COMPOSITION AND PROPERTIES OF ANIMAL MANURES.
Manures of animal origin are generally characterized by the large
quantity of nitrogen they contain, which causes them to undergo
decomposition with great rapidity, and to yield the greater part of
their valuable matters to the crop to which they are applied.
_Guano._--By far the most important animal manure is guano, which is
composed of the solid excrements of carnivorous birds in a more or less
completely decomposed state, and is accumulated in immense quantities on
the coasts of South America and other tropical countries. It has been
used as a manure in Peru from time immemorial, but the accounts given by
the older travellers of its marvellous effects were considered to be
fabulous, until Humboldt, from personal observation, confirmed their
statements. It was first imported into this country in 1840, in which
year a few barrels of it were brought home; and from that time its
importation rapidly increased. Soon after large deposits of it were
found in Ichaboe; and it has since been brought from many other
localities. The quantity of guanos of all kinds imported into this
country and retained for home consumption now exceeds 240,000 tons a
year.
The value of guano differs greatly according to the extent to which its
decomposition has gone, and this is chiefly dependent on the climate of
the locality from which it is obtained. When deposited in the rainless
districts of Peru it still retains some of the uric acid and the greater
part of the ammonia naturally existing in it, and the quantity which has
escaped by decomposition is unimportant. But that obtained from other
districts has suffered a more or less complete decomposition according
to the humidity of the climate, which reduces the quantity of organic
matters and ammonia, until, in some varieties, they are so small as to
be of little importance. The following are minute analyses of three
specimens of Peruvian guano, shewing all the different constituents it
contains, and the amount of difference which may exist:--
I. II. III.
Urate of ammonia 10.70 9.0 3.24
Oxalate of ammonia 12.38 10.6 13.35
Oxalate of lime 5.44 7.0 16.36
Phosphate of ammonia 19.25 6.0 6.45
Phosphate of magnesia and ammonia ... 2.6 4.20
Sulphate of potash 4.50 5.5 4.23
Sulphate of soda 1.95 3.8 1.12
Sulphate of ammonia 3.36 ... ...
Muriate of ammonia 4.81 4.2 6.50
Phosphate of soda ... ... 5.29
Chloride of sodium ... ... 0.10
Phosphate of lime 15.56 14.3 9.94
Carbonate of lime 1.80 ... ...
Sand and alumina 1.59 4.7 5.80
Water 9.14 }
} 32.3 23.42
Undetermined humus-like organic} 10.00 }
matters } }
------ ----- ------
100.48 100.0 100.00
These analyses illustrate two points--_first_, that in some samples the
decomposition has advanced to a greater extent than in others; for we
observe that the quantity of uric acid, or rather of urate of ammonia,
is greatly less in the last analysis than in the other two, and much
smaller than in the fresh dung, which contains from 50 to 70 per cent of
uric acid; and _secondly_, that guano is rich in all the constituents of
the plant, but especially in ammonia, the best form in which nitrogen
can be supplied, in uric acid which by decomposition yields ammonia, and
in phosphoric acid. But such analyses are too elaborate for ordinary
purposes, and much less convenient for comparison and for estimating the
value of the guano than the shorter analysis commonly in use, which
gives the water, the loss by ignition (that is, the sum of the organic
matters and ammoniacal salts), the phosphates, the alkaline salts, and
the quantity of phosphoric acid contained in them, and existing there in
a state similar to that in which it is found in the soluble phosphates
of a superphosphate. In addition to these, the quantities of sand and
other less valuable ingredients are also stated.
In the subjoined tables the composition of a great variety of different
kinds of guano is given. Most of these are averages deduced from a
considerable number of analyses of good samples. Those of some kinds of
guano, such as Peruvian, which present a considerable amount of
uniformity, afford a sufficiently accurate idea of the general
composition of the variety, but in other cases they are of less value,
because the imports of different seasons, and even of different cargoes,
differ so greatly in composition that no proper average can be made.
Several of these varieties are already exhausted, the importation of
others has ceased, and new varieties are constantly being introduced.
