[1] _Manucodiata_ was used by M. J. Brisson (_Ornithologie_, ii. 130)
as a generic term equivalent to the Linnaean _Paradisea_. In 1783
Boddaert, when assigning scientific names to the birds figured by
Daubenton, called the subject of one of them (_Pl. enlum._ 634)
_Manucodia chalybea_, the first word being apparently an accidental
curtailment of the name of Brisson's genus to which he referred it.
Nevertheless some writers have taken it as evidence of an intention
to found a new genus by that name, and hence the importation of
_Manucodia_ into scientific nomenclature, and the English form to
correspond.
MANUEL I., COMNENUS (c. 1120-1180), Byzantine emperor (1143-1180), the
fourth son of John II., was born about 1120. Having distinguished
himself in his father's Turkish war, he was nominated emperor in
preference to his elder surviving brother. Endowed with a fine physique
and great personal courage, he devoted himself whole-heartedly to a
military career. He endeavoured to restore by force of arms the
predominance of the Byzantine empire in the Mediterranean countries, and
so was involved in conflict with his neighbours on all sides. In 1144 he
brought back Raymond of Antioch to his allegiance, and in the following
year drove the Turks out of Isauria. In 1147 he granted a passage
through his dominions to two armies of crusaders under Conrad III. of
Germany and Louis VII. of France; but the numerous outbreaks of overt or
secret hostility between the Franks and the Greeks on their line of
march, for which both sides were to blame, nearly precipitated a
conflict between Manuel and his guests. In the same year the emperor
made war upon Roger of Sicily, whose fleet captured Corfu and plundered
the Greek towns, but in 1148 was defeated with the help of the
Venetians. In 1149 Manuel recovered Corfu and prepared to take the
offensive against the Normans. With an army mainly composed of mercenary
Italians he invaded Sicily and Apulia, and although the progress of both
these expeditions was arrested by defeats on land and sea, Manuel
maintained a foothold in southern Italy, which was secured to him by a
peace in 1155, and continued to interfere in Italian politics. In his
endeavour to weaken the control of Venice over the trade of his empire
he made treaties with Pisa and Genoa; to check the aspirations of
Frederic I. of Germany he supported the free Italian cities with his
gold and negotiated with pope Alexander III. In spite of his
friendliness towards the Roman church Manuel was refused the title of
"Augustus" by Alexander, and he nowhere succeeded in attaching the
Italians permanently to his interests. None the less in a war with the
Venetians (1172-74), he not only held his ground in Italy but drove his
enemies out of the Aegean Sea. On his northern frontier Manuel reduced
the rebellious Serbs to vassalage (1150-52) and made repeated attacks
upon the Hungarians with a view to annexing their territory along the
Save. In the wars of 1151-53 and 1163-68 he led his troops into Hungary
but failed to maintain himself there; in 1168, however, a decisive
victory near Semlin enabled him to conclude a peace by which Dalmatia
and other frontier strips were ceded to him. In 1169 he sent a joint
expedition with King Amalric of Jerusalem to Egypt, which retired after
an ineffectual attempt to capture Damietta. In 1158-59 he fought with
success against Raymond of Antioch and the Turks of Iconium, but in
later wars against the latter he made no headway. In 1176 he was
decisively beaten by them in the pass of Myriokephalon, where he allowed
himself to be surprised in line of march. This disaster, though partly
retrieved in the campaign of the following year, had a serious effect
upon his vitality; henceforth he declined in health and in 1180
succumbed to a slow fever.
In spite of his military prowess Manuel achieved but in a slight degree
his object of restoring the East Roman empire. His victories were
counterbalanced by numerous defeats, sustained by his subordinates, and
his lack of statesmanlike talent prevented his securing the loyalty of
his subjects. The expense of keeping up his mercenary establishment and
the sumptuous magnificence of his court put a severe strain upon the
financial resources of the state. The subsequent rapid collapse of the
Byzantine empire was largely due to his brilliant but unproductive
reign. Manuel married, firstly, a sister-in-law of Conrad III. of
Germany; and secondly, a daughter of Raymond of Antioch. His successor,
Alexis II., was a son of the latter.
See John Cinnamus, _History of John and Manuel_ (ed. 1836, Bonn); E.
Gibbon, _The Decline and Fall of the Roman Empire_ (ed. Bury, London,
1896), v. 229 sqq., vi. 214 sqq.; G. Finlay, _History of Greece_ (ed.
1877, Oxford), iii. 143-197; H. v. Kap-Herr, _Die abendländische
Politik Kaiser Manuels_ (Strassburg, 1881). (M. O. B. C.)
MANUEL II. PALAEOLOGUS (1350-1425), Byzantine emperor from 1391 to 1425,
was born in 1350. At the time of his father's death he was a hostage at
the court of Bayezid at Brusa, but succeeded in making his escape; he
was forthwith besieged in Constantinople by the sultan, whose victory
over the Christians at Nicopolis, however (Sept. 28, 1396), did not
secure for him the capital. Manuel subsequently set out in person to
seek help from the West, and for this purpose visited Italy, France,
Germany and England, but without material success; the victory of Timur
in 1402, and the death of Bayezid in the following year were the first
events to give him a genuine respite from Ottoman oppression. He stood
on friendly terms with Mahommed I., but was again besieged in his
capital by Murad II. in 1422. Shortly before his death he was forced to
sign an agreement whereby the Byzantine empire undertook to pay tribute
to the sultan.
Manuel was the author of numerous works of varied
character--theological, rhetorical, poetical and letters. Most of
these are printed in Migne, _Patrologia graeca_, clvi.; the letters
have been edited by E. Legrand (1893). There is a special monograph,
by B. de Xivrey (in _Mémoires de l'Institut de France_, xix. (1853),
highly commended by C. Krumbacher, whose _Geschichte der
byzantinischen Litteratur_ (1897) should also be consulted.
MANUEL I. (d. 1263), emperor of Trebizond, surnamed the Great Captain
([Greek: ho stratêgikôtatos]), was the second son of Alexius I., first
emperor of Trebizond, and ruled from 1228 to 1263. He was unable to
deliver his empire from vassalage, first to the Seljuks and afterwards
to the Mongols. He vainly negotiated for a dynastic alliance with the
Franks, by which he hoped to secure the help of Crusaders.
