DEFICIENCIES OF SOILS, MEANS OF RESTORATION, ETC.
As will be seen by referring to the analyses of soils on p. 72, they
may be deficient in certain ingredients, which it is the object of
mineral manures to supply. These we will take up in order, and endeavor
to show in a simple manner the best means of managing them in practical
farming.
ALKALIES.
POTASH.
[Do all soils contain a sufficient amount of potash?
How may its deficiency have been caused?
How may its absence be detected?
Does barn-yard manure contain sufficient potash to supply its deficiency
in worn-out soils?]
_Potash_ is often deficient in the soil. Its deficiency may have been
caused in two ways. Either it may not have existed largely in the rock
from which the soil was formed, and consequently is equally absent from
the soil itself, or it may have once been present in sufficient
quantities, and been carried away in crops, without being returned to
the soil in the form of manure until too little remains for the
requirements of fertility.
In either case, its absence may be accurately detected by a skilful
chemist, and it may be supplied by the farmer in various ways. Potash,
as well as all of the other mineral manures, is contained in the
excrements of animals, but not (as is also the case with the others) in
sufficient quantities to restore the proper balance to soils where it is
largely deficient, nor even to make up for what is yearly removed with
each crop, except that crop (or its equivalent) has been fed to such
animals as return _all_ of the fertilizing constituents of their food in
the form of manure, and this be all carefully preserved and applied to
the soil. In all other cases, it is necessary to apply more potash than
is contained in the excrements of animals.
[What is generally the most available source from which to
obtain this alkali?
Will leached ashes answer the same purpose?
How may ashes be used?]
_Unleached wood ashes_ is generally the most available source from which
to obtain this alkali. The ashes of all kinds of wood contain potash
(more or less according to the kind--see analysis section V.) If the
ashes are _leached_, the potash is removed; and, hence for the purpose
of supplying it, they are worthless; but _unleached_ ashes are an
excellent source from which to obtain it. They may be made into compost
with muck, as directed in a previous chapter, or applied directly to the
soil. In either case the potash is available directly to the plant, or
is capable of uniting with the silica in the soil to form silicate of
potash. Neither potash nor any other alkali should ever be applied to
animal manures unless in compost with an absorbent, as they cause the
ammonia to be thrown off and lost.
[From what other sources may potash be obtained?
How may we obtain soda?
In what quantities should pure salt be applied to the soil?]
_Potash sparlings_, or the refuse of potash warehouses, is an excellent
manure for lands deficient in this constituent.
_Potash marl_, such as is found in New Jersey, contains a large
proportion of potash, and is an excellent application to soils requiring
it.
_Feldspar_, _kaolin_, and other minerals containing potash, are, in some
localities, to be obtained in sufficient quantities to be used for
manurial purposes.
_Granite_ contains potash, and if it can be crushed (as is the case with
some of the softer kinds,) it serves a very good purpose.
SODA.
[If applied in large quantities will it produce permanent
injury?
In what quantities should salt be applied to composts? To asparagus?]
_Soda_, the requirement of which is occasioned by the same causes as
create a deficiency of potash, and all of the other ingredients of
vegetable ashes, may be very readily supplied by the use of _common
salt_ (chloride of sodium), which consists of about one half sodium (the
base of soda). The best way to use salt is in the lime and salt mixture,
previously described, or as a direct application to the soil. If too
much salt be given to the soil it will kill any plant. In small
quantities, however, it is highly beneficial, and if _six bushels per
acre_ be sown broadcast over the land, to be carried in by rains and
dews, it will not only destroy many insects (grubs, worms, etc.), but
will, after decomposing and becoming chlorine and soda, prove an
excellent manure. Salt, even in quantities large enough to denude the
soil of all vegetation, is never _permanently_ injurious. After the
first year, it becomes resolved into its constituents, and furnishes
chlorine and soda to plants, without injuring them. One bushel of salt
in each cord of compost will not only hasten the decomposition of the
manures, but will kill all seeds and grubs--a very desirable effect.
While small quantities of salt in a compost heap are beneficial, too
much (as when applied to the soil) is positively injurious, as it
arrests decomposition; fairly _pickles_ the manures, and prevents them
from rotting.
[What is generally the best way to use salt?
What is nitrate of soda?
What plants contain lime?]
For _asparagus_, which is a marine plant, salt is an excellent manure,
and may be applied in almost unlimited quantities, _while the plants are
growing_, if used after they have gone to top, it is injurious. Salt has
been applied to asparagus beds in such quantities as to completely cover
them, and with apparent benefit to the plants. Of course large doses of
salt kill all weeds, and thus save labor and the injury to the asparagus
roots, which would result from their removal by hoeing. Salt may be used
advantageously in any of the foregoing manners, but should always be
applied with care. For ordinary farm purposes, it is undoubtedly most
profitable to use the salt with lime, and make it perform the double
duty of assisting in the decomposition of vegetable matter, and
fertilizing the soil.
Soda unites with the silica in the soil, and forms the valuable
_silicate of soda_.
_Nitrate of soda_, or cubical nitre, which is found in South America,
consists of soda and nitric acid. It furnishes both soda and nitrogen to
plants, and is an excellent manure.
LIME.
The subject of _lime_ is one of most vital importance to the farmer;
indeed, so varied are its modes of action and its effects, that some
writers have given it credit for every thing good in the way of farming,
and have gone so far as to say that _all_ permanent improvement of
agriculture must depend on the use of lime. Although this is far in
excess of the truth (as lime cannot plow, nor drain, nor supply any
thing but _lime_ to the soil), its many beneficial effects demand for it
the closest attention.
[Do all soils contain enough lime for the use of plants?
What amount is needed for this purpose?
What is its first-named effect on the soil?
Its second? Third? Fourth? Fifth?
