
every 100 pounds, and yet the wheat
plant grown on this soil only contained
two and three-Quarters pounds of sill.
ca out of every 100 pounds, and even
this was not absolutely essential to
the health and growth of the plant.
Although we find alumina in the coil
we find none in the plant. Alumnia
is one of the principal elements of a