MANUEL II., the descendant of Manuel I., reigned only a few months in
1332-1333. Manuel III. reigned from 1390 to 1417, but the only interest
attaching to his name arises from his connexion with Timur, whose vassal
he became without resistance.
See G. Finlay, _History of Greece_ (ed. 1877, Oxford), iv. 338-340,
340-341, 386; Ph. Fallmerayer, _Geschichte des Kaisertums Trapezunt_
(Munich, 1827), i. chs. 8, 14, ii. chs. 4, 5; T. E. Evangelides,
[Greek: Historia tês Trapezountos] (Odessa, 1898), 71-73, 87-88,
126-132.
MANUEL, EUGENE (1823-1901), French poet and man of letters, was born in
Paris, the son of a Jewish doctor, on the 13th of July 1823. He was
educated at the École Normale, and taught rhetoric for some years in
provincial schools and then in Paris. In 1870 he entered the department
of public instruction, and in 1878 became inspector-general. His works
include: _Pages intimes_ (1866), which received a prize from the
Academy; _Poèmes populaires_ (1874); _Pendant la guerre_ (1871),
patriotic poems, which were forbidden in Alsace-Lorraine by the German
authorities; _En voyage_ (1881), poems; _La France_ (4 vols.,
1854-1858); a school-book written in collaboration with his
brother-in-law, Lévi Alavarès; _Les Ouvriers_ (1870), a drama dealing
with social questions, which was crowned by the Academy; _L'Absent_
(1873), a comedy; _Poésies du foyer et de l'école_ (1889), and editions
of the works of J. B. Rousseau (1852) and André Chénier (1884). He died
in Paris in 1901.
His _Poésies complètes_ (2 vols., 1899) contained some fresh poems; to
his _Mélanges en prose_ (Paris, 1905) is prefixed an introductory note
by A. Cahen.
MANUEL, JACQUES ANTOINE (1775-1827), French politician and orator, was
born on the 10th of December 1775. When seventeen years old he entered
the army, which he left in 1797 to become a lawyer. In 1814 he was
chosen a member of the chamber of representatives, and in 1815 he urged
the claim of Napoleon's son to the French throne and protested against
the restoration of the Bourbons. After this event be actively opposed
the government, his eloquence making him the foremost orator among the
members of the Left. In February 1823 his opposition to the proposed
expedition into Spain to help Ferdinand VII. against his rebellious
subjects produced a tumult in the Assembly. Manuel was expelled, but he
refused to accept this sentence, and force was employed to remove him.
He died on the 20th of August 1827.
MANUEL, LOUIS PIERRE (1751-1793), French writer and Revolutionist, was
born at Montargis (Loiret). He entered the Congregation of the Christian
Doctrine, and became tutor to the son of a Paris banker. In 1783 he
published a pamphlet, called _Essais historiques, critiques,
littéraires, et philosophiques_, for which he was imprisoned in the
Bastille. He embraced the revolutionary ideas, and after the taking of
the Bastille became a member of the provisional municipality of Paris.
He was one of the leaders of the _émeutes_ of the 20th of June and the
10th of August 1792, played an important part in the formation of the
revolutionary commune which assured the success of the latter _coup_,
and was made _procureur_ of the commune. He was present at the September
massacres and saved several prisoners, and on the 7th of September 1792
was elected one of the deputies from Paris to the convention, where he
was one of the promoters of the proclamation of the republic. He
suppressed the decoration of the Cross of St Louis, which he called a
stain on a man's coat, and demanded the sale of the palace of
Versailles. His missions to the king, however, changed his sentiments;
he became reconciled to Louis, courageously refused to vote for the
death of the sovereign, and had to tender his resignation as deputy. He
retired to Montargis, where he was arrested, and was guillotined in
Paris on the 17th of November 1793. Besides the work cited above and his
political pamphlets, he was the author of _Coup d'oeil philosophique sur
le règne de St Louis_ (1786); _L'Année française_ (1788); _La Bastille
dévoilée_ (1789); _La Police de Paris dévoilée_ (1791); and _Lettres sur
la Révolution_ (1792). In 1792 he was prosecuted for publishing an
edition of the _Lettres de Mirabeau à Sophie_, but was acquitted.
MANUEL DE MELLO, DOM FRANCISCO (? 1611-1666), Portuguese writer, a
connexion on his father's side of the royal house of Braganza, was a
native of Lisbon. He studied the Humanities at the Jesuit College of S.
Antão, where he showed a precocious talent, and tradition says that at
the age of fourteen he composed a poem in _ottava rima_ to celebrate the
recovery of Bahia from the Dutch, while at seventeen he wrote a
scientific work, _Concordancias mathematicas_. The death of his father,
Dom Luiz de Mello, drove him early to soldiering, and having joined a
contingent for the Flanders war, he found himself in the historic storm
of January 1627, when the pick of the Portuguese fleet suffered
shipwreck in the Bay of Biscay. He spent much of the next ten years of
his life in military routine work in the Peninsula, varied by visits to
the court of Madrid, where he contracted a friendship with the Spanish
poet Quevedo and earned the favour of the powerful minister Olivares. In
1637 the latter despatched him in company with the conde de Linhares on
a mission to pacify the revolted city of Evora, and on the same occasion
the duke of Braganza, afterwards King John IV. (for whom he acted as
confidential agent at Madrid), employed him to satisfy King Philip of
his loyalty to the Spanish crown. In the following year he suffered a
short imprisonment in Lisbon. In 1639 he was appointed colonel of one of
the regiments raised for service in Flanders, and in June that year he
took a leading part in defending Corunna against a French fleet
commanded by the archbishop of Bordeaux, while in the following August
he directed the embarcation of an expeditionary force of 10,000 men when
Admiral Oquendo sailed with seventy ships to meet the French and Dutch.