_Table showing the Average Composition of different varieties of Guano._
-------------------+--------+-------+-------------+---------------------------+
|Angamos.|Peru- | ICHABOE. |Bolivian or Upper |
| | vian. | |Peruvian. |
| | +-------------+------+-----------+--------+
| | |Old. |New. |Old. |Government.|Inferior|
-------------------+--------+-------+------+------+------+-----------+--------+
Water | 12.36 | 13.73 |24.21 |18.89 | 12.55| 16.44 | 14.15 |
Organic matter }| | | | | | | |
and ammoniacal }| 59.92 | 53.16 |39.30 |32.49 | 35.89| 12.28 | 26.14 |
salts }| | | | | | | |
Phosphates | 17.01 | 23.48 |30.00 |19.63 | 27.63| 56.09 | 23.13 |
Sulphate of lime | ... | ... | ... | ... | ... | ... | 9.65 |
Carbonate of lime | ... | ... | ... | ... | ... | ... | 12.87 |
Alkaline salts | 7.20 | 7.97 | 4.19 | 8.82 | 15.29| 11.33 | 5.97 |
Sand | 3.51 | 1.66 | 2.30 | 6.72 | 8.64| 2.81 | 8.09 |
+--------+-------+------+------+------+-----------+--------+
| 100.00 |100.00 |100.00|100.00|100.00|100.00 |100.00 |
Ammonia | 21.10 | 17.00 | 8.50| 10.42| 8.99| 2.57 | 3.26 |
Phosphoric }| | | | | | | |
acid in alkaline}| 1.20 | 2.50 | ... | ... | ... | 3.11 | ... |
salts }| | | | | | | |
-------------------+--------+-------+------+------+------+-----------+--------+
-------------------+---------+-------+--------+-----------+-------------+
| | | | | |
|Pacquico.|Latham |Saldanha|Australian.|Kooriamooria.|
| |Island.|Bay. | | |
| | | | | |
-------------------+---------+-------+--------+-----------+-------------+
Water | 8.38 | 24.96 | 21.03 | 13.20 | 8.91 |
Organic matter }| | | | | |
and ammoniacal }| 23.10 | 10.96 | 14.93 | 13.77 | 7.72 |
salts }| | | | | |
Phosphates | 32.36 | 54.47 | 56.40 | 44.47 | 44.15 |
Sulphate of lime | 2.92 | 2.82 | ... | 4.55 | 3.19 |
Carbonate of lime | ... | 2.20 | ... | 8.82 | 3.37 |
Alkaline salts | 25.43 | 4.06 | 6.10 | 7.34 | 11.23 |
Sand | 7.81 | 0.51 | 1.54 | 7.85 | 21.43 |
+---------+-------+--------+-----------+-------------+
|100.00 |100.00 |100.00 |100.00 |100.00 |
Ammonia | 6.58 | 1.26 | 1.62 | 1.01 | 0.42 |
Phosphoric }| | | | | |
acid in alkaline}| 3.50 | ... | ... | ... | ... |
salts }| | | | | |
-------------------+---------+-------+--------+-----------+-------------+
-------------------+-----------+--------+--------+
| | | |
|Patagonian.|Chilian.|Mexican.|
| | | |
| | | |
-------------------+-----------+--------+--------+
Water | 20.61 | 14.89 | 18.80 |
Organic matter }| | | |
and ammoniacal }| 19.72 | 16.81 | 12.88 |
salts }| | | |
Phosphates | 30.66 | 36.90 | 18.38 |
Sulphate of lime | 1.30 | ... | 27.79 |
Carbonate of lime | 3.06 | 10.28 | ... |
Alkaline salts | 7.01 | 6.84 | 16.95 |
Sand | 17.04 | 14.26 | 5.20 |
+-----------+--------+--------+
|100.00 |100.00 |100.00 |
Ammonia | 2.69 | 1.42 | 0.42 |
Phosphoric }| | | |
acid in alkaline}| 3.00 | ... | ... |
salts }| | | |
-------------------+-----------+--------+--------+
_Table shewing the Composition of some of the less common varieties of
Guano._
NOTE.--The numbers in this Table are mostly derived only from a single
analysis and have no value as determining the average composition of
these Guanos, but they serve to give a general idea of their value.
