Neutralization (chemistry)

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https://en.wikipedia.org/wiki/Neutralization_(chemistry) 

Animation of a strong acid–strong base neutralization titration (using phenolphthalein). The equivalence point is marked in red.

In chemistry, neutralization or neutralisation (see spelling differences) is a chemical reaction in which acid and a base react with an equivalent quantity of each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution. The pH of the neutralized solution depends on the acid strength of the reactants.

Meaning of "neutralization"

In the context of a chemical reaction the term neutralization is used for a reaction between an acid and a base or alkali. Historically, this reaction was represented as

acid + base (alkali) → salt + water

For example:

HCl + NaOH → NaCl + H₂O

The statement is still valid as long as it is understood that in an aqueous solution the substances involved are subject to dissociation, which changes the ionization state of the substances. The arrow sign, →, is used because the reaction is complete, that is, neutralization is a quantitative reaction. A more general definition is based on Brønsted–Lowry acid–base theory.

AH + B → A + BH

Electrical charges are omitted from generic expressions such as this, as each species A, AH, B, or BH may or may not carry an electrical charge. Neutralization of sulfuric acid provides a specific example. Two partial neutralization reactions are possible in this instance.

H₂SO₄ + OH⁻ → HSO⁻
₄ + H₂O

HSO⁻
₄ + OH⁻ → SO²⁻
₄ + H₂O

Overall: H₂SO₄ + 2 OH⁻ → SO²⁻
₄+ 2 H₂O

After an acid AH has been neutralized there are no molecules of the acid (or hydrogen ions produced by dissociation of the molecule) left in solution.

When an acid is neutralized the amount of base added to it must be equal to the amount of acid present initially. This amount of base is said to be the equivalent amount. In a titration of an acid with a base, the point of neutralization can also be called the equivalence point. The quantitative nature of the neutralization reaction is most conveniently expressed in terms of the concentrations of acid and alkali. At the equivalence point:

volume (acid) × concentration (H⁺ ions from dissociation) = volume (base) × concentration (OH⁻ ions)

In general, for an acid AH_n at concentration c₁ reacting with a base B(OH)_m at concentration c₂ the volumes are related by:

n v₁ c₁ = m v₂ c₂

An example of a base being neutralized by an acid is as follows.

Ba(OH)₂ + 2 H⁺ → Ba²⁺ + 2 H₂O

The same equation relating the concentrations of acid and base applies. The concept of neutralization is not limited to reactions in solution. For example, the reaction of limestone with acid such as sulfuric acid is also a neutralization reaction.

[Ca,Mg]CO₃(s) + H₂SO₄(aq) → (Ca²⁺, Mg²⁺)(aq) + SO²⁻
₄(aq) + CO₂(g) + H₂O

Such reactions are important in soil chemistry.

Strong acids and strong bases

A strong acid is one that is fully dissociated in aqueous solution. For example, hydrochloric acid, HCl, is a strong acid.

HCl(aq) → H⁺(aq) + Cl⁻(aq)

A strong base is one that is fully dissociated in aqueous solution. For example, sodium hydroxide, NaOH, is a strong base.

NaOH(aq) → Na⁺(aq) + OH⁻(aq)

Therefore, when a strong acid reacts with a strong base the neutralization reaction can be written as

H⁺ + OH⁻ → H₂O

For example, in the reaction between hydrochloric acid and sodium hydroxide the sodium and chloride ions, Na⁺ and Cl⁻ take no part in the reaction. The reaction is consistent with the Brønsted–Lowry definition because in reality the hydrogen ion exists as the hydronium ion, so that the neutralization reaction may be written as

H₃O⁺ + OH⁻ → H₂O + H₂O

When a strong acid is neutralized by a strong base there are no excess hydrogen ions left in the solution. The solution is said to be neutral as it is neither acidic nor alkaline. The pH of such a solution is close to a value of 7; the exact pH value is dependent on the temperature of the solution.

Neutralization is an exothermic reaction. The standard enthalpy change for the reaction H⁺ + OH⁻ → H₂O is −57.30 kJ/mol.