He came safely through the naval defeat in the channel suffered by the
Spaniards at the hands of Van Tromp, and on the outbreak of the
Catalonian rebellion became chief of the staff to the commander-in-chief
of the royal forces, and was selected to write an account of the
campaign, the _Historia de la guerra de Cataluña,_ which became a
Spanish classic. On the proclamation of Portuguese independence in 1640
he was imprisoned by order of Olivares, and when released hastened to
offer his sword to John IV. He travelled to England, where he spent some
time at the court of Charles I., and thence passing over to Holland
assisted the Portuguese ambassador to equip a fleet in aid of Portugal,
and himself brought it safely to Lisbon in October 1641. For the next
three years he was employed in various important military commissions
and further busied himself in defending by his pen the king's title to
his newly acquired throne. An intrigue with the beautiful countess of
Villa Nova, and her husband's jealousy, led to his arrest on the 19th of
November 1644 on a false charge of assassination, and he lay in prison
about nine years. Though his innocence was clear, the court of his
Order, that of Christ, influenced by his enemies, deprived him of his
_commenda_ and sentenced him to perpetual banishment in India with a
heavy money fine, and the king would not intervene to save him. Owing
perhaps to the intercession of the queen regent of France and other
powerful friends, his sentence was finally commuted into one of exile to
Brazil. During his long imprisonment he finished and printed his history
of the Catalonian War, and also wrote and published a volume of Spanish
verses and some religious treatises, and composed in Portuguese a volume
of homely philosophy, the _Carta de Guia de Casados_ and a _Memorial_ in
his own defence to the king, which Herculano considered "perhaps the
most eloquent piece of reasoning in the language." During his exile in
Brazil, whither he sailed on the 17th of April 1655, he lived at Bahia,
where he wrote one of his _Epanaphoras de varia historia_ and two parts
of his masterpiece, the _Apologos dialogaes_. He returned home in 1659,
and from then until 1663 we find him on and off in Lisbon, frequenting
the celebrated _Academia dos Generosos_, of which he was five times
elected president. In the last year he proceeded to Parma and Rome, by
way of England, and France, and Alphonso VI. charged him to negotiate
with the Curia about the provision of bishops for Portuguese sees and to
report on suitable marriages for the king and his brother. During his
stay in Rome he published his _Obras morales_, dedicated to Queen
Catherine, wife of Charles II. of England, and his _Cartas familiares_.
On his way back to Portugal he printed his _Obras metricas_ at Lyons in
May 1665, and he died in Lisbon the following year.
Manuel de Mello's early Spanish verses are tainted with Gongorism, but
his Portuguese sonnets and _cartas_ on moral subjects are notable for
their power, sincerity and perfection of form. He strove successfully to
emancipate himself from foreign faults of style, and by virtue of his
native genius, and his knowledge of the traditional poetry of the
people, and the best Quinhentista models, he became Portugal's leading
lyric poet and prose writer of the 17th century. As with Camoens,
imprisonments and exile contributed to make Manuel de Mello a great
writer. His _Letters_, addressed to the leading nobles, ecclesiastics,
diplomats and literati of the time, are written in a conversational
style, lighted up by flashes of wit and enriched with apposite
illustrations and quotations. His commerce with the best authors appears
in the _Hospital das lettras_, a brilliant chapter of criticism forming
part of the _Apologos dialogaes_. His comedy in _redondilhas_, the _Auto
do Fidalgo Aprendiz_, is one of the last and quite the worthiest
production of the school of Gil Vicente, and may be considered an
anticipation of Molière's _Le Bourgeois gentilhomme_.
There is no uniform edition of his works, but a list of them will be
found in his _Obras morales_, and the various editions are set out in
Innocencio da Silva's _Diccionario bibliographico portugues_. See _Dom
Francisco Manuel de Mello, his Life and Writings_, by Edgar Prestage
(Manchester, 1905), "D. Francisco Manuel de Mello, documentos
biographicos" and "D. Francisco Manuel de Mello, obras autographas e
ineditas," by the same writer, in the _Archivo historico portuguez_
for 1909. Manuel de Mello's prose style is considered at length by G.
Cirot in _Mariana historien_ (Bordeaux, 1905). pp. 378 seq.
(E. Pr.)
MANUL (_Felis manul_), a long-haired small wild cat from the deserts of
Central Asia, ranging from Tibet to Siberia. The coat is long and soft,
pale silvery grey or light buff in hue, marked with black on the chest
and upper parts of the limbs, with transverse stripes on the loins and
rings on the tail of the same hue. The Manul preys upon small mammals
and birds. A separate generic name, _Trichaelurus_, has been proposed
for this species by Dr K. Satunin.
MANURES AND MANURING. The term "manure" originally meant that which was
"worked by hand" (Fr. _manoeuvre_), but gradually came to apply to any
process by which the soil could be improved. Prominent among such
processes was that of directly applying "manure" to the land, manure in
this sense being what we now call "farmyard manure" or "dung," the
excreta of farm animals mixed with straw or other litter. Gradually,
however, the use of the term spread to other materials, some of home
origin, some imported, some manufactured by artificial processes, but
all useful as a means of improving the fertility of the soil. Hence we
have two main classes of manures: (a) what may be termed "natural
manures," and (b) "artificial manures." Manures, again, may be divided
according to the materials from which they are made--e.g. "bone manure,"
"fish manure," "wool manure," &c.; or according to the constituents
which they mainly supply--e.g. "phosphatic manures," "potash manures,"
"nitrogenous manures," or there may be numerous combinations of these to
form mixed or "compound" manures. Whatever it be, the word "manure" is
now generally applied to anything which is used for fertilizing the
soil. In America the term "fertilizers" is more generally adopted, and
in Great Britain the introduction of the "Fertilizers and Feeding Stuffs
Act" has effected a certain amount of change in the same direction. The
modern tendency to turn attention less to the consideration of manurial
applications given to land and more to the physical and mechanical
changes introduced thereby in the soil itself, would seem to be carrying
the word "manure" back more to its original meaning.
The subject of manures and their application involves a prior
consideration of plant life and its requirements. The plant, growing in
the soil, and surrounded by the atmosphere, derives from these two
sources its nourishment and means of growth through the various stages
of its development.
Chemical analysis has shown that plants are composed of water, organic
or combustible matters, and inorganic or mineral matters. Water
constitutes by far the greater part of a living plant; a grass crop
will contain about 75% of water, a turnip crop 89 or 90%. The organic
or combustible matters are those which are lost, along with the water,
when the plant is burnt; the inorganic or mineral matters are those
which are left behind as an "ash" after the burning. The combustible
matter is composed of six elements: carbon, hydrogen, oxygen,
nitrogen, sulphur and a little phosphorus. About one-half of the
combustible matter of plants is carbon. Along with hydrogen and oxygen
the carbon forms the cellulose, starch, sugar, &c., which plants
contain, and with these same elements and sulphur the carbon forms the
albuminoids of plants. The inorganic or mineral matters comprise a
comparatively small part of the plant, but they contain, as essential
constituents of plant life, the following elements: potassium,
calcium, magnesium, iron, phosphorus and sulphur. In addition, other,
but not essential, elements are found in the ash e.g. sodium, silicon
and chlorine, together with small quantities of manganese and other
rarer elements.
