MORE ABOUT FERTILIZERS.
In the past we believed that fertilizers acted as plant foods and that
the substances to be applied must contain one or more of four elements
which are probably the most important to the plant, namely: Nitrogen,
phosphorus, potassium and calcium. Several other elements go to make up
the plants; but these are considered most difficult for the plant to
secure from the soil and were therefore of the most importance for the
farmer.
Trials, by experimental work with different plants, soon showed that
the forms of combination of these elements make a great difference. For
example, nitrogen is now applied either in the form of nitrate of soda
and of potassium, which is called saltpetre, or in the form of sulphate
of ammonia; or, it may be applied as organic matter in dried blood,
tankage, hoof- and horn-meal and even muck.
Both the nitrate and sulphate forms are readily dissolved, but the
nitrate form is the one in which plants take up their nitrogen, so that
either nitrate of soda or saltpetre is specially valuable for forcing
a quick growth. The effect may be seen upon plants in a very few days
after it is first applied. But sulphate of ammonia, although it will
dissolve, must be changed into a nitrate, in the soil, before the
plants can use it, and this probably takes several days, hence, it is
not quite so quick acting.
The organic forms of nitrogen vary much in their usefulness. The
nitrogen of dried blood or tankage is the most easily absorbed. These
substances are sometimes sown at seeding-time, and become useful later
in the season when the soil becomes warm. Other forms, however, as
muck, leather parings, etc., are used considerably in making some
low-grade fertilizers. Notwithstanding the tradition that you must bury
an old shoe at the foot of the vine, the nitrogen in these may never be
of very much value.
The phosphorus is found in fertilizers both in forms that will dissolve
and in forms that won’t. Acid phosphate and dissolved bone contain a
large portion of phosphorus in the form of a soluble phosphate of lime;
this is often marked on the bag as being equal to 12, 14, or 16 per
cent. of phosphoric acid. Ground phosphatic rock, also called “floats,”
and raw bone-meal contain phosphorus combined with lime in the form of
an insoluble phosphate.
Basic slag is still another form of phosphate of lime, which, although
insoluble, readily becomes available as plant food in the soil.
Potassium occurs in various forms of combination, one of the most
common being muriate of potash; another form is sulphate of potash.
Kainit is another fertilizer which contains potassium, and wood
ashes contain a small percentage. In all of these the potassium is
generally spoken of as potash and the first two are said to contain the
equivalent of 50 per cent. potash. Kainit usually contains 12 to 14 per
cent. Wood ashes may contain about 3 to 6 per cent. Kainit and muriate
of potash have an acid effect upon the soil, and it is wise to apply
them some time before the crop is to be sown, even the fall previous,
if the soil retains plant food fairly well.
The commonest kind of calcium is quick-lime or lump lime. When this is
“air-slaked” it becomes what is called carbonate of lime. Fifty-six
pounds of lump lime contain the same amount of calcium as 100 pounds
of air-slaked lime, and in using these it makes very little difference
whether we apply the quick-lime or the air-slaked, provided we apply
equal amounts of calcium and that the particles are equally small in
both cases. In other words, 56 pounds of quick-lime or 100 pounds of
air-slaked lime may be used, but both should be in as fine powdered
form as possible before they are sown.
Like every other fertilizer, lime is of no use until it is dissolved,
and the finer it is ground before it is applied the further it may be
spread and the sooner it will dissolve. It is seldom wise to apply more
than from one-half ton to a ton of quick-lime per acre at any one time;
and it is safer to apply this quantity every three or four years rather
than larger quantities at shorter periods. Lime should be applied to
the land when there is a crop upon it which can use it with advantage.
A crop like clover or alfalfa, which covers the land completely, will
make the best use of lime. It may injure potatoes, because it makes the
land more favorable for the growth of scab, a disease which attacks
potatoes.
Much money can be lost by the unwise use of fertilizers, and the best
way one can positively know whether it is wise to use them is to try
it thus, say, with radishes, lettuce, or beans; a patch containing two
or three rows may be fertilized in one way, the next one in another,
others with various mixtures and, in order to determine the values of
these it will be wise to leave untreated “check plats” between some
of the strips. The following outline will show how to make such an
experiment on about half an acre:
Plat 1.—Nothing[10]
·
· 2.—200 pounds nitrate of soda per acre in
· two or three applications.