-------------------+--------+---------+---------+-----------+------------+
| Sea | Indian. | Holme's | Ascension | Possession |
| Bear | | Bird | Island. | Island. |
| Bay. | | Island. | | |
-------------------+--------+---------+---------+-----------+------------+
Water | 30.82 | 23.62 | 25.00 | 15.97 | 10.92 |
Organic matter }| | | | | |
and ammoniacal }| 31.78 | 60.05 | 32.10 | 23.15 | 15.42 |
salts }| | | | | |
Phosphates | 24.33 | 7.18 | 27.36 | 32.54 | 46.41 |
Sulphate of lime | 3.84 | ... | ... | ... | 7.46 |
Carbonate of lime | 0.58 | 2.79 | ... | ... | ... |
Alkaline salts | 7.38 | 5.58 | 8.82 | 15.92 | 6.15 |
Sand | 1.27 | 0.78 | 6.72 | 12.42 | 13.64 |
+--------+---------+---------+-----------+------------+
|100.00 | 100.00 | 100.00 | 100.00 | 100.00 |
| | | | | |
Ammonia | 10.45 | 10.27 | 7.75 | 6.06 | 1.34 |
Phosphoric }| | | | | |
acid in alkaline}| ... | ... | ... | 1.82 | ... |
salts }| | | | | |
-------------------+--------+---------+---------+-----------+------------+
-------------------+-------+---------+---------+---------+
| Algoa | New | Bird's | Leone |
| Bay. | Island. | Island. | Island. |
-------------------+-------+---------+---------+---------+
Water | 30.55 | 28.78 | 16.52 | 23.65 |
Organic matter }| | | | |
and ammoniacal }| 6.85 | 13.78 | 14.84 | 4.27 |
salts }| | | | |
Phosphates | 21.24 | 22.46 | 25.21 | 13.58 |
Sulphate of lime | 36.42 | ... | 40.47 | 29.95 |
Carbonate of lime | ... | 13.78 | ... | ... |
Alkaline salts | 3.32 | 12.62 | 1.16 | 5.40 |
Sand | 1.62 | 11.58 | 1.80 | 23.15 |
+-------+---------+---------+---------+
|100.00 | 100.00 | 100.00 | 100.00 |
| | | | |
Ammonia | 0.54 | 0.84 | 1.26 | 0.67 |
Phosphoric }| | | | |
acid in alkaline}| ... | ... | ... | ... |
salts }| | | | |
-------------------+-------+---------+---------+---------+
On examining the tables given above, it is obvious that guanos may be
divided into two classes, the one characterized by the abundance of
ammonia, the other by that of phosphates; and which, for convenience
sake, may be called ammoniacal and phosphatic guanos. Peruvian and
Angamos are characteristic of the former, and Saldanha Bay and Bolivian
of the latter class. The value of these two classes of guano differs
materially, and they are also applicable under different circumstances,
but to these points reference will afterwards be made.
Very special precautions are necessary on the part of the farmer in
order to insure his obtaining a guano which is not adulterated, and of
good quality if genuine. In the case of Peruvian guano, which is
tolerably uniform in its qualities, it is possible to form some opinion
by careful examination, and the following points ought to be attended
to:
1st, The guano should be light coloured. If it is dark, the chances are
that it has been damaged by water.
2d, It should be dry, and when a handful is well squeezed together it
should cohere very slightly.
3d, It should not have too powerful an ammoniacal odour.
4th, It should contain lumps, which, when broken, appear of a paler
colour than the powdery part of the sample.
5th, When rubbed between the fingers it should not be gritty.
6th, A bushel of the guano should not weigh more than from 56 to 60 lbs.
These characters must not, however, be too implicitly relied on, for
they are all imitated with wonderful ingenuity by the skilful
adulterator, and they are applicable only to Peruvian guano; the others
being so variable that no general rules can be given for determining
whether they are genuine. Neither are they so precise as to enable us to
give any opinion regarding the relative values of several samples where
all are genuine. The only way in which adulteration can with certainty
be detected, and the value of different guanos be determined, is by
analysis, and the importance of this can easily be illustrated.