The above constituents that have been classed as "essential," are
necessary for the growth of the plant, and absence of any one will
involve failure. This has been shown by growing plants in water
dissolved in which are salts of the elements present in plants. By
omitting in turn one or other of the elements aforesaid it is found
that the plants will not grow after they have used up the materials
contained in the seed itself. These elements are accordingly termed
"essential," and it therefore becomes necessary to inquire how they
are to be supplied.
The atmosphere is the great storehouse of organic plant food. The
leaves take up, through their stomata, the carbonic acid and other
gases of the atmosphere. The carbonic acid, under the influence of
light, is decomposed in the chlorophyll cells, oxygen is given off and
carbon is assimilated, being subsequently built up into the various
organic bodies forming the plant's structure. It would seem, too, that
plants can take up a small quantity of ammonia by their leaves, and
also water to some extent, but the free or uncombined nitrogen of the
air cannot be directly assimilated by the leaves of plants.
From the soil, on the other hand, the plant obtains, by means of its
roots, its mineral requirements, also sulphur and phosphorus, and
nearly all its nitrogen and water. Carbon, too, in the case of fungi,
is obtained from the decayed vegetable matter in the soil. The roots
are able not only to take up soluble salts that are presented to them,
but they can attack and render soluble the solid constituents of the
soil, thus transforming them into available plant food. In this way
important substances, such as phosphoric acid and potash, are supplied
to the plant, as also lime. Roots can further supply themselves with
nitrogen in the form of nitrates, the ammonia and other nitrogenous
bodies undergoing ready conversion into nitrates in the soil. These
various mineral constituents, being now transferred to the plant, go
to form new tissue, and ultimately seed, or else accumulate in the sap
and are deposited on the older tissue.
Whether the nitrogen of the air can be utilized by plants or not has
been long and strenuously discussed, Boussingault first, and then
Lawes, Gilbert and Pugh, maintaining that there was no evidence of
this utilization. But it was always recognized that certain plants,
clover for example, enriched the land with nitrogen to an extent
greater than could be accounted for by the mere supply to them of
nitrates in the soil. Ultimately Hellriegel supplied the explanation
by showing that, at all events, certain of the Leguminosae, by the
medium of swellings or "nodules" on their roots, were able to fix the
atmospheric nitrogen in the soil, and to convert it into nitrates for
the use of the plant. This was found to be the result of the action of
certain organisms within the nodules themselves, which in turn fed
upon the carbohydrates of the plant and were thus living in a state of
"symbiosis" with it. So far, however, this has not been shown to be
the case with any other plants than the Leguminosae, and, though it is
asserted by some that many other plants can take up the nitrogen of
the air directly through their leaves, there is no clear evidence as
yet of this.
We must now consider how the different requirements of the plant in
regard to the elements necessary to maintain its life and to build up
its structure affect the question of manuring.
Under conditions of natural growth and decay, when no crops are gathered
in, or consumed on the land by live stock, the herbage, on dying down
and decaying, returns to the atmosphere and the soil the elements taken
from them during life; but, under cultivation, a succession of crops
deprives the land of the constituents which are essential to healthy and
luxuriant growth. Without an adequate return to the land of the matters
removed in the produce, its fertility cannot be maintained for many
years. In newly opened countries, where old forests have been cleared
and the land brought under cultivation, the virgin soil often possesses
at first a high degree of fertility, but gradually its productive power
decreases from year to year. Where land is plentiful and easy to be
obtained it is more convenient to clear fresh forest land than to
improve more or less exhausted land by the application of manure, labour
and skill. But in all densely peopled countries, and where the former
mode of cultivation cannot be followed, it is necessary to resort to
artificial means to restore the natural fertility of the land and to
maintain and increase its productiveness. That continuous cropping
without return of manure ends in deterioration of the soil is well seen
in the case of the wheat-growing areas in America. Crops of wheat were
taken one after another, the straw was burned and nothing was returned
to the land; the produce began to fall off and the cultivators moved on
to fresh lands, there to meet, in time, with the same experience; and
now that the available land has been more or less intensely occupied, or
that new land is too far removed for ready transport of the produce, it
has been found necessary to introduce the system of manuring, and
America now manufactures and uses for herself large quantities of
artificial and other manures.
That the same exhaustion of soil would go on in Great Britain, if
unchecked by manuring, is known to every practical farmer, and, if
evidence were needed, it is supplied by the renowned Rothamsted
experiments of Lawes and Gilbert, on a heavy land, and also by the more
recent Woburn experiments of the Royal Agricultural Society of England,
conducted on a light sandy soil. The following table will illustrate
this point, and show also how under a system of manuring the fertility
is maintained:--
TABLE 1.--Showing Exhaustion of Land by continuous Cropping without
Manure, and the maintenance of fertility through manuring. (Rothamsted
50 years; Woburn 30 years.)
