Audubon Republican. [volume] (Audubon, Iowa) 1894-1925, 1901-07-11
FARM AND GARDEN.
MATTERS OF INTEREST TO
AORiCULTURISTS
some Cp-to-Dsts Hints About Cultivs-
lion OF tho Soil aud Yields Thereof
Horticulture, yitioulturs aud Fioricul-
turM
Notes on Soil Nitrogen.

Notes on Soil Nitrogen.
The question of soil nitrogen is one
that has been considered by some of
the most advanced investigators In the
domain of agricultural science. Lit
tie by little the puzzles have been made
plain, but the progress has been sur
prisingly slow. A generation of think
ers makes but little Roadway. The ag-
gregateis. however, large. Nitrogen has
so many forms and SO many changes
that 1t has proved most difficult ele-
ment to bind and analyze. To follow its
transformations and learn the causes
OF those transformations have proven
still more difficult. The experimenters
start out to prove one thing relative
to soil nitrate, and find, before they
finish their tests, that they have proved
a part of something else. A vast
amount of experimenting along these
lines remains to be done, even to reach
few certain conclusions.
For years the Wisconsin station has
been carrying on experiments having
in view the determining of a number
| Of things relative to nitric nitrogen in
the soil. Among the things to be
| found out were ~ the varia5leness
| OF nitric nitrogen in the soil during
the growing season; (2) the difference
in amounts of nitric nitrogen in fallow
! soil and soil in crops; (3) the infu-
| ence of cultivation on the formation
of this element; (4) the influence Of
nitrates on the thrifty versus The yell
low and withered plants; go tine va
riableness of the nitric supply IN and
between rows Of corn; (6) the differ
ence in supply of nitrogen in soil and
well water; Cd the discovery of an
| accurate method of determining the
nitric nitrogen in soils.
A few of the conclusions reached
| may be summarized as follows: In
dividing the soil into foot layers to a
depth of four feet, the greatest changes
were found in the foot next the sur
fact. In this top layer the supply of
nitric nitrogen varied greatly through
out the growing season. The amount
| in the spring was small, but increased
rapidly during the first three months
of growth, reaching their maximum
amount in June or July, according to
the kind of crop being grown upon
the fields. During July, when crops
are growing most vigorously, the nitric
nitrogen rapidly decreases till the first
| part of August, after which it remains
quite constant in the surface layer
In the other layers little change is
| observed.
The value of frequent cultivation is
| apparently in the more rapid accumu-
lation Of nitric nitrogen rather than in
the mere conservation o. moisture. 1t
was found that stirring the soil once
| per week, as compared with the stir
ring of it once in two weeks, left the
soil stirred, after 81 days, with 1916
as compared with 53.01 pounds of nj
trio nitrogen per million of dry soil.
| In the second series OF experiments
| which covered 258 days the soil stirred
once per week had acquired a mean
of 225.41 parts and that once in two
weeks 1879 parts per million of dry
soil showing the largest gains with the
more frequent cultivation. 1t was
found that stirring the soil to depths
of one inch two inches, three inches
IOul luS AhIst III vi
25S days resulted In an increasing
amount Of nitric nitrogen until the
three inch depth was passed. but that
cultivation four inches deep gave a
smaller nitrification than the three
inch depth did. Thus in soil stirred
once a week the action of the forces
that create nitric nitrogen is stimulated
exceedingly. The increase of these nj
trates results in a decided increase in
growth of plants, all of which has
hitherto been credited to better direc-
ton Of the water supply.
The amount of available nitrates af-
fects the thrift and color of the leaves.
From the experiments referred to we
draw the conclusion that leaves turn
sere because the supply of nitrates Is
virtually cut off; and this lessened sup
ply of nitrates is a provision of ma
ture to assist in the elaboration of
seed. The amount of nitric nitrogen
left in the surface foot of soil before
crops begin TO turn yellow for lack
Of available nitrogen becomes very
small, the amount found being .213
parts per million where oats were yet
green, and OPS parts per million where
they were turning yellow. In corn 1t
was found as low as SO parts where
corn was green, and 10 parts per mil
lion where it was strongly yellow. The
rapid growth OF stalks Just before ma
turity apparently has the result of TAX
ing out Of the soil about nine tenths
Of the nitrates available in the sur
face soil.
The amounts Of nitric nitrogen were
found greatest between the rows OF
corn, as they were coming into tassel,
and least directly beneath hills, except
in the surface six inches, and in the
fourth foot where the relations were
slightly reversed. The amounts of nj
trio nitrogen are less in the deeper
ground water wells of this vicinity
than In the soil, moisture of the fourth
foot, the nitric nitrogen being only
about one-third of the amount. Obser-
vations indicate that when the textural
equilibrium of soils is destroyed N
the presence of salts in solution,
refocculation and reorganization of the
soil may take out OF solution portion
OF the salts leaving smaller per cent
present after establishing the new
equilibrium.