Quantitative treatment

The term fully dissociated is applied to a solute when the concentration of undissociated solute is below the detection limits, that is, when the undissociated solute's concentration is too low to measured. Quantitatively, this is expressed as log K < −2, or in some texts log K < −1.76. This means that the value of the dissociation constant cannot be obtained from experimental measurements. The value can, however, be estimated theoretically. For example the value of log K ≈ −6 has been estimated for hydrogen chloride in aqueous solution at room temperature. A chemical compound may behave as a strong acid in solution when its concentration is low and as a weak acid when its concentration is very high. Sulfuric acid is an example of such a compound.

Weak acids and strong bases

A weak acid HA is one that does not dissociate fully when it is dissolved in water. Instead an equilibrium mixture is formed:

HA + H₂O ⇌ H₃O⁺ + A⁻

Acetic acid is an example of a weak acid. The pH of the neutralized solution resulting from

HA + OH⁻ → H₂O + A⁻

is not close to 7, as with a strong acid, but depends on the acid dissociation constant, K_a, of the acid. The pH at the end-point or equivalence point in a titration may be calculated as follows. At the end-point the acid is completely neutralized so the analytical hydrogen ion concentration, T_H, is zero and the concentration of the conjugate base, A⁻, is equal to the analytical or formal concentration T_A of the acid: [A⁻] = T_A. When a solution of an acid, HA, is at equilibrium, by definition the concentrations are related by the expression

[A⁻][H⁺] = K_a [HA]; pK_a = −log K_a

The solvent (e.g. water) is omitted from the defining expression on the assumption that its concentration is very much greater than the concentration of dissolved acid, [H₂O] ≫ T_A. The equation for mass-balance in hydrogen ions can then be written as

T_H = [H⁺] + [A⁻][H⁺]/K_a − K_w/[H⁺]

Titration curves for addition of a strong base to a weak acid with pK_a of 4.85. The curves are labelled with the concentration of the acid.

where K_w represents the self-dissociation constant of water. Since K_w = [H⁺][OH⁻], the term K_w/[H⁺] is equal to [OH⁻], the concentration of hydroxide ions. At neutralization, T_H is zero. After multiplying both sides of the equation by [H⁺], it becomes

[H⁺]² + T_A[H⁺]²/K_a − K_w = 0

and, after rearrangement and taking logarithms,

pH = 1/2 pK_w + 1/2 log (1 + T_A/K_a)

With a dilute solution of the weak acid, the term 1 + T_A/K_a is equal to T_A/K_a to a good approximation. If pK_w = 14,

pH = 7 + (pK_a + log T_A)/2

This equation explains the following facts:

• The pH at the end-point depends mainly on the strength of the acid, pK_a.
• The pH at the end-point is greater than 7 and increases with increasing concentration of the acid, T_A, as seen in the figure.

In a titration of a weak acid with a strong base the pH rises more steeply as the end-point is approached. At the end-point, the slope of the curve of pH with respect to amount of titrant is a maximum. Since the end-point occurs at pH greater than 7, the most suitable indicator to use is one, like phenolphthalein, that changes color at high pH.

Weak bases and strong acids

The situation is analogous to that of weak acids and strong bases.

B + H₃O⁺ ⇌ BH⁺ + H₂O

Amines are examples of weak bases. The pH of the neutralized solution depends on the acid dissociation constant of the protonated base, pK_a, or, equivalently, on the base association constant, pK_b. The most suitable indicator to use for this type of titration is one, such as methyl orange, that changes color at low pH.

Weak acids and weak bases

When a weak acid reacts with an equivalent amount of a weak base,

HA + B ⇌ A⁻ + BH⁺

complete neutralization does not always occur. The concentrations of the species in equilibrium with each other will depend on the equilibrium constant, K, for the reaction, which is defined as follows:

[A⁻][BH⁺] = K [HA][B].

The neutralization reaction can be considered as the difference of the following two acid dissociation reactions

HA ⇌ H⁺ + A⁻  K_a,A = [A⁻][H⁺]/[HA]

BH⁺ ⇌ B + H⁺  K_a,B = [B][H⁺]/[BH⁺]

with the dissociation constants K_a,A and K_a,B of the acids HA and BH⁺, respectively. Inspection of the reaction quotients shows that

K = K_a,A/K_a,B.