+-----------------------------------------------------------------------------------------------------------+
| 1. Rothamsted (heavy land). |
+------+-----+--------------+-------------------------------------------------------------------------------+
| | | | Average yield of corn per acre. |
| | | +----------+----------+----------+----------+----------+----------+-------------+
|Crop. |Plot.| Treatment. | 8 years, | 10 years,| 10 years,| 10 years,| 10 years,| 10 years,| Average |
| | | |1844-1851.|1852-1861.|1862-1871.|1872-1881.|1882-1891.|1892-1901.| of 50 years,|
| | | | | | | | | | 1852-1901. |
+------+-----+--------------+----------+----------+----------+----------+----------+----------+-------------+
| | | | Bush. | Bush. | Bush. | Bush. | Bush. | Bush. | Bush. |
|Wheat | 3 |Unmanured | | | | | | | |
| | | continuously | 17.2 | 15.9 | 14.5 | 10.4 | 12.6 | 12.3 | 43.1 |
| | 2 |Farm-yard | | | | | | | |
| | | manure yearly| 28.0 | 34.2 | 37.5 | 28.7 | 38.2 | 39.2 | 35.6 |
|Barley| 7-2 |Unmanured | | | | | | | |
| | | continuously | -- | 22.4 | 17.5 | 13.7 | 12.7 | 10.0 | 15.3 |
| | 1-0 |Farm-yard | | | | | | | |
| | | manure yearly| -- | 45.0 | 51.5 | 50.2 | 47.6 | 44.3 | 47.7 |
+------+-----+--------------+----------+----------+----------+----------+----------+----------+-------------+
| 2. Woburn (light land). |
+------+-----+--------------+-------------------------------------------------------------------------------+
| | | | Average yield of corn per acre. |
| | | +-------------------+-------------------+-------------------+-------------------+
|Crop. |Plot.| Treatment. | 10 years, | 10 years, | 10 years, | Average |
| | | | 1877-1886. | 1887-1896. | 1897-1906. | of 30 years, |
| | | | | | | 1877-1906. |
+------+-----+--------------+-------------------+-------------------+-------------------+-------------------+
| | | | Bush. | Bush. | Bush. | Bush. |
|Wheat | 7 |Unmanured | | | | |
| | | continuously | 17.4 | 14.5 | 10.8 | 14.2 |
| | 11b |Farm-yard | | | | |
| | | manure yearly| 26.7 | 27.8 | 24.0 | 26.2 |
|Barley| 7 |Unmanured | | | | |
| | | continuously | 23.0 | 18.1 | 13.3 | 18.1 |
| | 11b |Farm-yard | | | | |
| | | manure yearly| 40.0 | 39.9 | 36.6 | 38.8 |
+------+-----+--------------+-------------------+-------------------+-------------------+-------------------+
Whereas on the heavier and richer land of Rothamsted the produce of
unmanured wheat has fallen in 58 years from 17.2 bushels to 12.3
bushels, on the lighter and poorer soil of Woburn it has fallen in 30
years from 17.4 bushels to 10.8 bushels; barley has in 50 years at
Rothamsted gone from 22.4 bushels to 10 bushels, whilst at Woburn (which
is better suited for barley) it has fallen in 30 years from 23 bushels
to 13.3 bushels. At both Rothamsted and Woburn the application of
farm-yard manure has kept the produce of wheat and barley practically up
to what it was at the beginning, or even increased it. Similar
conclusions can be drawn from the use of artificial manures at each of
the experimental stations named, exemplifying the fact that with
suitable manuring crops of wheat or barley can be grown years after year
without the land undergoing deterioration, whereas if left unmanured it
gradually declines in fertility. Practical proof has further been given
of this in the well-known "continuous corn-growing" system pursued, in
his regular farming, by Mr John Prout of Sawbridgeworth, Herts, and
subsequently by his son, Mr W. A. Prout, since the year 1862. By
supplying, in the form of artificial manures, the necessary constituents
for his crops, Mr Prout was enabled to grow year after year, with only
an occasional interval for a clover crop and to allow of cleaning the
land, excellent crops of wheat, barley and oats, and without, it may be
added, the use of farm-yard manure at all.
In considering the economical use of manures on the land regard must be
had to the following points: (1) the requirements of the crops intended
to be cultivated; (2) the physical condition of the soil; (3) the
chemical composition of the soil; and (4) the composition of the manure.
Briefly stated, the guiding principle of manuring economically and
profitably is to meet the requirements of the crops intended to be
cultivated, by incorporating with the soil, in the most efficacious
states of combination, the materials in which it is deficient, or which
the various crops usually grown on the farm do not find in the land in a
sufficiently available condition to ensure an abundant harvest. Soils
vary greatly in composition, and hence it will be readily understood
that in one locality or on one particular field a certain manure may be
used with great benefit, while in another field the same manure has
little or no effect upon the produce.
For plant life to thrive certain elements are necessary, viz. carbon,
hydrogen, oxygen, nitrogen, sulphur, phosphorus, among the organic or
combustible matters, and among the inorganic or mineral matters,
potassium, calcium, magnesium, iron, phosphorus and sulphur. We must now
examine the extent to which these necessary elements occur in either of
the two great storehouses, the atmosphere and the soil, and how their
removal in the form of crops may be made up for by the use of manures,
so that the soil may be maintained in a state of fertility. Further, we
must consider what functions these elements perform in regard to plant
life, and, lastly, the forms in which they can best be applied for the
use of crops.
Of carbon, hydrogen and oxygen there is no lack, the atmosphere
providing carbonic acid in abundance, and rain giving the elements
hydrogen and oxygen, so that these are supplied from natural sources.
Iron, magnesium and sulphur also are seldom or never deficient in soils,
and do not require to be supplemented by manuring. Accordingly, the
elements for which there is the greatest demand by plants, and which the
soil does not provide in sufficiency, are nitrogen, phosphorus,
potassium, and, possibly, calcium. Manuring, apart from the physical and
mechanical advantages which it confers upon soils, practically resolves
itself, therefore, into the supply of nitrogen, phosphorus and
potassium, and it is with the supply of these that we shall accordingly
deal in particular.