How are acids produced in the soil?]
As food for plants, lime is of considerable importance. All plants
contain lime--some of them in large quantities. It is an important
constituent of straw, meadow hay, leaves of fruit trees, peas, beans,
and turnips. It constitutes more than one third of the ash of red
clover. Many soils contain lime enough for the use of plants, in others
it is deficient, and must be supplied artificially before they can
produce good crops of those plants of which lime is an important
ingredient. The only way in which the exact quantity of lime in the soil
can be ascertained is by chemical analysis. However, the amount required
for the mere feeding plants is not large, (much less than one per
cent.), but lime is often necessary for other purposes; and setting
aside, for the present, its feeding action, we will examine its various
effects on the mechanical and chemical condition of the soil.
1. It corrects acidity (sourness).
2. It hastens the decomposition of the organic matter in the soil.
3. It causes the mineral particles of the soil to crumble.
4. By producing the above effects, it prepares the constituents of the
soil for assimilation by plants.
5. It is _said_ to exhaust the soil, but it does so in a very desirable
manner, the injurious effects of which may be easily avoided.
[How does lime correct them?
How does it affect animal manures in the soil?]
1. The decomposition of organic matter in the soil, often produces
acids which makes the land _sour_, and cause it to produce sorrel and
other weeds, which interfere with the healthy growth of crops. Lime is
an _alkali_, and if applied to soils suffering from sourness, it will
unite with the acids, and neutralize them, so that they will no longer
be injurious.
2. We have before stated that lime is a decomposing agent, and hastens
the rotting of muck and other organic matter. It has the same effect on
the organic parts of the soil, and causes them to be resolved into the
gases and minerals of which they are formed. It has this effect,
especially, on organic matters containing _nitrogen_, causing them to
throw off ammonia; consequently, it liberates this gas from the animal
manures in the soil.
3. Various inorganic compounds in the soil are so affected by lime, that
they lose their power of holding together, and crumble, or are reduced
to finer particles, while some of their constituents are rendered
soluble. One way in which this is accomplished is by the action of the
lime on the silica contained in these compounds, forming the silicate of
lime. This crumbling effect improves the mechanical as well as the
chemical condition of the soil.
4. We are now enabled to see how lime prepares the constituents of the
soil for the use of plants.
[Inorganic compounds?
How does lime prepare the constituents of the soil for use?
What can you say of the remark that lime exhausts the organic matter in
the soil?]
By its action on the roots, buried stubble, and other organic matter in
the soil, it causes them to be decomposed, and to give up many of their
gaseous and inorganic constituents for the use of roots. In this manner
the organic matter is prepared for use more rapidly than would be the
case, if there were no lime present to hasten its decomposition.
By the decomposing action of lime on the mineral parts of the soil (3),
they also are placed more rapidly in a useful condition than would be
the case, if their preparation depended on the slow action of
atmospheric influences.
Thus, we see that lime, aside from its use directly as food for plants,
exerts a beneficial influence on both the organic and inorganic parts of
the soil.
5. Many contend that lime _exhausts_ the soil.
If we examine the manner in which it does so, we shall see that this is
no argument against its use.
[How can lime exhaust the mineral parts of the soil?
Must the matter taken away be returned to the soil?]
It exhausts the organic parts of the soil, by decomposing them, and
resolving them into the gases and minerals of which they are composed.
If the soil do not contain a sufficient quantity of absorbent matter,
such as clay or charcoal, the gases arising from the organic matter are
liable to escape; but when there is a sufficient amount of these
substances present (as there always should be), these gases are all
retained until required by the roots of plants. Hence, although the
organic matter of manure and vegetable substances may be _altered in
form_, by the use of lime, it can escape (except in very poor soils)
only as it is taken up by roots to feed the crop, and such exhaustion is
certainly profitable; still, in order that the fertility of the soil may
be _maintained_, enough of organic manure should be applied, to make up
for the amount taken from the soil by the crop, after liberation for its
use by the action of the lime. This will be but a small proportion of
the organic matter contained in the crop, as it obtains the larger part
from the atmosphere.
The only way in which lime can exhaust the inorganic part of the soil
is, by altering its condition, so that plants can use it more readily.
That is, it exposes it for solution in water. We have seen that
fertilizing matter cannot be leached out of a good soil, in any material
quantity, but can only be carried down to a depth of about thirty-four
inches. Hence, we see that there can be no loss in this direction; and,
as inorganic matter cannot evaporate from the soil, the only way in
which it can escape is through the structure of plants.
[If this course be pursued, will the soil suffer from the use
of lime?
Is it the lime, or its crop, that exhausts the soil?
Is lime containing magnesia better than pure lime?
What is the best kind of lime?]
If lime is applied to the soil, and increases the amount of crops grown
by furnishing a larger supply of inorganic matter, of course, the
removal of inorganic substances from the soil will be more rapid than
when only a small amount of crop is grown, and the soil will be sooner
exhausted--not by the lime, but by the plants. In order to make up for
this exhaustion, it is necessary that a sufficient amount of inorganic
matter be supplied to compensate for the increased quantity taken away
by plants.
Thus we see, that it is hardly fair to accuse the _lime_ of exhausting
the soil, when it only improves its character, and increases the amount
of its yield. It is the _crop_ that takes away the fertility of the soil
(the same as would be the case if no lime were used, only faster as the
crop is larger), and in all judicious cultivation, this loss will be
fully compensated by the application of manures, thereby preventing the
exhaustion of the soil.
[Is the purchase of marl to be recommended?
How is lime prepared for use? (Note.)
Describe the burning and slaking of lime.]