In the table above, the _average_ composition of the different guanos is
given; but in order to shew how much individual cargos may differ from
the mean, we give here analyses of samples of the highest and lowest
quality of the genuine guanos of most importance:
+-------------------+-------------------+------------------+------------------+
| | Angamos. | Peruvian. | Bolivian. |
| +---------+---------+---------+--------+---------+--------+
| |Highest. |Lowest. |Highest. |Lowest. |Highest. |Lowest. |
| +---------+---------+---------+--------+---------+--------+
| Water | 12.60 | 7.09 | 10.37 | 21.49 | 11.53 | 16.20 |
| Organic matter } | | | | | | |
| and ammoniacal } | 65.62 | 50.83 | 55.73 | 46.26 | 11.17 | 12.86 |
| salts } | | | | | | |
| Phosphates | 10.83 | 8.70 | 25.20 | 18.93 | 62.99 | 52.95 |
| Alkaline salts | 7.50 | 16.30 | 7.50 | 10.64 | 9.93 | 13.83 |
| Sand | 3.45 | 17.08 | 1.20 | 2.68 | 4.38 | 4.16 |
| +---------+---------+---------+--------+---------+--------+
| | 100.00 | 100.00 | 100.00 |100.00 | 100.00 | 100.00 |
| | | | | | | |
| Ammonia | 25.33 | 17.15 | 18.95 | 14.65 | 1.89 | 2.23 |
+-------------------+---------+---------+---------+--------+---------+--------+
The differences are here exceedingly large; and when the values of the
two Peruvian guanos are calculated according to the method to be
afterwards described, it appears that the highest exceeds the lowest in
value by nearly L3 per ton. Of course, this is an extreme case, but it
is no uncommon occurrence to find a difference of L1 or even L2 per ton
between the values of cargos of Peruvian guano, which are sold at the
same price.
The adulteration of guano is carried on to a very large extent; and
though perhaps not quite so extensively now as it was some years since,
it is only kept in check by the utmost vigilance on the part of the
purchaser. The chief adulterations are a sort of yellow loam very
similar in appearance to guano, sand, gypsum, common salt, and
occasionally also ground coprolites and inferior guano. These substances
are rarely used singly, but are commonly mixed in such proportions as
most closely to imitate the colour and general appearance of the genuine
article. The extent to which the adulteration is carried may be judged
of from the following analyses taken at random from those of a large
number of guanos, all of which were sold as first-class Peruvian.
Water 12.85 15.19 12.06 27.86 6.32
Organic matter and }
ammoniacal salts } 26.84 44.31 34.14 30.41 27.42
Phosphates 15.54 20.95 22.08 22.17 33.61
Sulphate of lime ... ... 11.08 ... 22.11
Alkaline salts 6.07 9.40 12.81 7.92 22.50
Sand 38.70 10.15 7.83 1.64 10.15
------ ------ ------ ------ ------
100.00 100.00 100.00 100.00 100.00
Ammonia 9.34 13.90 9.77 8.64 9.76
In all those cases a very large depreciation in the value has taken
place, and several of them are worth considerably less than half the
price of the genuine guano, while they are generally offered for sale at
about L1 under the usual price. The adulteration is chiefly practised in
London, and cases occasionally occur which can be traced to Liverpool
and other places; but it always takes place in the large towns, because
it is only there that facilities exist for obtaining the necessary
materials and carrying it out without exciting suspicion. The
sophisticated article then passes into the hands of the small country
dealers, to whom it is sold with the assurance that it is genuine, and
analysis quite unnecessary. In other instances, adulterated and inferior
guanos are sold by the analysis of a genuine sample, and sometimes an
analysis is made to do duty for many successive cargos of a guano which,
though all obtained from one deposit, may differ excessively in
composition. In order to insure obtaining a genuine guano, it is above
all things important to deal only with a person of established
character, who will generally, for his own sake, satisfy himself that
the article he vends is genuine and of good quality; and it is always
important that the buyer should examine the analysis, and in all cases
where there is the slightest doubt, should ascertain that the bulk sent
corresponds with it. In the case of a Peruvian guano, a complete
analysis is not necessary for this purpose; but an experienced chemist,
by the application of a few tests, can readily ascertain whether the
sample is genuine. Where the difference in value between different
samples is required, a complete analysis is necessary, and this is
indispensable in the case of the inferior guanos. Many of these are
obtained from deposits of limited extent, and in loading it considerable
quantities of the subjacent soil are taken up, so that very great
differences may exist even in different parts of the same cargo. Nor
must it be forgotten that, except in the case of Peruvian, the name is
no guarantee for the quality of the guano, even if genuine. Peruvian
guano is all obtained from the same deposits, those of the Chincha
Islands, but the guanos which are brought into the market under the name
of Patagonian, Chilian, etc., are obtained from a great variety of
deposits scattered along the coasts of these countries, sometimes at a
distance of several hundred miles from each other, and which have been
accumulated under totally different circumstances. In illustration of
this, it is only necessary to refer to the subjoined analysis of
samples, all of which I believe to be genuine as imported, and which
were sold under the name of Upper Peruvian Guano.