1. _Nitrogen._--Though we are still far from knowing what are the
exact functions which nitrogen fulfils in plant life, there is no
doubt as to the important part which it plays in the vegetable growth
of the plant and in the formation of stem and leaf. Without a
sufficiency of nitrogen the plant would be stunted in growth. Its
growth, indeed, may be said to be measured by the supply of nitrogen,
for while mineral constituents like phosphoric acid and potash are
only taken up to the extent that the plant can use them i.e. according
to its rate of growth, this actual growth itself would seem to be
determined by the extent of the nitrogen supply. This it is which
causes the ready response given to a crop by the application of some
quickly-acting nitrogenous material like nitrate of soda, and which is
marked by the dark-green colour produced and the pushing-on of the
growth. Similarly, this use of nitrogen, by prolonging growth, defers
maturity, while over-use of nitrogen tends to produce increase of leaf
and lateness of ripening. Along with this growth of the vegetative
portions, and seen, in the case of corn crops, mainly in the straw,
there is a corresponding decrease, from the use of nitrogen in excess,
in the quality of the grain. In corn a smaller grain and lesser weight
per bushel are the result of over-nitrogen manuring. The composition
of the grain is likewise affected, becoming more nitrogenous. With
crops, however, where rapid green growth is required, nitrogen effects
the purpose well, though here, too, over-manuring with nitrogen will
tend to produce rankness and coarseness of growth. Experiments at
Rothamsted and elsewhere, as well as everyday practice of the farm,
bear testimony to the paramount importance of nitrogen-supply, and to
the crops it is capable of raising. This applies not only to corn
crops of all kinds, but to root crops, grass, potatoes, &c. Leguminous
crops alone seem to have no need of it. In view of this practical
experience, Liebig's "mineral theory"--according to which he laid down
that plants only needed to have mineral constituents, such as
phosphoric acid, potash and lime, supplied to them--reads strangely
nowadays. The use of mineral manures without nitrogen other than that
already present in the soil or supplied in rain has been shown, alike
at Rothamsted and Woburn, to produce crops of wheat and barley little
better than those from unmanured land. The lack of nitrogen in
ordinary cultivated soils is much more marked than is that of mineral
constituents, and consequently even with the application of nitrogen
alone (as by the use of nitrate of soda or sulphate of ammonia), good
crops have been grown for a large number of years. This has been shown
both at Rothamsted and at Woburn. On the other hand, experiments at
these stations have demonstrated that better and more lasting results
are obtained by the judicious use of nitrogenous materials in
conjunction with phosphates and potash.
The form in which nitrogen is taken up by plants is mainly, if not
wholly, that of nitrates, which are readily-soluble salts. Ammonia and
other nitrogenous bodies undergo in the soil, through the agency of
nitrifying organisms present in it (_Bacterium nitrificans_, &c.),
rapid conversion into nitrates, and as such are easily assimilable by
the plant. Similarly, they are the constituents which are most readily
removed in drainage, and hence the adequate supply of nitrogen for the
plant's use is a constant problem in agriculture. Experiments on the
rate of removal of nitrates from the soil by drainage showed that
every inch of rain passing through the drains caused a loss of 2½ lb.
of nitrogen per acre (Voelcker and Frankland). At the same time,
soils, as Way showed, have the power of absorbing, in different
degrees, ammonia from its solution in water, and when salts of ammonia
are passed through soils the ammonia alone is absorbed, the acids
passing, generally in combination with lime, into the drainage.
Other experiments at Rothamsted on drainage showed that, though large
quantities of ammonia salts were applied to the land, the drainage
water contained merely traces of ammonia, but, on the other hand,
nitrates in quantity, thus proving that it is as nitrates, and not as
ammonia, that plants mainly, if not entirely, take up their
nitrogenous food.
From these investigations it follows that much more nitrogen must be
added to the land than would be needed to produce a given increase in
the crop. Nitrogen, then, being so all-important, the question is,
where is it to come from? We have seen that the leaves take up only
minute quantities of ammonia, comparatively small amounts are supplied
in the rain, dew, snow, &c.,[1] and in the case of Leguminosae alone
have we any evidence of plants being able to provide themselves with
nitrogen from atmospheric sources. Some few organisms present in
fertile soils, e.g. _Azotobacter chroococcum_, have also the power,
under certain conditions, of fixing the free nitrogen of the
atmosphere without the intervention of a "host," but all these sources
would be very inadequate to meet the demands of an intensive
cultivation. An ordinary fertile arable soil will not show, on
analysis, much more than .15% of nitrogen, and it is evident that the
great source of supply of the needed nitrogen must be the direct
manuring of the soil with materials containing nitrogen. These
materials will be considered in detail later.
2. _Phosphorus._--This is the most important mineral element which has
to be supplied to the soil by the agency of manuring. It occurs in
ordinary fertile soils to the extent of only about .15%, reckoned as
phosphoric acid, and though its absence in sufficiency is not so
marked or so soon shown under prolonged cultivation as is that of
nitrogen, yet the fact that it is needed by all classes of crops, and
that its application in manurial form is attended with great benefits,
makes its supply one of great importance. From the time that Liebig,
in 1840, suggested the treatment of bones with sulphuric acid in order
to make them more readily available for the use of crops, and that the
late Sir John Lawes (in 1843) began the dissolving of mineral
phosphates for the purpose of manufacturing superphosphate, the
"artificial manure" trade took its rise, and ever since then the whole
globe has been exploited for the purpose of obtaining the raw
phosphatic materials which form the base of the artificial manures of
the past and of the present day. The functions which phosphoric acid
fulfils in plant life would appear to be connected rather with the
maturing of the plant than with the actual growth of the structure.
Phosphates are found concentrated in those parts of the plant where
cell growth and reproduction are most active. More especially is this
the case with the seed in which phosphates are present in greatest
quantity. While nitrogen delays maturity, phosphoric acid has just the
opposite effect, and cereal crops not sufficiently supplied with it
ripen much more tardily than do others. Moreover, the grain is formed
more early when phosphatic manures have been given than when they are
withheld. Phosphates increase the proportion of corn to straw, and, as
regards the grain itself, they render it less nitrogenous, richer in
phosphates, and altogether improve its quality.
While these are the principal functions of phosphates, they also
exercise an influence on the young plant in its early stages. This is
well seen in the almost universal practice of applying superphosphate
to the young turnip or swede crop in order to push it beyond the
attack of "fly." Undoubtedly phosphates in readily available form
stimulate the young seedling, enabling it to develop root growth, and,
later on, causing the plant to "tiller out" well. Phosphoric acid
occurs in the soil bound up with the oxides of iron and alumina, or,
it may be, with lime, and the extent to which it may become useful to
plants will depend largely upon the readiness with which it becomes
available. For the purpose of ascertaining this different analytical
methods have been suggested, the best known one being that of B. Dyer,
in which a 1% solution of citric acid is used as a solvent. As a
result of experimenting with Rothamsted soils of known capability it
has been put forward that if a soil shows, by this treatment, less
than .01% of phosphoric acid it is in need of phosphatic manuring.
Experiments carried on for many years at Rothamsted and Woburn have
clearly established the beneficial effects of phosphatic manuring on
corn crops, for though no material increase marks the application of
mineral manures in the absence of nitrogen, yet the results when
phosphates and nitrogen are used together are very much greater than
when nitrogen alone has been applied; and this is true as regards not
only the better ripening and quality of the grain, but also as regards
the actual crop increase.