_Kind of lime to be used._ The first consideration in procuring lime for
manuring land, is to select that which contains but little, if any
_magnesia_. Nearly all stone lime contains more or less of this, but
some kinds contain more than others. When magnesia is applied to the
soil, in too large quantities, it is positively injurious to plants, and
great care is necessary in making selection. As a general rule, it may
be stated, that the best plastering lime makes the best manure. Such
kinds only should be used as are known from experiment not to be
injurious.
_Shell lime_ is undoubtedly the best of all, for it contains no
magnesia, and it does contain a small quantity of _phosphate of lime_.
In the vicinity of the sea-coast, and near the lines of railroads,
oyster shells, clam shells, etc., can be cheaply procured. These may be
prepared for use in the same manner as stone lime.[AG]
_The preparation of the lime_ is done by first burning and then slaking,
or by putting it directly on the land, in an unslaked condition, after
its having been burned. Shells are sometimes _ground_, and used without
burning; this is hardly advisable, as they cannot be made so fine as by
burning and slaking. As was stated in the first section of this book,
lime usually exists in nature, in the form of carbonate of lime, as
limestone, chalk, or marble (being lime and carbonic acid combined), and
when this is burned, the carbonic acid is thrown off, leaving the lime
in a pure or caustic form. This is called burned lime, quick-lime, lime
shells, hot lime, etc. If the proper quantity of water be poured on it,
it is immediately taken up by the lime, which falls into a dry powder,
called _slaked lime_. If _quick-lime_ were left exposed to the weather,
it would absorb moisture from the atmosphere, and become what is termed
_air slaked_.
[What is air slaking?
If slaked lime be exposed to the air, what change does it undergo?
What is the object of slaking lime?
How much carbonic acid is contained in a ton of carbonate of lime?
How much lime does a ton of slaked lime contain?
What is the most economical form for transportation?]
When _slaked lime_ (consisting of lime and water) is exposed to the
atmosphere, it absorbs carbonic acid, and becomes carbonate of lime
again; but it is now in the form of a very fine powder, and is much more
useful than when in the stone.
If quick-lime is applied directly to the soil, it absorbs first
moisture, and then carbonic acid, becoming finally a powdered carbonate
of lime.
One ton of _carbonate of lime_ contains 11-1/4 cwt. of lime; the
remainder is carbonic acid. One ton of _slaked lime_ contains about 15
cwt. of lime; the remainder is water.
Hence we see that lime should be burned, and not slaked, before being
transported, as it would be unprofitable to transport the large quantity
of carbonic acid and water contained in carbonate of lime and slaked
lime. The quick-lime may be slaked, and carbonated after reaching its
destination, either before or after being applied to the land.
[What is the best form for immediate action on the inorganic
matter in the soil?
For most other purposes?]
As has been before stated, much is gained by slaking lime with _salt
water_, thus imitating the lime and salt mixture. Indeed in many cases,
it will be found profitable to use all lime in this way. Where a direct
action on the inorganic matters contained in the soil is desired, it may
be well to apply the lime directly in the form of quick-lime; but, where
the decomposition of the vegetable and animal constituents of the soil
is desired, the correction of _sourness_, or the supplying of lime to
the crop, the mixture with salt would be advisable.
_The amount of lime_ required _by plants_ is, as was before observed,
usually small compared with the whole amount contained in the soil;
still it is not unimportant.
OF LIME.
25 bus. of wheat contain about 13 lbs.
25 " barley " 10-1/2 "
25 " oats " 11 "
2 tons of turnips " 12 "
2 " potatoes " 5 "
2 " red clover " 77 "
2 " rye grass " 30 "[AH]
[What is the best guide concerning the quantity of lime to be
applied?
What is said of the sinking of lime in the soil?
What is plaster of Paris composed of?
Why is it called plaster of Paris?]
The amount of lime required at each application, and the frequency of
those applications, must depend on the chemical and mechanical condition
of the soil. No exact rule can be given, but probably the custom of each
district--regulated by long experience--is the best guide.
_Lime sinks in the soil_; and therefore, when used alone, should always
be applied as a top dressing to be carried into the soil by rains. The
tendency of lime to settle is so great that, when cutting drains, it may
often be observed in a whitish streak on the top of the subsoil. After
heavy doses of lime have been given to the soil, and have settled so as
to have apparently ceased from their action, they may be brought up and
mixed with the soil by deeper plowing.
_Lime should never be mixed with animal manures_, unless in compost with
muck, or some other good absorbent, as it is liable to cause the escape
of their ammonia.
PLASTER OF PARIS.
_Plaster of Paris or Gypsum_ (sulphate of lime) is composed of sulphuric
acid and lime in combination. It is called 'plaster of Paris,' because
it constitutes the rock underlying the city of Paris.
[Is it a constituent of plants?
What else does it furnish them?
How does it affect manure?
How does it produce sorrel in the soil?
How may the acidity be overcome?]
It is a constituent of many plants. It also furnishes them with
sulphur--a constituent of the sulphuric acid which it contains.
It is an excellent absorbent of ammonia, and is very useful to sprinkle
around stables, poultry houses, pig-styes, and privies, where it absorbs
the escaping gases, saving them for the use of plants, and purifying the
air, thus rendering stables, etc., more healthy than when not so
supplied.
It has been observed that the extravagant use of plaster sometimes
induces the growth of _sorrel_. This is probably the case only where the
soil is deficient in lime. In such instances, the lime required by
plants is obtained by the decomposition of the plaster. The lime enters
into the construction of the plant, and the sulphuric acid remains
_free_, rendering the soil _sour_, and therefore in condition to produce
sorrel. In such a case, an application of _lime_ will correct the acid
by uniting with it and converting it into _plaster_.
CHLORIDE OF LIME.
[What does chloride of lime supply to plants?
How does it affect manures?
How may it be used?
How may magnesia be supplied, when wanting?
What care is necessary concerning the use of magnesia?]