A weak acid cannot always be neutralized by a weak base, and vice versa. However, for the neutralization of benzoic acid (K_a,A = 6.5 × 10⁻⁵) with ammonia (K_a,B = 5.6 × 10⁻¹⁰ for ammonium), K = 1.2 × 10⁵ >> 1, and more than 99% of the benzoic acid is converted to benzoate.

Applications

Chemical titration methods are used for analyzing acids or bases to determine the unknown concentration. Either a pH meter or a pH indicator which shows the point of neutralization by a distinct color change can be employed. Simple stoichiometric calculations with the known volume of the unknown and the known volume and molarity of the added chemical gives the molarity of the unknown.

In wastewater treatment, chemical neutralization methods are often applied to reduce the damage that an effluent may cause upon release to the environment. For pH control, popular chemicals include calcium carbonate, calcium oxide, magnesium hydroxide, and sodium bicarbonate. The selection of an appropriate neutralization chemical depends on the particular application.

There are many uses of neutralization reactions that are acid-alkali reactions. A very common use is antacid tablets. These are designed to neutralize excess gastric acid in the stomach (HCl) that may be causing discomfort in the stomach or lower esophagus. This can also be remedied by the ingestion of sodium bicarbonate (NaHCO₃). Sodium bicarbonate is also commonly used to neutralise acid spills in laboratories, as well as acid burns.

In chemical synthesis of nanomaterials, the heat of neutralization reaction can be used to facilitate the chemical reduction of metal precursors.

Also in the digestive tract, neutralization reactions are used when food is moved from the stomach to the intestines. In order for the nutrients to be absorbed through the intestinal wall, an alkaline environment is needed, so the pancreas produce an antacid bicarbonate to cause this transformation to occur.

Another common use, though perhaps not as widely known, is in fertilizers and control of soil pH. Slaked lime (calcium hydroxide) or limestone (calcium carbonate) may be worked into soil that is too acidic for plant growth. Fertilizers that improve plant growth are made by neutralizing sulfuric acid (H₂SO₄) or nitric acid (HNO₃) with ammonia gas (NH₃), making ammonium sulfate or ammonium nitrate. These are salts utilized in the fertilizer.

Industrially, a by-product of the burning of coal, sulfur dioxide gas, may combine with water vapor in the air to eventually produce sulfuric acid, which falls as acid rain. To prevent the sulfur dioxide from being released, a device known as a scrubber gleans the gas from smoke stacks. This device first blows calcium carbonate into the combustion chamber where it decomposes into calcium oxide (lime) and carbon dioxide. This lime then reacts with the sulfur dioxide produced forming calcium sulfite. A suspension of lime is then injected into the mixture to produce a slurry, which removes the calcium sulfite and any remaining unreacted sulfur dioxide.

Christianity and colonialism

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Christianity_and_colonialism

Christianity and colonialism are often closely associated with each other due to the service of Christianity, in its various sects (namely Protestantism, Catholicism and Orthodoxy), as the state religion of the historical European colonial powers, in which Christians likewise made up the majority. Through a variety of methods, Christian missionaries acted as the "religious arms" of the imperialist powers of Europe. According to Edward E. Andrews, Associate Professor of Providence College Christian missionaries were initially portrayed as "visible saints, exemplars of ideal piety in a sea of persistent savagery". However, by the time the colonial era drew to a close in the later half of the 20th century, missionaries were viewed as "ideological shock troops for colonial invasion whose zealotry blinded them", colonialism's "agent, scribe and moral alibi".

In some regions, almost all of a colony's population was forcibly turned away from its traditional belief systems and forcibly turned towards the Christian faith, which colonizers used as a justification for their extermination of adherents of other faiths, their enslavement of natives, and their exploitation of lands and seas.