I. II. III.
Water 7.80 6.65 8.85
Organic matter and ammoniacal salts 10.85 19.16 10.20
Phosphates 67.00 20.41 17.10
Carbonate of lime ... 21.15 ...
Alkaline salts 11.10 5.31 61.30
Sand 3.25 27.32 2.55
------ ------ ------
100.00 100.00 100.00
Ammonia 2.29 5.73 1.48
Phosphoric acid in the alkaline salts 2.24 ... 1.70
Equal to phosphate of lime 4.89 ... 3.70
With the exception of Peruvian, the supply of _good_ guanos of uniform
composition is by no means large, and phosphatic guanos of good quality
are now especially rare. The Saldanha Bay, and other similar deposits,
have been exhausted, and few guanos of equally good quality have been
lately discovered. There is no doubt, however, that such guanos are very
useful, and if obtained in large quantity, and of uniform composition,
would be used to a much larger extent than they at present are.
The value and use of guano are now so well understood, that it is
scarcely necessary to enlarge on the mode of its application. Peruvian
guano owes its chief value to its ammonia and phosphates, but it also
contains potash, soda, and all the other constituents of plants in small
quantity, although in a readily available condition, as is seen in the
detailed analysis given in page 205.
In other guanos which have undergone more complete decomposition, and
from which the soluble matters have been more or less completely
exhausted by rain, the alkaline salts, or at least the potash they
originally contained, have almost entirely disappeared. Hence an
important difference between Peruvian guano and most other varieties.
The former can be used as a complete substitute for farm-yard manure,
and excellent crops of turnips and potatoes can be raised by means of it
alone, and at a less cost than with ordinary dung. But though this may
be done, and in many cases is attended with great economic advantages,
it is a practice that cannot be recommended for general use, because the
quantity of valuable matters contained in the usual application of guano
is much smaller than in farm-yard manure, and the probability is that it
would not, if used alone during a succession of years, be sufficient to
maintain the soil permanently in a high state of fertility. Five cwt. of
Peruvian guano, which is a liberal application per acre, contains about
95 lbs. of ammonia, and 130 of phosphates, while 20 tons of good
farm-yard manure contain 312 of ammonia, and about the same quantity of
phosphates, and when the other constituents, such as potash and soda,
are compared with those in guano, the difference is still more striking.
On the other hand, guano is a rapidly acting manure; its constituents
are in a condition in which they are more immediately accessible by the
plant, and its immediate effect is far more marked, as it is chiefly
expended on the crop to which it is applied. It has indeed been alleged
that it produces no effects on the subsequent crops, but this opinion
can scarcely be considered as well founded. In no case does the crop
raised by means of it contain the whole of the ammonia or phosphates
present in the manure, and the unappropriated quantity, though it may,
and probably does, escape from the lighter soils, must be retained and
preserved for the use of subsequent crops by heavy and retentive clay
soils. The general inference is, that though guano may at an emergency
be used as an entire substitute for farm-yard manure, the practice is
one to be generally avoided. When, however, as occasionally happens
after a long continued use of farm-yard manure, organic matters have
accumulated in the soil, and passed into an inert condition, then
Peruvian guano may be used alone with very great advantage. In all cases
the rapidity of the action of guano makes it an important auxiliary of
farm-yard manure, and it is in this way that it may be most
advantageously employed. Experience has shewn that one-half the
farm-yard manure may be replaced by guano with the production of a
larger crop than by the former alone in its full quantity. The
proportion of guano usually employed is from three to five cwt., and it
is alleged that a much larger quantity produces prejudicial effects on
the subsequent crops, although it is not very easy to see on what this
depends.
The variety of guano to be selected must depend to a great extent on the
use to which it is to be put. Peruvian guano is most advantageously
applied as a top-dressing to young corn and particularly to oats. For
the turnip, the ammoniacal guanos were formerly preferred, and on strong
soils, under good cultivation, their effects are excellent, but on
light soils they are less applicable, their soluble salts being more
rapidly washed out, and their effects lost, and in these cases they are
surpassed by the phosphatic guanos.