_Chloride of lime_ is a compound of _lime and chlorine_. It furnishes
both of these constituents to plants, and it is an excellent absorbent
of ammonia and other gases arising from decomposition--hence its
usefulness in destroying bad odors, and in preserving fertilizing
matters for the use of crops.
It may be used like plaster, or in the decomposition of organic matters,
where it not only hastens decay, but absorbs and retains the escaping
gases. It will be recollected that _chloride of lime_ is one of the
products of the _lime and salt mixture_.
_Lime_ in combination with _phosphoric acid_ forms the valuable
_phosphate of lime_, of which so large a portion of the ash of grain,
and the bones of animals, is formed. This will be spoken of more at
length under the head of 'phosphoric acid.'
MAGNESIA.
Magnesia is a constituent of vegetable ashes, and is almost always
present in the soil in sufficient quantities. When analysis indicates
that it is needed, it may be applied in the form of _magnesian lime_, or
_refuse epsom salts_, which are composed of sulphuric acid and magnesia
(sulphate of magnesia).
The great care necessary concerning the use of magnesia is, not to apply
too much of it, it being, when in excess, as has been previously
remarked, injurious to the fertility of the soil. Some soils are
hopelessly barren from the fact that they contain too much magnesia.
ACIDS.
SULPHURIC ACID.
[What is sulphuric acid commonly called?
How may it be used?
How does it prevent the escape of ammonia?]
_Sulphuric acid_ is a very important constituent of vegetable ashes,
especially of oats and the root-crops.
It is often deficient in the soil, particularly where potatoes have been
long cultivated. One of the reasons why _plaster_ (sulphate of lime) is
so beneficial to the potato crop is undoubtedly that it supplies it with
sulphuric acid.
Sulphuric acid is commonly known by the name of _oil vitriol_, and may
be purchased for agricultural purposes at a low price. It may be used in
a very dilute form (weakened by mixing it with a large quantity of
water) to the compost heap, where it will change the ammonia to a
sulphate as soon as formed, and thus prevent its loss, as the sulphate
of ammonia is not volatile; and, being soluble in water, is useful to
plants. Some idea of the value of this compound may be formed from the
fact that manufacturers of manures are willing to pay seven cents per
lb., or even more, for sulphate of ammonia, to insure the success of
their fertilizers. Notwithstanding this, many farmers persist in
throwing away hundreds of pounds of _ammonia_ every year, as a tax for
their ignorance (or indolence), while a small tax in _money_--not more
valuable, nor more necessary to their success--for the support of common
schools, and the better education of the young, is too often unwillingly
paid.
[What is the effect of using too much sulphuric acid?]
If a tumbler full of sulphuric acid (costing a few cents), be thrown
into the tank of the compost heap once a month, the benefit to the
manure would be very great.
Where a deficiency of sulphuric acid in the soil is indicated by
analysis, it may be supplied in this way, or by the use of plaster or
refuse epsom salts.
Care is necessary that _too much_ sulphuric acid be not used, as it
would prevent the proper decomposition of manures, and would induce a
growth of sorrel in the soil by making it _sour_.
In many instances, it will be found profitable to use sulphuric acid in
the manufacture of super-phosphate of lime (as directed under the head
of 'phosphoric acid,') thus making it perform the double purpose of
preparing an available form of phosphate, and of supplying sulphur and
sulphuric acid to the plant.
PHOSPHORIC ACID.
[How large a part of the ashes of grain consists of phosphoric
acid?
Of what other substances does it form a leading ingredient?
How many pounds of sulphuric acid are contained in one hundred bushels
of wheat?]
We come now to the consideration of one of the most important of all
subjects connected with agriculture, that is, _phosphoric acid_.
_Phosphoric acid_, forming about one half of the ashes of wheat, rye,
corn, buckwheat, and oats; nearly the same proportion of those of
barley, peas, beans and linseed; an important ingredient of the ashes of
potatoes and turnips; one quarter of the ash of milk and a large
proportion of the bones of animals, often exists in the soil in the
proportion of only about one or two pounds in a thousand. The
cultivation of our whole country has been such, as to take away the
phosphoric acid from the soil without returning it, except in very
minute quantities. Every hundred bushels of wheat sold contains (and
removes permanently from the soil) about _sixty pounds_ of phosphoric
acid. Other grains, as well as the root crops and grasses, remove
likewise a large quantity of it. It has been said by a contemporary
writer, that for each cow kept on a pasture through the summer, there is
carried off in veal, butter and cheese, not less than _fifty_ lbs. of
phosphate of lime (bone-earth) on an average. This would be _one
thousand lbs._ for twenty cows; and it shows clearly why old dairy
pastures become so exhausted of this substance, that they will no longer
produce those nutritious grasses, which are favorable to butter and
cheese-making.
[How much phosphate of lime will twenty cows remove from a
pasture during a summer?
What has this removal of phosphate of lime occasioned?
How have the Genesee and Mohawk valleys been affected by this removal of
phosphoric acid?]
That this removal of the most valuable constituent of the soil, has been
the cause of more exhaustion of farms, and more emigration, in search of
fertile districts, than any other single effect of injudicious farming,
is a fact which multiplied instances most clearly prove.
It is stated that the Genesee and Mohawk valleys, which once produced an
average of _thirty-five_ or _forty bushels_ of wheat, per acre, have
since been reduced in their average production to _twelve and a half_
bushels. Hundreds of similar cases might be stated; and in a large
majority of these, could the cause of the impoverishment be ascertained,
it would be found to be the removal of the phosphoric acid from the
soil.
[How may this devastation be arrested?
Is any soil inexhaustible?
What is usually the best source from which to obtain phosphoric acid?]