Background

Christianity is targeted by critics of colonialism because the tenets of the religion were used to justify the actions of the colonists. For example, Toyin Falola asserts that there were some missionaries who believed that "the agenda of colonialism in Africa was similar to that of Christianity". Falola cites Jan H. Boer of the Sudan United Mission as saying, "Colonialism is a form of imperialism based on a divine mandate and designed to bring liberation – spiritual, cultural, economic and political – by sharing the blessings of the Christ-inspired civilization of the West with a people suffering under satanic oppression, ignorance and disease, effected by a combination of political, economic and religious forces that cooperate under a regime seeking the benefit of both ruler and ruled."

Edward Andrews writes:

Historians have traditionally looked at Christian missionaries in one of two ways. The first church historians to catalogue missionary history provided hagiographic descriptions of their trials, successes, and sometimes even martyrdom. Missionaries were thus visible saints, exemplars of ideal piety in a sea of persistent savagery. However, by the middle of the twentieth century, an era marked by civil rights movements, anti-colonialism, and growing secularization, missionaries were viewed quite differently. Instead of godly martyrs, historians now described missionaries as arrogant and rapacious imperialists. Christianity became not a saving grace but a monolithic and aggressive force that missionaries imposed upon defiant natives. Indeed, missionaries were now understood as important agents in the ever-expanding nation-state, or "ideological shock troops for colonial invasion whose zealotry blinded them."

According to Lamin Sanneh, "(m)uch of the standard Western scholarship on Christian missions proceeds by looking at the motives of individual missionaries and concludes by faulting the entire missionary enterprise as being part of the machinery of Western cultural imperialism." As an alternative to this view, Sanneh presents a different perspective arguing that "missions in the modern era have been far more, and far less, than the argument about motives customarily portrayed."

Michael Wood asserts that during the 16th century, it was almost impossible for the indigenous peoples to be considered human beings in their own right, and that the conquistadors brought with them the baggage of "centuries of Ethnocentrism, and Christian monotheism, which espoused one truth, one time and version of reality."

Age of Discovery

Further information: Colonialism, Age of Discovery, and Catholic Church and the Age of Discovery

 

The convent of San Augustin. A mission centre established at Yuriria, Mexico, in 1550

During the Age of Discovery, the Catholic Church inaugurated a major effort to spread Christianity in the New World and to convert the Native Americans and other indigenous people. The missionary effort was a major part of, and a partial justification for the colonial efforts of European powers such as Spain, France and Portugal. The idea of European exploration and Christian expansion were synonymous with each other as European Christians' religious views and settlements in new lands were a way to convert the indigenous peoples. Christian Missions to the indigenous peoples ran hand-in-hand with the colonial efforts of Catholic nations. In the Americas and other colonies in Asia and Africa, most missions were run by religious orders such as the Augustinians, Franciscans, Jesuits and Dominicans.

In both Portugal and Spain, religion was an integral part of the state and Christianization was seen as having both secular and spiritual benefits. Portuguese explorers would propose ideas of venturing into new territories to religious executives, which were approved based on the idea that "honor and glory will befall not only all of Christendom but also … this most sacred See of Peter." Wherever these powers attempted to expand their territories or influence, missionaries would soon follow. By the Treaty of Tordesillas, the two powers divided the world between them into exclusive spheres of influence, trade and colonization. The Roman Catholic world order was challenged by the Netherlands and England. Theoretically, it was repudiated by Grotius's Mare Liberum. Portugal's and Spain's colonial policies were also challenged by the Roman Catholic Church itself. The Vatican founded the Congregatio de Propaganda Fide in 1622 and attempted to separate the churches from the influence of the Iberian kingdoms.

Americas

Jan van Butselaar writes that "for Prince Henry the Navigator and his contemporaries, the colonial enterprise was based on the necessity to develop European commerce and the obligation to propagate the Christian faith."

Christian leaders and Christian doctrines have been accused of justifying and perpetrating violence against Native Americans found in the New World.

Spanish missions

Main article: Spanish missions in the Americas

Adriaan van Oss wrote:

If we had to choose a single, irreducible idea underlying Spanish colonialism in the New World, it would undoubtedly be the propagation of the Catholic faith. Unlike such other European colonizing powers as England or the Netherlands, Spain insisted on converting the natives of the lands it conquered to its state religion. Miraculously, it succeeded. Introduced in the context of Iberian expansionism, Catholicism outlived the empire itself and continues to thrive, not as an anachronistic vestige among the elite, but as a vital current even in remote mountain villages. Catholic Christianity remains the principal colonial heritage of Spain in America. More than any set of economic relationships with the outside world, more even than the language first brought to America's shores in 1492, the Catholic religion continues to permeate Spanish-American culture today, creating an overriding cultural unity which transcends the political and national boundaries dividing the continent.

