The progressive farmer. [volume] (Winston, N.C.) 1886-1904, 1900-10-02

uOuS cultivation without adding ma
nure or growing a crop of legumes
would in time exhaust the soil of it's
plant food.
But soils too rich in humus become
sour and this checks the operations
of soil baceria. This is seen in muck
soils.
Nitrification can only take place in
a feebly alkaline medium. In an acid
condition of the soil, said acidity
must be overcome by the use Of lime
before nitrifcation can actively be-
gin.
A heavy dose of lime by unduly in
creasing the alkalimity of the soil,
may at first check or suspend nitri-
fication until said lime has been con-
verted into carbonate. This, how
ever, takes place rapidly, diminish
ing in turn its strong alkaline prop
critics and permitting nitrifcation to
commence more actively than be-
fore
The nitrifying ferments grow only
in the presence of air. The effect of
stirring and pulverizing the soil is to
aid nitrifcation, bringing the oxygen
Of the air into more immediate con-
tact with the nitrifying organisms.
Exact experiments have further
Ior,,O,,C4,,a+o1 NJ
law, i. e., that the effect of cultiva-
tion is to markedly increase nitrifi-
cation, and in a ratio proportionate
to its thOroughness and frequency.
Bacteria of all kinds, including the
nltrifying organism, grow only in
the presence of moisture. In a dry
soil nitrifcation cannot take place,
hence in periods of drouth where the
superficial layers of the soil for a
depth of several inches become dry
nitrifcatiOn is suspended on the
other hand, an excess of water pre-
vents nitrification by excluding air i;
hence waterlogged soils must first be
drained before they become proper
nitrifying beds. In a wet soil not
only is nitrifcatiOn inactive or en-
tirely suspended, but the opposite
process of dentrifications take place,
with the loss of nitrogen in the free
gaseous condition.
The function of underdrains is
thus not only to withdraw the eX-
cess of subsOil water, but also by the
downward movement of the same to
draw air into the soil and thus SUD
ply oxygen to the nitrifying bacteria.
Nitrates are very soluble and are
easily Ieached out of soils by rains.
This loss is greater in sandy soils
than in heavier kinds; it is greater
from fallow land than from lands
covered by vegetatiOn hence if we
would prevent nitrates from being
leached out of soils, it is important
to keep the ground covered with
some crop throughout the year, sum-
mer and winter.
In view of the rapid disappearance
of nitrates from the soil, nitrate Of
soda as a fertilizer should be applied
in small quantities while the crop is
growing. The custom therefore of
introducing nitrate of soda with the
seed is a most wasteful operation.
The amount of nitrates lost from
an unmanured field at Rothamsted,
kept fallOw and free from weeds, was
an average of three successive years
SO pounds per acre per annum the
corresponding loss from wheat land,
an average of 10 years, was 1O%
pounds per acre per annum, or less
than one-third the loss from fallow
land.
The effect of sed, as compared with
wheat, in still further preventing
losses of nitrates from the soil, is
still more marked, as shown by the
experiments at Rothamsted and else
where.
The nitrifying organism cannot
multiply except in the presence
among other elements of phosphoric
acid and potash. Nitriffcation is ac-
cordingly aided by applications OF
mineral fertilizers.
Furthermore, the ability of crop
to utilize the nitrates of the soil is
considerably diminished when there
is a deficiency of available mineral
constituents, especially of potash
and phosphoric acid. Experiments
at Rothamsted, England, have shown