The evident tendency of cultivation being to continue this murderous
system, and to prey upon the vital strength of the country, it is
necessary to take such measures as will arrest the outflow of this
valuable material. This can never be fully accomplished until laws shall
be made preventing the wastes of cities and towns. Such laws have
existed for a long time in China, and have doubtlessly been the secret
of the long subsistence and present prosperity of the millions of people
inhabiting that country.
We have, nevertheless, a means of restoring to fertility many of our
worn-out lands, and preserving our fertile fields from so rapid
impoverishment as they are now suffering. Many suppose that soils which
produce good crops, year after year, are inexhaustible, but time will
prove to the contrary. They may possess a sufficiently large stock of
phosphoric acid, and other constituents of plants, to last a long time,
but when that stock becomes so reduced, that there is not enough left
for the uses of full crops, the productive power of the soil will yearly
decrease, until it becomes worthless. It may last a long time, a
century, or even more, but as long as the system is--to _remove every
thing, and return nothing_,--the fate of the most fertile soil is
evident.
The source mentioned, from which to obtain phosphoric acid, is the bones
of animals. These contain large quantities of _phosphate of lime_. They
are the receptacles which collect nearly all of the phosphates in crops,
which are fed to animals, and are not returned in their excrements. For
the grain, etc., sent out of the country, there is no way to be repaid
except by the importation of this material; but, all that is fed to
animals, or to human beings, may, if a proper use be made of their
excrement, and of their bones after death, be returned to the soil. With
the treatment of animal excrements we are already familiar, and we will
now turn our attention to the subject of
BONES.
[Of what do dried bones consist?
What is the organic matter of bones?
The inorganic?
What can you say of the use of whole bones?]
_Bones_ consist, when dried, of about one third organic matter, and two
thirds inorganic matter.
The organic matter consists chiefly of _gelatine_--a compound containing
_nitrogen_.
The inorganic part is chiefly _phosphate of lime_.
Hence, we see that bones are excellent, as both organic and mineral
manure. The organic part, containing nitrogen, forms _ammonia_, and the
inorganic part supplies the much needed _phosphoric acid_ to the soil.
Liebig says that, as a producer of ammonia, 100 lbs. of dry bones are
equivalent to 250 lbs. of human urine.
[How does the value of bone dust compare with that of broken
bones?
What is the reason of the superiority of bone dust?
How is bone-black made?
Of what does it consist?]
Bones are applied to the soil in almost every conceivable form. _Whole
bones_ are often used in very large quantities; their action, however,
is extremely slow, and it is never advisable to use bones in this form.
Ten bushels of bones, finely ground, will produce larger results, during
the current ten years after application, than would ensue from the use
of one hundred bushels merely broken, not because the dust contains more
fertilizing matter than the whole bones, but because that which it does
contain is in a much more available condition. It ferments readily, and
produces ammonia, while the ashy parts are exposed to the action of
roots.
[Should farmers burn bones before using them?
How would you compost bones with ashes?
In what way would you prevent the escape of ammonia?]
_Bone-black._ If bones are burned in retorts, or otherwise protected
from the atmosphere, their organic matter will all be driven off, except
the carbon, which not being supplied with oxygen cannot escape. In this
form bones are called _ivory black_, or _bone-black_. It consists of the
inorganic matter, and the carbon of the bones. The nitrogen having been
expelled it can make no ammonia, and thus far the original value of
bones is reduced by burning; that is, one ton of bones contains more
fertilizing matter before, than after burning; but one ton of bone black
is more valuable than one ton of raw bones, as the carbon is retained in
a good form to act as an absorbent in the soil, while the whole may be
crushed or ground much more easily than before being burned. This means
of pulverizing bones is adopted by manufacturers, who replace the
ammonia in the form of guano, or otherwise; but it is not to be
recommended for the use of farmers, who should not lose the ammonia,
forming a part of bones, more than that of other manure.
_Composting bones with ashes_ is a good means of securing their
decomposition. They should be placed in a water-tight vessel (such as a
cask); first, three or four inches of bones, then the same quantity of
strong unleached wood ashes, continuing these alternate layers until the
cask is full, and keeping them _always wet_. If they become too dry they
will throw off an offensive odor, accompanied by the escape of ammonia,
and consequent loss of value. In about one year, the whole mass of bones
(except, perhaps, those at the top) will be softened, so that they may
be easily crushed, and they are in a good condition for manuring. The
ashes are, in themselves, valuable, and this compost is excellent for
many crops, particularly for Indian corn. A little dilute sulphuric
acid, occasionally sprinkled on the upper part of the matter in the
cask, will prevent the escape of the ammonia.
[What is the effect of boiling bones under pressure?
How is super-phosphate of lime made?
Describe the composition of phosphate of lime, and the chemical changes
which take place in altering it to super-phosphate of lime.]
_Boiling bones under pressure_, whereby their gelatine is dissolved
away, and the inorganic matter left in an available condition, from its
softness, is a very good way of rendering them useful; but, as it
requires, among other things, a steam boiler, it is hardly probable that
it will be largely adopted by farmers of limited means.
Any or all of these methods are good, but bones cannot be used with true
economy, except by changing their inorganic matter into
SUPER-PHOSPHATE OF LIME.
_Super-phosphate of lime_ is made by treating phosphate of lime, or the
ashes of bones, with _sulphuric acid_.
Phosphate of lime, as it exists in bones, consists of one atom of
phosphoric acid and three atoms of lime. It may be represented as
{ Lime
Phosphoric acid { Lime
{ Lime
By adding a proper quantity of sulphuric acid with this, it becomes
_super_-phosphate of lime; that is, the same amount of phosphoric acid,
with a smaller proportion of lime (or a _super_-abundance of phosphoric
acid), the sulphuric acid, taking two atoms of lime away from the
compound, combined with it making sulphate of lime (plaster). The
changes may be thus represented.
{Phosphoric acid} Super-phosphate
Phosphate of lime {Lime } of lime.