Diego de Landa, Spanish colonial Bishop of Yucatan and writer of important historical account of the Maya, ordered the burning of thousands Maya sacred and history texts

The Spanish were the first of the future European countries to colonize North and South America. They came into the region predominantly through Cuba and Puerto Rico and into Florida. The Spaniards were committed, by Vatican decree, to convert their New World indigenous subjects to Catholicism. However, often initial efforts (both docile and coerced) were questionably successful, as the indigenous people added Catholicism into their longstanding traditional ceremonies and beliefs. An example of the successful integration of Catholicism into longstanding beliefs is the change in the Incan religion. Spaniards, especially, weaved Catholicism into Incan religious beliefs by altering the Andean religion to align more with Catholic teachings. This religious integration resulted from the idea that the Incan indigenous people were better Catholics than the Europeans who preached to them. The many native expressions, forms, practices, and items of art could be considered idolatry and prohibited or destroyed by Spanish missionaries, military, and civilians. This included religious items, sculptures, and jewelry made of gold or silver, which were melted down before shipment to Spain. This shows the ideology of the Spanish conquerors, who were motivated by God, gold, and glory.

Although the Spanish did not impose their language to the extent they did their religion, some indigenous languages of the Americas evolved into replacing their native tongue with Spanish, and lost to present day tribal members. Priests who understood and could speak the indigenous languages were more efficient in religious conversion when they did evangelize in native languages. It was a collective effort by both groups to form a way of communication with each other as Quechua-speaking officials, and Andean officials learned the Spanish language.

In the early years most mission work was undertaken by the religious orders. Over time it was intended that a normal church structure would be established in the mission areas. The process began with the formation of special jurisdictions, known as apostolic prefectures and apostolic vicariates. These developing churches eventually graduated to regular diocesan status with the appointment of a local bishop. After decolonization, this process increased in pace as church structures altered to reflect new political-administrative realities.

Ralph Bauer describes the Franciscan missionaries as having been "unequivocally committed to Spanish imperialism, condoning the violence and coercion of the Conquest as the only viable method of bringing American natives under the saving rule of Christianity." Jordan writes "The catastrophe of Spanish America's rape at the hands of the Conquistadors remains one of the most potent and pungent examples in the entire history of human conquest of the wanton destruction of one culture by another in the name of religion"

Antonio de Montesinos, a Dominican friar on the island of Hispaniola, was the first member of the clergy to publicly denounce all forms of enslavement and oppression of the indigenous peoples of the Americas. Theologians such as Francisco de Vitoria and Bartolomé de las Casas drew up theological and philosophical bases for the defense of the human rights of the colonized native populations, thus creating the basis of international law, regulating the relationships between nations.

The Native Americans only gave way to the force of the European after they were overcome with the diseases the Europeans had spread. The Evangelization of the natives in the Americas began with private colonization. The Crown tried to establish rules to protect the natives against any unjust war of conquest. The Spanish could start a war against those who rejected the kings authority and who were aware and also rejected Christianity. There was a doctrine developed that allowed the conquest of natives if they were uncivilized.

Friars and Jesuits learned native languages instead of teaching the natives Spanish because they were trying to protect them from the colonists’ negative influences. In addition, the missionaries felt it was important to show the positive aspects of the new religion to the natives after the epidemics and harsh conquest that had just occurred.

French missions

Main articles: French colonization of the Americas, France Équinoxiale, and Protectorate of missions

The Jesuit order (the Society of Jesus) established missions among the Iroquois in North America by the 1650s–1660s. Their success in the study of indigenous languages Was appreciated by the Iroquois, who helped them expand into the Great Lakes region by 1675. Their order was banished from France in 1736, but they did not entirely disappear from North America, and an American diocese was established in 1804.