·
· 3.—600 pounds acid phosphate.
·
· 4.—Nothing.
·
· 5.—100 pounds muriate of potash.
·
· 6.—100 pounds muriate of potash and 200
· pounds nitrate of soda in two or three
198 feet.· applications.
·
· 7.—Nothing.[10]
·
· 8.—100 pounds muriate of potash and 600
· pounds acid phosphate.
·
· 9.—100 pounds muriate of potash.
· 600 pounds acid phosphate.
· 200 pounds nitrate of soda.
·
· 10.—Nothing.
··············································
144 feet.
One hundred pounds per acre is one pound for 48 square yards, a strip,
say, one yard wide and 48 yards long.
It may be necessary to repeat the experiment several years, before we
can be sure what will give the best results; but we shall learn much
that will help even during the first year.
In mixing fertilizers, care must be taken not to mix those which
injure one another; thus nitrate of soda and muriate of potash, both
take up moisture from the air quite readily, and when mixed with other
substances are liable to make the whole mass pasty, or even to run
together and bake in the bag; these should be mixed but a short time
before they are to be applied. Nitrate of soda and acid phosphate, when
they are mixed and allowed to stand, become damp and act chemically
upon each other, and the result is loss of fertilizer elements into the
air; the same is true when basic slag and sulphate of ammonia are mixed
together.
We are frequently advised to apply fertilizers to the crop while it is
growing. Nitrate of soda is generally used in this way, and to aid in
spreading it, it is often mixed with acid phosphate. Now both of these
substances, as well as muriate and sulphate of potash, are likely to
burn the foliage of plants with which they come in contact; hence,
broadcasting these over growing plants on a damp morning is liable to
do serious injury to the foliage; it is safer to apply them with a
drill.
_Value in Fertilizers._—In estimating the value of fertilizers it is
the custom to speak of the unit of valuation. A unit is one per cent.
of a ton, or, in other words, 20 pounds. For example, if kainit
contains 12 per cent. of potash and is sold at $12.00 per ton, then
there are 12 units and they cost $12.00; therefore one unit costs
$1.00, and since the unit is 20 pounds, the actual cost of the potash
is 5 cents per pound. If muriate of potash, guaranteed to contain the
equivalent of 50 per cent. of potash, is selling at $40.00 a ton, then
we find that 50 per cent. potash is 50 units; if 50 units cost $40.00,
one unit will cost 80 cents, or in this form 20 pounds cost 80 cents;
therefore one pound will cost 4 cents.
Now, if these are prices free on board the cars at New York, and potash
is the thing we need, we must remember that in order to get equal
amounts of potash delivered to our own farm, we must pay freight and
haul four tons of kainit instead of one ton of muriate of potash. In
other words, with these figures the higher-priced fertilizer, counting
in dollars per ton, is really the cheaper article, counting in value.
Any one who will secure the latest fertilizer bulletin from the
nearest Experiment Station will usually find the approximate values
of one pound of nitrogen, phosphoric acid and potash in the different
fertilizers worked out in some part of the bulletin. These may be
used in deciding whether it is better to buy and mix the fertilizers
at home; then one may know what is going on the land and the form of
combination it is in.
Manure contains all of the elements we have discussed in more or less
fixed forms. The liquid manure from animals contains a large amount of
the nitrogen passed from the body and is of particular value. The most
useful parts of the manure are the ones which are easiest lost; hence,
if manure is piled and allowed to ferment, or if the water from the
roof of the barn is allowed to wash it, serious loss occurs.
A ton of fresh manure has all the value it ever will have, and if there
is a piece of land upon which it can be spread, it should be done at
once. The liquid manure should be soaked up by the bedding, and applied
at once to the land. The holding of manure in piles or pits always
causes loss of valuable elements. Sometimes we may have to hold it,
but every effort should be made to arrange the crop so that it can be
applied somewhere each day as made. Manure has a special value because
it furnishes humus, which greatly helps the physical condition of the
soil, and the bacterial and other microscopic life in the soil.
FOOTNOTES:
[10] NOTE.—If the yields of plats 1 and 7 do not agree closely, the
effect of the fertilizer can be closely estimated by comparing the
yield of each with the check plat nearest to it. Another interesting
experiment is to lime one-half of each plat.