No definite rules can be given for determining the soils on which these
different varieties are most applicable, but each individual must
determine by experiment that which best suits his own farm; and the
inquiry is of much importance to him, as, of course, if the phosphatic
guanos will answer as well as the ammoniacal, there is a large saving in
the cost of the manure. A very excellent practice is to employ a mixture
of equal parts of the two sorts of guano.
_Pigeons' Dung._--The dung of all birds, which more or less closely
resembles guano, may be employed with much advantage as a manure, but
that of the pigeon and the common fowl are the only ones which can be
got in quantity. Pigeons' dung, according to Boussingault, contains 8.3
per cent of nitrogen, equivalent to 10.0 of ammonia. Its value,
therefore, will be more than half that of guano, but it varies greatly,
and a sample imported from Egypt into this country, and analysed by
Professor Johnston, contained only 5.4 per cent of ammonia. Hens' dung
has not been accurately analysed, but its value must be about the same
as pigeons'.
_Urate and Sulphated Urine._--We have already discussed the urine of
animals, in reference to farm-yard manure. But human urine, the
composition of which was then stated, is of much higher value than that
of the lower animals, and many attempts have been made to preserve and
convert it into a dry manure. Urate is prepared by adding gypsum to
urine, and collecting and drying the precipitate produced. It contains a
considerable quantity of the phosphoric acid of the urine, but very
little of its ammonia; and as the principal value of urine depends on
the latter, it is necessarily a very inefficient method of turning it to
account. A better method has been proposed by Dr. Stenhouse, who adds
lime-water to the urine, and collects the precipitate, which, when dried
in the air, contains 1.91 per cent of nitrogen, and about 41 per cent of
phosphates. This method is subject to the same objection as that by
which urate is made, namely, that the greater part of the ammonia is not
precipitated. This might probably be got over to some extent by the
addition of sulphate of magnesia, or, still better, of chloride of
magnesium, which would throw down the phosphate of magnesia and ammonia.
By much the best mode of employing urine is in the form of sulphated
urine, which is made by adding to it a sufficient quantity of sulphuric
acid to neutralize its ammonia, and evaporating to dryness. In this form
all the valuable constituents are retained, and excellent results are
obtained from it. Its effects, though mainly attributable to its
ammonia, are also in part dependent on the phosphates and alkaline salts
which it contains; and it is therefore capable of supplying to the plant
a larger number of its constituents than the animal matters already
mentioned.
_Night-Soil and Poudrette._--The value of night-soil, which is well
known, depends partly on the urine, and partly on the faeces of which it
is formed. Its disagreeable odour has prevented its general use, and
various methods have been contrived both for deodorising and converting
it into a solid and portable form. The same difficulties which beset the
conversion of urine into the solid form occur here, and in most of the
methods employed the loss of ammonia is great. It is sometimes mixed
with lime or gypsum, and dried with heat, and sometimes with animal
charcoal or peat charcoal. The manufacture of a manure from night-soil,
called "poudrette," has long been practised in the neighbourhood of
Paris and other continental towns. The process employed at Montfaucon
and at Bondy is very simple. The contents of the cesspools are conveyed
to the work in large barrels, which are then emptied into tanks capable
of containing the accumulation of several months. When filled they are
allowed to stand for some time, during which the smell diminishes and
the contents become nearly dry. The residue is then dug out and mixed
with ashes, dry loam, charcoal powder, peat, peat-charcoal, saw-dust,
and other matters, so as to deodorize it, and render it sufficiently dry
for transport. Its general composition may be judged of from the
subjoined analyses of samples from different places:--
Montfaucon. Bondy. Dresden. American.
Water 28.00 13.60 19.50 39.97
Organic matters 29.00 24.10 20.80 20.57
Phosphates 7.65 4.96 5.40 1.88
Carbonates of lime and }
Magnesia, alkaline } 7.35 14.14 11.30 7.63
salts, etc. }
Sand 28.00 43.20 43.00 29.95
------ ------ ------ ------
100.00 100.00 100.00 100.00
Ammonia 1.54 1.98 2.60 1.23
These analyses shew sufficiently the extent to which the animal matters
have been mixed with valueless driers, the second and third samples
containing considerably more than half their weight of worthless
matters.
_Hair, Skin, and Horn._--The refuse of manufactories in which these
substances are employed, are frequently used as manures. They are highly
nitrogenous substances, and owe their entire value to the nitrogen they
contain, their inorganic constituents being in too small quantity to be
of any importance, wool and hair having only 2 per cent, and horn 0.7
per cent of ash. In the pure and dry state, and after subtraction of the
ash, their composition is,--
Skin. Human hair. Wool. Horn.