{Lime}
{Lime} Sulphate of lime.
Sulphuric acid}
Super-phosphate of lime may be made from whole bones, bone dust,
bone-black, or from the pure ashes of bones.
[How should sulphuric acid be applied to whole bones?
What is the necessity for so large an amount of water?]
The process of making it from whole bones is slow and troublesome, as it
requires a long time for the effect to diffuse itself through the whole
mass of a large bone. When it is made in this way, the bones should be
_dry_, and the acid should be diluted in many times its bulk of water,
and should be applied to the bones (which may be placed in a suitable
cask, with a spiggot at the bottom), in quantities sufficient to cover
them, about once in ten days; and at the end of that time, one half of
the liquid should be drawn off by the spiggot. This liquid is a solution
of super-phosphate of lime, containing sulphate of lime, and may be
applied to the soil in a liquid form, or through the medium of a compost
heap. The object of using so much water is to prevent an incrustation of
sulphate of lime on the surfaces of the bones, this must be removed by
stirring the mass, which allows the next application of acid to act
directly on the phosphate remaining. The amount of acid required is
about 50 or 60 lbs. to each 100 lbs. of bones. The gelatine will remain
after the phosphate is all dissolved, and may be composted with muck, or
plowed under the soil, where it will form ammonia.
[May less water be employed in making super-phosphate from
bone dust or crushed bones?]
_Bone dust_, or _crushed bones_, may be much more easily changed to the
desired condition, as the surface exposed is much greater, and the acid
can act more generally throughout the whole mass. The amount of acid
required is the same as in the other case, but it may be used
_stronger_, two or three times its bulk of water being sufficient, if
the bones are finely ground or crushed--more or less water should be
used according to the fineness of the bones. The time occupied will also
be much less, and the result of the operation will be in better
condition for manure.
Bones may be made fine enough for this operation, either by grinding,
etc., or by boiling under pressure, as previously described; indeed, by
whatever method bones are pulverized, they should always be treated with
sulphuric acid before being applied to the soil, as this will more than
double their value for immediate use.
Bone-black is chiefly used by manufacturers of super-phosphate of lime,
who treat it with acid the same as has been directed above, only that
they grind the black very finely before applying the acid.
[What other forms of bones may be used in making
super-phosphate of lime?
Why is super-phosphate of lime a better fertilizer than phosphate of
lime?
What can you say of the _lasting manures_?]
_Bone ashes_, or bones burned to whiteness, may be similarly treated.
Indeed, in all of the forms of bones here described, the phosphate of
lime remains unaltered, as it is indestructible by heat; the differences
of composition are only in the admixture of organic constituents.
_The reason why super-phosphate of lime is so much better than
phosphate_, may be easily explained. The _phosphate_ is very _slowly_
soluble in water, and consequently furnishes food to plants slowly. A
piece of bone as large as a pea may lie in the soil for years without
being all consumed; consequently, it will be years before its value is
returned, and it pays no interest on its cost while lying there. The
_super-phosphate_ dissolves very _rapidly_ and furnishes food for plants
with equal facility; hence its much greater value as a manure.
It is true that the _phosphate_ is the most _lasting_ manure; but, once
for all, let us caution farmers against considering this a virtue in
mineral manures, or in organic manures either, when used on soils
containing the proper absorbents of ammonia. They are _lasting_, only
in proportion as they are _lazy_. Manures are worthless unless they are
in condition to be immediately used. The farmer who wishes his manures
to _last_ in the soil, and to lose their use, may be justly compared
with the _miser_, who buries his gold and silver in the ground for the
satisfaction of knowing that he owns it. It is an old and a true saying
that "a nimble sixpence is better than a slow shilling."
IMPROVED SUPER-PHOSPHATE OF LIME.
[What are the ingredients of the _improved_ super-phosphate of
lime?]
To show the manner in which super-phosphate of lime is perfected, and
rendered the best manure for general uses, which has yet been made,
containing large quantities of phosphoric acid and a good supply of
ammonia,--hereby covering the two leading deficiencies in a majority of
soils, it may be well to explain the composition of the _improved
super-phosphate of lime_ invented by Prof. Mapes.
This manure consists of the following ingredients in the proportions
named:--
100 lbs. bone-black (phosphate of lime and carbon).
56 " sulphuric acid.
36 " guano.
20 " sulphate of ammonia.
[Explain the uses of these different constituents.
What is nitrogenized phosphate?]
The sulphuric acid has the before-mentioned effect on the bone-black,
and _fixes_ the ammonia of the guano by changing it to a sulphate. The
twenty pounds of sulphate of ammonia added increase the amount, so as to
furnish nitrogen to plants in sufficient quantities to give them energy,
and induce them to take up the super-phosphate of lime in the manure
more readily than would be done, were there not a sufficient supply of
ammonia in the soil.
The addition of the guano, which contains all of the elements of
fertility, and many of them in considerable quantities, renders the
manure of a more general character, and enables it to produce very large
crops of almost any kind, while it assists in fortifying the soil in
what is usually its weakest point--phosphoric acid.
Prof. Mapes has more recently invented a new fertilizer called
nitrogenized super-phosphate of lime, composed of the improved
super-phosphate of lime and blood, dried and ground before mixture, in
equal proportions. This manure, from its highly nitrogenous character,
theoretically surpasses all others, and probably will be found in
practice to have great value; its cost will be rather greater than
guano.
We understand its manufacture will shortly be commenced by a company now
forming for that purpose.
[What should be learned before purchasing amendments for the
soil?
What do you know of silica?]
Many farmers will find it expedient to purchase bones, or bone dust, and
manufacture their own super-phosphate of lime; others will prefer to
purchase the prepared manure. In doing so, it should be obtained of men
of known respectability, as manures are easily adulterated with
worthless matters; and, as their price is so high, that such deception
may occasion great loss.