With root crops phosphates are almost indispensable; and, owing to the
limited power which these crops have of utilizing the phosphoric acid
in the soil, the supply of a readily available phosphatic manure like
superphosphate is of the highest importance.
The assimilation of phosphoric acid goes on in a cereal crop after the
time of flowering and to a later date than does that of nitrogen and
potash, and it is ultimately stored in the seed. Soils possess a
retentive power for phosphoric acid which enables the latter to be
conserved and not removed to any extent by drainage. This function is
exercised mainly by the presence of oxide of iron. Alumina acts in a
similar way. In the case of soils that contain clay only traces of
phosphoric acid are found in the drainage water.
3. _Potassium._--The element third in importance, which requires to be
supplied by manuring, is potassium, or, as it is generally expressed,
potash. This in its functions resembles phosphoric acid somewhat,
being concerned rather with the mature development of the plant than
with its actual increase of growth. Like phosphoric acid, potash is
found concentrated throughout the plant in the early stages of its
growth, but, unlike it, is in the case of a cereal crop all taken up
by the time of full bloom, whereas with phosphoric acid the
assimilation continues later. Potash would appear to have an intimate
connexion with the quality of crops, and to be favourable to the
production of seed and fruit rather than to stem and leaf development.
Certain crops, such as vegetables, fruit, hops, as well as root crops
generally, make special demands upon potash supply, and, as checking
the tendency to over-development of leaf, &c., induced by nitrogenous
manures when used alone, potash has great practical importance. Potash
appears to be bound up in a special way with the process of
assimilation, for it has been clearly shown that whenever potash is
deficient the formation of the carbohydrates, such as sugar, starch
and cellulose, does not go on properly. Hellriegel and Wilfarth showed
by experiment the dependence of starch formation on an adequate supply
of potash. Cereal grains remained small and undeveloped when potash
was withheld, because the formation of starch did not go on. The same
effect has been strikingly shown in the Rothamsted experiments with
mangels, a plot receiving potash salts as manure giving a crop of
roots nearly 2½ times as heavy as that grown on a plot which has
received no potash. In this case the increase is due almost entirely
to the sugar and other carbohydrates elaborated in the leaves, and not
to any increase of mineral constituents.
The effect of potash on maturity is somewhat uncertain, inasmuch as in
the case of grain crops it would appear to delay maturity and to
hasten it in that of root crops.
The influence of potash on particular crops is very marked. On clovers
and other leguminous crops it is highly beneficial, while on grass
land it is of particular importance as inducing the spread of clovers
and other leguminous herbage. This is well seen in the Rothamsted
grass experiments, where with a mineral manure containing potash
one-half of the herbage is leguminous in nature, whereas the same
manure without potash gives only 15% of leguminous plants. Similarly,
where nitrogen is used by itself and no potash given there are no
leguminous plants at all to be found. Potash occurs in an ordinary
fertile soil to the extent of about .20%; a sandy soil will have less,
a clay soil may have considerably more. Potash, however, is mostly
bound up in the soil in the form of insoluble silicates, and these are
often in a far from available form, but require cultivation, the use
of lime and other means for getting them acted on by the air and
moisture, and so liberating the potash. According to B. Dyer's method
of ascertaining the availability of potash in soils, the amount of
potash soluble in a 1% citric acid solution should be about .005%,
otherwise the addition of potash manures will be a requisite. In the
case of soils containing much lime a larger quantity would, no doubt,
be needed.
Potash, like phosphoric acid, is readily retained by soils, and so is
not subject to any considerable losses by drainage. This retention is
exercised by the ferric-oxide and alumina in soils, but still more so
by the double silicates, and to some extent also by the humus of the
soil. Potash will be liberated from its salts by the action of lime in
the soil, the lime taking the place of the potash. Lime is, therefore,
of much importance in setting free fresh stores of potash. Soda salts
also, when in considerable excess, are able to liberate potash from
its compounds, and to this is probably due, in many cases, the
beneficial action attending the use of common salt.
4. _Calcium._--Though calcium, or lime, is found in sufficiency in
most cultivated soils, there are, nevertheless, soils in which lime is
clearly deficient and where that deficiency has shown itself in
practice. Moreover, so comparatively easy is the removal of lime from
the soil by drainage, and so important is the part which lime plays in
liberating potash from its compounds, and in helping to retain bases
in the soil so that they are not lost in drainage, that the
significance of lime cannot be ignored. Further, the availability of
both potash and phosphoric acid in the soil has been found to be much
increased by the presence of lime. Lime, as carbonate of calcium, is
also necessary for the process of nitrification to go on in the soil.
Some sandy soils, and even some clays, contain so little lime as to
call for the direct supply of lime as an addition to the soil. When
this is the case nothing can adequately take the place of lime, and in
this sense lime may be called a "manure." In the majority of cases,
however, the practice of liming or chalking, which was a common one in
former times, was resorted to mainly because of the ameliorating
effects it produced on the land, both in a mechanical and in a
physical direction. Thus, on clay soil it flocculates the particles,
rendering the soil less tenacious of moisture, improving the drainage
and making the soil warmer. Nor must the directly chemical results be
overlooked, for in addition to those already mentioned, of liberating
plant food (chiefly potash and phosphoric acid), retaining bases, and
aiding nitrification, lime acts in a special way as regards the
sourness or "acidity" which is sometimes produced in land when lime is
deficient. In soils that are acid through the accumulation of humic
acid nitrification does not go on, and bacterial life is repressed.
The addition of lime has the effect of "sweetening" the land, and of
restoring its bacterial activity. This acidity is also seen in the
occurrence of the disease known as "finger and toe" in turnips, the
fungus producing this being one that thrives in an acid soil. It is
only found in soils poor in lime, and the only remedy for it is
liming. The growth of weeds like spurry, marigold, sorrel, &c., is
also a sign of land being wanting in lime. The most striking instance
of this "soil acidity" is that afforded by the Woburn experiments,
where, on a soil originally poor in lime, the soil has, through the
continuous use of ammonia salts, been impoverished of its lime to such
an extent that it has become quite sterile and is distinctly acid in
character. The application of lime, however, to such a soil has had
the effect of quite restoring its fertility.