Carbon 50.99 50.65 50.65 51.99
Hydrogen 7.07 6.36 7.03 6.72
Nitrogen 18.72 17.14 17.71 17.28
Oxygen 23.22 20.85 } 24.61 24.01
Sulphur ... 5.00 }
------ ------ ------ ------
100.00 100.00 100.00 100.00
It rarely if ever happens, however, that the refuse offered for sale as
a manure is pure. It always contains water, sand, and other foreign
matters. Woollen rags are mixed with cotton which has no manurial value,
and the skin refuse from tan-works contains much lime. Due allowance
must therefore be made for such impurities which are sometimes present
in very large quantity.
Refuse horse hair generally contains 11 or 12 per cent of nitrogen.
Woollen rags of good quality contain 12.7 per cent of nitrogen; woollen
cuttings about 14; and what is called shoddy only 5.5 per cent. Horn
shavings are extremely variable in their amount of nitrogen; when pure,
they sometimes contain as much as 12.5 per cent, but a great deal of the
horn shavings from comb manufactories, etc., contain much sand and bone
dust, by which their percentage of nitrogen is greatly diminished, and
it sometimes does not exceed 5 or 6 per cent.
All these substances are highly valuable as manures, but it must be
borne in mind that they undergo decomposition very slowly in the soil,
and hence are chiefly applicable to slow growing crops, and to those
which require a strong soil. Woollen rags have been largely employed as
a manure for hops, and are believed to surpass every other substance for
that crop. As a manure applicable to the ordinary purposes of the farm
they have scarcely met with that attention which they deserve, probably
because their first action is slow and the farmer is more accustomed to
look to immediate than to future results; but they possess the important
qualification of adding permanently to the fertility of the soil.
_Blood_ is a most valuable manure, but it is not much employed in this
country, at least in the neighbourhood of large towns, as there is a
demand for it for other purposes, and it can rarely be obtained by the
farmer in large quantity, and at a sufficiently low price. In its
natural state it contains about 3 per cent of nitrogen, and after being
dried up, the residue contains about 15 per cent. It is best used in the
form of a compost with peat or mould, and this forms an excellent manure
for turnips, and is also advantageously applied as a top-dressing to
wheat.
_Flesh._--The flesh of all animals is useful as a manure, and is
especially distinguished by the rapidity with which it undergoes
decomposition, and yields up its valuable matters to the plant. It is
rarely employed in its natural state, but horse flesh was at one time
converted into a dry and portable manure, although, I understand, this
manufacture is not now prosecuted. The dead animal after being skinned
is cut up and boiled in large cauldrons until the flesh is separated
from the bones. The latter are removed, and the flesh dried upon a flat
stove. The flesh as sold has the following composition:--
Water 12.17
Organic matter 78.44
Phosphate of lime, etc. 3.82
Alkaline salts 3.64
Sand 1.93
------
100.00
Nitrogen 9.22
Ammonia to which the nitrogen is }
equivalent } 11.20
The dried flesh and small bones of cattle, from the great slaughtering
establishments of South America, was at one time imported into this
country under the name of flesh manure. Its composition was--
Water 9.05
Fat 11.13
Animal matter 39.52
Phosphate of lime 28.74
Carbonate of lime 3.81
Alkaline salts 0.57
Sand 7.18
------
100.00
Nitrogen 5.56
Ammonia to which the nitrogen is }
equivalent } 6.67
But owing to the large proportion of phosphates contained in it, it may
be most fairly compared with bones. It is not now imported, the results
obtained from its use being said not to have proved satisfactory,
although this statement appears very paradoxical.
_Fish_ have been employed in considerable quantity as a manure. That
most extensively employed in this country is the sprat, which is
occasionally caught in enormous quantities on the Norfolk coast, and
used as an application for turnips. They are sold at 8d. per bushel,
and their composition is--
Water 64.6
Organic matter 33.3
Ash 2.1
-----
100.0
Nitrogen 1.90
Phosphoric acid 0.91
The refuse of herring and other fish-curing establishments, whales'
blubber, and similar fish refuse, are all useful as manure, and are
employed whenever they can be obtained. They are not usually employed
alone, but are more advantageously made into composts with their own
weight of soil, and allowed to ferment thoroughly before being applied.