We would not recommend the application of any artificial manure, without
first obtaining an analysis of the soil, and knowing _to a certainty_
that the manure is needed; still, when no analysis has been procured, it
may be profitable to apply such manures as most generally produce good
results--such as stable manure, night soil, the improved super-phosphate
of lime; or, if this cannot be procured, guano.
NEUTRALS.
SILICA.
_Silica_ (or sand) always exists in the soil in sufficient quantities
for the supply of food for plants; but, as has been often stated in the
preceding pages, not always in the proper condition. This subject has
been so often explained to the student of this book, that it is only
necessary to repeat here, that when the weakness of the straw or stalk
of plants grown on any soil indicates an inability in that soil to
supply the silicates required for strength, not more sand should be
added, but _alkalies_, to combine with the sand already contained in it,
and make _soluble silicates_ which are available to roots.
Sand is often necessary to stiff clays, as a _mechanical_ manure, to
loosen their texture and render them easier of cultivation, and more
favorable to the distribution of roots, and to the circulation of air
and water.
CHLORINE.
[How may chlorine be applied?]
_Chlorine_, a necessary constituent of plants, and often deficient in
the soil (as indicated by analysis), may be applied in the form of salt
(chloride of sodium), or chloride of lime. The former may be dissolved
in the water used to slake lime, and the latter may, with much
advantage, be sprinkled around stables and other places where
fertilizing gases are escaping, and, after being saturated with ammonia,
applied to the soil, thus serving a double purpose.
OXIDE OF IRON.
[How may the protoxide of iron be changed to peroxide?]
Nearly all soils contain sufficient quantities of _oxide of iron_, or
iron rust, so that this substance can hardly be required as a manure.
Some soils, however, contain the _prot_oxide of iron in such quantities
as to be injurious to plants,--see page 86. When this is the case, it is
necessary to plow the soil thoroughly, and use such other mechanical
means as shall render it open to the admission of air. The _prot_oxide
of iron will then take up more oxygen, and become the _per_oxide--which
is not only inoffensive, but is absolutely necessary to fertility.
OXIDE OF MANGANESE.
This can hardly be called an essential constituent of plants, and is
never taken into consideration in manuring lands.
VARIOUS OTHER MINERAL MANURES.
LEACHED ASHES.
[Why are leached ashes inferior to those that have not been
leached?
On what do the benefits of leached ashes depend?
Can these ingredients be more cheaply obtained in another form?
Why do unleached ashes, applied in the spring, sometimes cause grain to
lodge?]
Among the mineral manures which have not yet been mentioned--not coming
strictly under any of the preceding heads, is the one known as _leached
ashes_.
These are not without their benefits, though worth much less than
unleached ashes, which, besides the constituents of those which have
been leached, contain much potash, soda, etc.
Farmers have generally overrated the value of leached ashes, because
they contain small quantities of available phosphate of lime, and
soluble silicates, in which most old soils are deficient. While we
witness the good results ensuing from their application, we should not
forget that the fertilizing ingredients of _thirty bushels_ of these
ashes may be bought in a more convenient form for _ten_ or _fifteen
cents_, or for less than the cost of spreading the ashes on the soil. In
many parts of Long Island farmers pay as much as eight or ten cents per
bushel for this manure, and thousands of loads of leached ashes are
taken to this locality from the river counties of New York, and even
from the State of Maine, and are sold for many times their value,
producing an effect which could be as well and much more cheaply
obtained by the use of small quantities of super-phosphate of lime and
potash.
These ashes often contain a little charcoal (resulting from the
imperfect combustion of the wood), which acts as an absorbent of
ammonia.
It is sometimes observed that _unleached_ ashes, when applied in the
spring, cause grain to lodge. When this is the case, as it seldom is, it
may be inferred that the potash which they contain causes so rapid a
growth, that the soil is not able to supply silicates as fast as they
are required by the plants, but after the first year, the potash will
have united with the silica in the soil, and overcome the difficulty.
OLD MORTAR.
[What are the most fertilizing ingredients of old mortar?]
_Old mortar_ is a valuable manure, because it contains nitrate of potash
and other compounds of nitric acid with alkalies.
These are slowly formed in the mortar by the changing of the nitrogen of
the hair (in the mortar) into nitric acid, and the union of this with
the small quantities of _potash_, or with the _lime_ of the plaster.
Nitrogen, presented in other forms, as ammonia, for instance, may be
transformed into nitric acid, by uniting with the oxygen of the air, and
this nitric acid combines immediately with the alkalies of the
mortar.[AI]
The lime contained in the mortar may be useful in the soil for the many
purposes accomplished by other lime.
GAS HOUSE LIME.
[How may gas-house lime be prepared for use?
Why should it not be used fresh, from the gas house?
On what do its fertilizing properties depend?
What use may be made of its offensive odor?]
_The refuse lime of gas works_, where it can be cheaply obtained, may be
advantageously used as a manure. It consists, chiefly, of various
compounds of sulphur and lime. It should be composted with earth or
refuse matter, so as to expose it to the action of air. It should never
be used fresh from the gas house. In a few months the sulphur will have
united with the oxygen of the air, and become sulphuric acid, which
unites with the lime and makes sulphate of lime (plaster), which form it
must assume, before it is of much value. Having been used to purify gas
made from coal, it contains a small quantity of ammonia, which adds to
its value. It is considered a profitable manure in England, at the price
there paid for it (forty cents a cartload), and, if of good quality, it
may be worth double that sum, especially for soils deficient in plaster,
or for such crops as are much benefited by plaster. Its price must, of
course, be regulated somewhat by the price of lime, which constitutes a
large proportion of its fertilizing parts. The offensive odor of this
compound renders it a good protection against many insects.
