Press Bulletin No. 22.
Nitrogen as a Fertilizer.
(BY H. K. MILLER.)
This important element is essential to plant life and
while it is abundant in the elementary form, it is, never-
theless, the most costly material which enters into the
composition of commercial fertilizers. The high cost is
due to the fact that ordinary plants can utilize nitrogen,
only when it is in combination with other elements, and
there is no economical process known by which the nitro-
gen of the air can be combined directly with other ele-
ments. Fortunately we have the means of obtaining
nitrogen, by an indirect method, from the atmosphere,
of which, this element constitutes about seventy-eight
per cent. This may be accomplished through the agency
of bacteria. These are found in the soil, and under
proper conditions multiply with amazing rapidity. They
April 15th, 1902.
develop only on the roots of leguminous plants, such as
clover. cowpea, vetch, velvet bean, etc. Here they make
use of the nitrogen of the air, absorbed by the soil, and
convert it into compounds which are taken up by the
plant. On the roots of the plants are produced nodules
that are frequently very numerous and variable in size.
This method of restoring nitrogen to our soils is becom-
ing more generally appreciated as it furnishes this ele-
ment at the least possible cost.
The effect of nitrogen on'a plant is very marked. It
promotes a rapid growth of leaf and stem, and tends to
produce a large, green, succulent plant. While a plant is
in this condition, with a large supply of available nitro-
gen present in the soil, the formation of buds and flowers
is retarded, and the flowers are not only diminished in
numbers but many of them are rendered stirile, so that
they produce no seed. A plant which grows up with an
abundant supply of nitrogen is also less capable of with-
standing a drought, and begins to burn when the moisture
supply becomes limited.
Nitrogen does not merely act as a stimulating agent to
the plant but enters into composition with the plant,
forming albuminoid and other nitrogenous compounds.
Plants grown on a soil well supplied with nitrogen are
much richer in the above compounds than those grown
on poor soil.
It is highly probable that nitrogen must be in the
form of a nitrate before a plant can make use of it.. In
the soil there are a great variety of micro-organisms and
some of these have the power of converting various sub-
stances, containing nitrogen, into nitrates, so that most
nitrogenous compounds when applied to the soil are
acted upon by these bacteria, and, through this vi-
ial agency, are converted into nitrates. For the nitrogen
of fertilizers we are dependent upon sodium nitrate, sul-
phate of ammonia, or various organic compounds, such
as blood, bone, cotton seed meal, tankage, fish scrap, etc.
It will now appear that the source' from which the
nitrogen of a fertilizer is derived is a matter of great im-
portance. If nitrate of soda is used all the nitrogen is
immediately available. If sulphate of ammonia is used
it may become rapidly available on certain soils, slowly
available on others, and on still others it may exist in an
unavailable form so long as to be useless to the crop for
which it was applied. In the case of the organic sub-
stances we find the nitrogen of some much more readily
converted into nitrates than that of others. Much. de-
pends upon the nature of the soil and on the kind of
bacteria present. We are just beginning to appreciate
the importance of the action of these bacteria, and we
may expect far reaching results from investigations along
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