Many attempts have been made to convert the offal of the great
fish-curing establishments, and the inedible fish, of which large
quantities are often caught, into a dry manure, which has received the
name of "fish guano." The processes employed have consisted in boiling
with sulphuric acid and other agents, and then evaporating, or sometimes
by simply drying up the refuse by steam heat. A manure made in this way
proved to have the following composition:--
Water 8.00
Fatty matters 7.20
Nitrogeneous organic matters 71.46
Phosphate of lime 8.70
Alkaline salts 3.80
Sand 0.84
------
100.00
Nitrogen 11.25
Equal to ammonia 13.68
Phosphoric acid in the alkaline salts, } 0.65
equal to 1.41 phosphate of lime }
The expense of manufacturing manures of this description has hitherto
acted as a barrier to their introduction. In this country several
manufactories have been established, but either owing to this cause, or
to the difficulty of obtaining sufficiently large and uniform supplies
of the raw material, some of them have not proved successful, but a
manufactory is now in operation in Norway, which exports the manure to
Germany. It is probable that most of the processes used in this country
failed because they were too costly, and it is much to be desired that
the subject should be actively taken up. It is said that the refuse from
the Newfoundland fisheries is capable of yielding about 10,000 tons of
fish guano annually; and the quantity obtainable on our own coasts is
also very considerable.
_Bones._--Bones have been used as a manure for a long period, but they
first attracted the particular attention of agriculturists from the
remarkable effects produced by their application on the exhausted
pasture lands of Cheshire. During the present century they came into
general use on arable land, and especially as a manure for turnips; and
they are now imported in large quantities from the continent of Europe.
The bones used in agriculture are chiefly those of cattle, but sheep and
horse bones are also employed. They do not differ much in quality when
genuine. The subjoined analysis is that of a good sample.
Water 6.20
Organic matter 39.13
Phosphate of lime 48.95
Lime 2.57
Magnesia 0.30
Sulphuric acid 2.55
Silica 0.30
------
100.00
Ammonia which the organic matter }
is capable of yielding } 4.80
In general, bones may be said to contain about half their weight of
phosphate of lime, and 10 or 12 per cent of water. But, in addition to
their natural state, they are met with in other forms in commerce, in
which their organic matter has been extracted either by boiling or
burning. The latter is especially common in the form of the spent animal
charcoal of the sugar refiners, which usually contains from 70 to 80 per
cent of phosphate of lime, but when deprived of their organic matter,
they may be more correctly considered under the head of mineral manures.
From the analysis given above, it is obvious that the manurial value of
bones is dependent partly on their phosphates and partly on the ammonia
they yield. It has been common to attribute their entire effects to the
former, but this is manifestly erroneous; and although there are no
doubt cases in which the former act most powerfully, the benefit derived
from the ammonia yielded by the organic matter is unequivocal. When the
phosphates only are of use, burnt bones or the spent animal charcoal of
the sugar refiners are to be preferred.
At their first introduction, bones were applied in large fragments, and
in quantities of from 20 to 30 cwt., or even more, per acre, but as
their use became more general they were gradually employed in smaller
pieces, until at last they were reduced to dust, and it was found that,
in a fine state of division, a few hundredweights produced as great an
effect as the larger quantity of the unground bones. Even the most
complete grinding which can be attained, however, leaves the bones in a
much less minute state of division than guano, and they necessarily act
more slowly than it does, the more especially as they contain no
ready-formed ammonia. They may be still further reduced by fermentation,
which acts by decomposing the organic matter, and causing the production
of ammonia; but not as is frequently, though erroneously supposed, by
converting the phosphates into a soluble condition, for this does not
occur to any extent, and their more rapid action is solely due to the
partial decomposition of the organic matter, by which it is brought into
a condition capable of undergoing a more rapid change in the soil. The
rapidity of action of bones is still more promoted by solution in
sulphuric acid, by which they are converted into the form of dissolved
bones or superphosphate. At the present moment, however, very little of
the superphosphates sold in the market are made exclusively from bones
in their natural state, by far the larger portion being manufactured
from mineral phosphates, or from bones after destruction of their
organic matter, sometimes with the addition of small quantities of
unburnt bones, but more frequently of sulphate of ammonia, to yield the
requisite quantity of ammonia. These substances may therefore be best
considered under the head of mineral manures.