The refuse _liquor of gas works_ contains enough ammonia to make it a
valuable manure.
SOAPERS' LEY AND BLEACHERS' LEY.
[What use may be made of the refuse ley of soap-makers and
bleachers?
What peculiar qualities does soapers' ley possess?]
The refuse ley of soap factories and bleaching establishments contains
greater or less quantities of soluble silicates and alkalies (especially
soda and potash), and is a good addition to the tank of the compost
heap, or it may be used directly as a liquid application to the soil.
The soapers' ley, especially, will be found a good manure for lands on
which grain lodges.
Much of the benefit of this manure arises from the soluble silicates it
contains, while its nitrogenous matter,[AJ] obtained from those parts of
the fatty matters which cannot be converted into soap, and consequently
remains in this solution, forms a valuable addition. Heaps of soil
saturated with this liquid in autumn, and subjected to the freezings of
winter, form an admirable manure for spring use. Mr. Crane, near Newark
(N. J.), has long used a mixture of spent ley and stable manure, applied
in the fall to trenches plowed in the soil, and has been most successful
in obtaining large crops.
IRRIGATION.
[On what does the benefit arising from irrigation chiefly
depend?
What kind of water is best for irrigation?
How do under-drains increase the benefits of irrigation?]
_Irrigation_ does not come strictly under the head of inorganic manures,
as it often supplies ammonia to the soil. Its chief value, however, in
most cases, must depend on the amount of mineral matter which it
furnishes.
The word "irrigation" means simply _watering_. In many districts water
is in various ways made to overflow the land, and is removed when
necessary for the purposes of cultivation. All river and spring water
contains some impurities, many of which are beneficial to vegetation.
These are derived from the earth over, or through which, the water has
passed, and ammonia absorbed from the atmosphere. When water is made to
cover the earth, especially if its rapid motion be arrested, much of
this fertilizing matter settles, and is deposited on the soil. The water
which sinks into the soil carries its impurities to be retained for the
uses of plants. When, by the aid of under-drains, or in open soils, the
water passes _through_ the soil, its impurities are arrested, and become
available in vegetable growth. It is, of course, impossible to say
exactly what kind of mineral matter is supplied by water, as that
depends on the kind of rock or soil from which the impurities are
derived; but, whatever it may be, it is generally soluble and ready for
immediate use by plants.
[What is the difference between water which only runs over the
surface of the earth, and that which runs out of the earth?
Why should strong currents of water not be allowed to traverse the
soil?]
Water which has run over the surface of the earth contains both ammonia
and mineral matter, while that which has arisen out of the earth,
contains usually only mineral matter. The direct use of the water of
irrigation as a solvent for the mineral ingredients of the soil, is one
of its main benefits.
To describe the many modes of irrigation would be too long a task for
our limited space. It may be applied in any way in which it is possible
to cover the land with water, at stated times. Care is necessary,
however, that it do not wash more fertilizing matter from the soil than
it deposits on it, as would often be the case, if a strong current of
water were run over it. Brooks may be dammed up, and thus made to cover
a large quantity of land. In such a case the rapid current would be
destroyed, and the fertilizing matter would settle; but, if the course
of the brook were turned, so that it would run in a current over any
part of the soil, it might carry away more than it deposited, and thus
prove injurious. Small streams turned on to land, from the washing of
roads, or from elevated springs, are good means of irrigation, and
produce increased fertility, except where the soil is of such a
character as to prevent the water from passing away, in which case it
should be under-drained.
Irrigation was one of the oldest means of fertility ever used by man,
and still continues in great favor wherever its effects have been
witnessed.
MIXING SOILS.
[How are soils improved by mixing?]
The _mixing of soils_ is often all that is necessary to render them
fertile, and to improve their _mechanical_ condition. For instance,
soils deficient in potash, or any other constituent, may have that
deficiency supplied, by mixing with them soil containing this
constituent in excess.
It is very frequently the case, that such means of improvement are
easily availed of. While these chemical effects are being produced,
there may be an equal improvement in the mechanical character of the
soil. Thus stiff clay soils are rendered lighter, and more easily
workable, by an admixture of sand, while light blowy sands are
compacted, and made more retentive of manure, by a dressing of clay or
of muck.
[Why may the same effect sometimes be produced by deep
plowing?
What is absolutely necessary to economical manuring?]
Of course, this cannot be depended on as a sure means of chemical
improvement, unless the soils are previously analyzed, so as to know
their requirements; but, in a majority of cases, the soil will be
benefited, by mixing with it soil of a different character. It is not
always necessary to go to other locations to procure the soil to be
applied, as the subsoil is often very different from the surface soil,
and simple deep plowing will suffice, in such cases, to produce the
required admixture, by bringing up the earth from below to mingle it
with that of a different character at the surface.
* * * * *
In the foregoing remarks on the subject of mineral manures, the writer
has endeavored to point out such a course as would produce the "greatest
good to the greatest number," and, consequently, has neglected much
which might discourage the farmer with the idea, that the whole system
of scientific agriculture is too expensive for his adoption. Still,
while he has confined his remarks to the more simple improvements on the
present system of management, he would say, briefly, that _no manuring
can be strictly economical that is not based on an analysis of the soil,
and a knowledge of the best means of overcoming the deficiencies
indicated, together with the most scrupulous care of every ounce of
evaporating or soluble manure_.
FOOTNOTES:
[AG] Marl is earth containing lime, but its use is not to be recommended
in this country, except where it can be obtained at little cost, as the
expenses of carting the _earth_ would often be more than the value of
the _lime_.
[AH] The straw producing the grain and the turnip and potato tops
contain more lime than the grain and roots.
[AI] See Working Farmer, vol. 2, p. 278.
[AJ] Glycerine, etc.