The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1919-12-05
(Continued)
Application OF Plant Foods

phosphorus and potash, the three
chemical elements the lack Of which
is most likely to limit the plant
growth, and it will go far toward re-
ducing the quantity of plant food
necessary to apply in order to pro-
duce maximum crop Of potatoes.
Van Slyke states that the tops and
roots of red clover often contain 100
pounds each of nitrogen and potash
and SO pounds Of phosphoric acid per
acre. He further states Cop. cit, p.
$3.50 that a crop of alfalfa contains
120 pounds Of nitrogen, 100 pounds
of potash, and 80 pounds of phos-
phoric acid per acre.
II we compare these data with
those representing the chemical con-
stituents in a crop of clover or al
falfa, it becomes evident at once that
either of these leguminous crops re-
turns larger amount of nitrogen,
bphosphoric acid and potash to the
soil when plowed under than the po-
tatO crop removes. Such being the
case, the question at once arises as
to the necessity for any addition of
plant food to the crop. The answer
is that relatively small part of
these chemical elements contained in
the clover or alfalfa is Immediately
available to the plant; hence the ne
cessity of applying a certain quantity
of plant food that is Immediately
available.
Kinds Of Plant Food
Generally speaking, fertilizers may
be divided into two well-defined
groups, viz, organic fertilizers, such
as farm manures, dried blood, raw
ground bone meal and tankage, and
the strictly inorganic fertilizers, such
as nitrate of soda, sulphate of ammo
mia, acid phosphate, and the muriate
and sulphate of potash. Where farm
manures are available they may be
used at the rate of 10 to Is tons
per acre. Practices differ as to time
Of applying the manure to the potato
crop. On soils that do not leach
badly during the winter, it is well 70
apply the manure to the land before
fall blowing The same practice
should be followed on spring plowed
land; that is, the manure should be
applied before blowing. The next
best practice is to apply it to both
fall and spring plowed land prior to
fitting it for the crop.
Complete reliance should not be
placed on farm manures in the fer
tilization of land for potatoes. as they
are not well-balanced fertilizers.
Well-preserved barnyard manure
should contain approximately 10
pounds each of nitrogen and potash
and pounds of phosphoric acid per
ton. The application, therefore, of
10 tons per acre would be equal to
100 pounds each of nitrogen and
potash and SO pounds of phosphoric
acid, an amount considerably in ex-
cess of the need of a normal crop,
but not that of a maximum one. 1t
must be remembered that consid-
cradle part of the plant food con-
tanned in farm manures is not avail
able the first season. 1t is, there
fore, desirable on soils known to b.
deficient in phosphorus to reinforce
the manure by applying from 400 to
800 pounds Of commercial fertilizer
Analysing approximately per cent
of nitrogen, IL per cent of phosphoric
acid and 2 per cent of potash. This
insures an Immediately available sup
ply of the three elements most COM
monty lacking in the soil and neces-
sary for satisfactory plant growth.
On soils known to be infested with
potato-scab organisms it is generally
not advisable to use farm manures,
as it is almost certain to increase the
percentage of scab-infected tubers.
On soils deficient in organic mat
ter the application of farm manures
is, for several reasons, especially
beneficial to the crops which are
grown upon them. This is particu-
larly true in respect to the potato
crop. The principal benefits accru-
ing from the use of farm manures
are (1) the addition to the soil of a
considerable quantity of plant food,
(2) an improvement Of its physical
properties, 90 it's increased moist
ure-holding capacity, and "a the
increased bacterial action of the soil
flora, particularly Of the nitrifying
organisms.
Where farm manures are not |
available, or where, II ODta1naDle, the |
price is prohibitive, commercial fer
tilizers are found to be a fairly sat
isfactory substitute on lands well |
supplied with organic matter. In |
some localities commercial fertilizers
are used with such prodigality |
$4,000 to $500 pounds Of high
grade fertilizer per acre) that the
question may well be raised whether
such use is profitable. Prior to 1915
many potato growers in Aroostook
county, Maine, were in the habit of
using fertilizer Analysing to 5
per cent of ammonia 1873 to Al per
cent Of nitrogen, z to per cent
of phosphoric acid and to 10 per
cent Of potash. Since the former
source Of supply Of potash, has been
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