The amount of lime which soils contain is a very variable one, chalk
soils being very rich in lime, whereas sandy and peaty soils are
generally very poor in it. If the amount of lime in a soil falls below
1% of carbonate of lime on the dried soil, the soil will sooner or
later require liming.
5. _Magnesium._--This is not known to be deficient in soils, although
an essential element in them, and it is seldom directly applied as a
manurial ingredient. Some natural potash salts, such as kainit,
contain magnesia salts in considerable quantity; but their influence
is not known to be of beneficial nature, though, like common salt,
magnesia salts will, doubtless, render some of the potash in the soil
available. At the same time magnesia salts are not without their
influence on crops, and experiments have been undertaken at the Woburn
experimental farm and elsewhere to determine the nature of this
influence. Carbonate of magnesia has been tried in connexion with
potato-growing, and, it is said, with good results.
6. _Iron._--Iron is another essential ingredient of soil that is found
in abundance and does not call for special application in manurial
form. Iron is essential for the formation of chlorophyll in the
leaves, and its presence is believed also to be beneficial for the
development of colour in flowers, and for producing flavour in fruits
and in vines especially. Ferrous sulphate has, partly with this view,
and partly for its fungus-resisting properties, been suggested as a
desirable constituent of manures. The function performed by ferric
oxide in the soil of retaining phosphoric acid, potash and ammonia has
been already alluded to.
7. _Sulphur._--This, the last of the "essential" elements, is seldom
specially employed in manurial form. There would appear to be no lack
of it for the plant's supply, and it is little required except for the
building-up, with carbon, hydrogen, oxygen and nitrogen, of the
albuminoids. There are few artificial manures which do not contain
considerable amounts of sulphur, notably superphosphate. Sulphate of
lime (gypsum) is sometimes applied to the land direct as a way of
giving lime; this is employed in the case of clover and hops
principally.
Having thus dealt with the essential ingredients which plants must have,
and which may require to be supplied to them in the form of additional
manures, we may briefly pass over the other constituents found in
plants, which may, or may not, be given as manures.
8. _Sodium._--This is a widely distributed element. The influence of
common salt (chloride of sodium) in liberating, when used in large
excess, potash from the silicates in which it is combined in the soil
has been already referred to, and in this way common salt and also
nitrate of soda (the two forms in which soda salts are used as
manures) may have some benefit. The principal purpose for which common
salt, however, is used, is that of retaining moisture in the land. It
is specially useful in a dry season, or for succulent crops such as
cabbage, kale, &c., or again for plants of maritime origin (such as
mangels), which thrive near the sea shore.
9. _Silicon._--All soils contain silica in abundance. Though silica
forms so large a part of the ash of plants and is especially abundant
in the straw of cereals, there is no evidence that it is required in
plant life. Popularly, it is believed to "stiffen" the stems of
cereals and grasses, but plants grown without it will do perfectly
well. It would, however, appear that soluble silica does play some
part in enabling phosphoric acid to be better assimilated by the
plant. Silicates, however, have not justified their use as direct
fertilizers.
10. _Chlorine._--A certain amount of chlorine is brought down in the
rain, and chlorides are also used in the form of common salt, with the
effect, as aforesaid, of liberating potash from silicates, when given
in excess, but there is no evidence as to any particular part which
the chlorine itself plays.
11. _Manganese_, &c.--Manganese occurs in minute quantities in most
plants, and it, along with lithium (found largely in the
tobacco-plant), caesium, titanium, uranium and other rare elements,
may be found in soils. Experiments at the Woburn pot-culture station
and elsewhere, point to stimulating effects on vegetation produced by
the action of minute doses of salts of these elements, but, so far,
their use as manurial ingredients need not be considered in practice.
12. _Humus._--Though not an element, or itself essential, this body,
which may be described as decayed vegetable matter, is not without
importance in plant life. Of it, farm-yard manure is to a large extent
composed, and many "organic manures," as they are termed, contain it
in quantity. Dead leaves, decayed vegetation, the stubble of cereal
crops and many waste materials add humus to the land, and this humus,
by exposure to the air, is always undergoing further changes in the
soil, opening it out, distributing carbonic acid through it, and
supplying it, in its further decomposition, with nitrogen. The
principal effects of humus on the soil are of a physical character,
and it exercises particular benefit through its power of retaining
moisture. Humus, however, has a distinct chemical action, in that it
forms combinations with iron, calcium and ammonia. It thus becomes one
of the principal sources of supply of the nitrogenous food of plants,
and a soil rich in humus is one rich in nitrogen. The nitrogen in
humus is not directly available as a food for plants, but many kinds
of fungi and bacteria are capable of converting it into ammonia, from
which, by the agency of nitrifying organisms, it is turned into
nitrates and made available for the use of plants. Humus is able to
retain phosphoric acid, potash, ammonia and other bases. So important
were the functions of humus considered at one time that on this Thaer
built his "humus theory," which was, in effect, that, if humus was
supplied to the soil, plants required nothing more. This was based,
however, on the erroneous belief that the carbon, of which the bulk of
the plant consists, was derived from the humus of the soil, and not,
as we now know it to be, from the carbonic acid of the atmosphere.
This theory was in turn replaced by the "mineral theory" of Liebig,
and then both of them by the "nitrogen theory" of Lawes and Gilbert.
We pass next to review, in the light of the foregoing, the manures in
common use at the present day.
Manures, as already stated, may be variously classified according to the
materials they are made from, the constituents which they chiefly
supply, or the uses to which they are put. But, except with certain few
manures, such as nitrate of soda, sulphate of ammonia and potash salts,
which are used purely for one particular purpose, it is impossible to
make any definite classification of manures, owing to the fact that the
majority of them serve more than one purpose, and contain more than one
fertilizing constituent of value. It is only on broad lines, therefore,
that any division can be framed. Between so-called "natural" manures
like farm-yard manure, seaweed, wool waste, shoddy, bones, &c., which
undergo no particular artificial preparation, and manufactured manures
like superphosphate, dissolved bones, and other artificially prepared
materials, there may, however, be a distinction drawn, as also between
these and such materials as are imported and used without further
preparation, e.g. nitrate of soda, kainit, &c. On the whole, the best
classification to attempt is that according to the fertilizing
constituents which each principally supplies, and this will be adopted
here, with the necessary qualifications.