In the 1830s Marist missionaries from the Catholic Society of Mary promoted missions to various Pacific islands Oceana. The head of the order Friar Jean-Claude Colin and Bishop Jean-Baptiste-François Pompallier worked in close conjunction with the colonized imperialism and colony-building program of the French government. Trouble arose in Hawaii, where the local government strongly favored Protestant missionaries from the United States over the Picpusien Fathers, who had established a mission in Honolulu in 1827. Puritanical American missionaries wanted the Catholics expelled until the French Navy arrived in 1839 and issued an ultimatum to tolerate the Catholics.

Jesuit missions

Various missions and initiatives of the Jesuits predated, accompanied and followed western colonization across the world. In Lithuania, since 1579 the Jesuit-founded Vilnius University spearheaded Counterreformation, eradication of indigenous religion and language. At around the same time in China, Korea and Japan Jesuit missions predated western military incursions by a couple of centuries. The incursions were not only ideological but scientific – the Jesuits reformed the Chinese lunisolar calendar in 1645, a change described as "pathological". 17th-century India deserved a mission to study Brahmanical knowledge and Christianizing missions were dispatched to native North Americans. Jesuit missions were documented in biannual Jesuit Relations:

In "Harvest of Souls: The Jesuit Missions and Colonialism in North America, 1632–1650", Carole Blackburn uses the Jesuit Relations to shed light on the dialogue between Jesuit missionaries and the Native peoples of northeastern North America. In 1632 Jesuit missionary Paul Le Jeune, newly arrived at the fort of Quebec, wrote the first of the Relations to his superior in Paris, initiating a series of biannual mission reports that came to be known as the Jesuit Relations. In other writings, Jesuit missionaries in New France preaching to the Amerindians described the indigenous peoples as "savages" and tried to instill European standards of religion and civilization upon them. Jesuit missionaries attempted to culturally transform these people by creating confusion and disturbing their religious order and lifestyles.

Blackburn presents a contemporary interpretation of the 1632–1650 Relations, arguing that they are colonizing texts in which the Jesuits use language, imagery, and forms of knowledge to legitimize relations of inequality with the Huron and Montagnais. ... Blackburn shows that this resulted in the displacement of much of the content of the message and demonstrates that the Native people's acts of resistance took up and transformed aspects of the Jesuits' teachings in ways that subverted their authority.

In 1721, Jesuit Ippolito Desideri tried to Christianize Tibetans but permission from the Order was not granted.

Jesuits themselves participated in economic colonization, founding and operating vast ranches in Peru and Argentina to this day. Jesuit reductions were socialist theocratic settlements for indigenous people specifically in the Rio Grande do Sul area of Brazil, Paraguay and neighbouring Argentina in South America, established by the Jesuit Order early in the 17th century and wound up in the 18th century with the banning of the order in several European countries.

A large body of scientific work exists examining entanglements between Jesuit missions, western science emanating from Jesuit-founded universities, colonization and globalization. Since the global Jesuit network grew so large as to necessitate direct connections between branches without passing though Vatican, Jesuit order can be seen as one of the earliest examples of global organizations and globalization.

Canada

In 2021, unmarked graves of indigenous children were found at Marieval Indian Residential School and Kamloops Indian Residential School, part of the Canadian Indian residential school system.

The majority (67 percent) of residential schools were run by the Catholic Church, with the remaining 33 percent including the Anglican, United, and Presbyterian Church.

Japan

First Jesuit missionaries arrived in Kyushu in 1542 from Portugal and brought gunpowder with them. Francis Xavier arrived in 1550. Father Xavier was a pioneer in the Christian colonization of Japanese culture as he attempted to understand the Japanese language to build up fidelity in the new Japanese converts. The success of his evangelizing came from gathering individuals and families rather than mass preaching. These preachings lead to baptisms and successful missions in Japan. Jesuit missionaries were also favorable of Japan as a mission destination rather than other destinations due to the highly civilized society of the Japanese people. Father Xavier admired the Japanese for their 'houses and palaces,' 'civilization,' and its 'luxuries.'

In the late 1580s, Jesuit missionary and operative Gaspar Coelho attempted to create an axis of Christian converts among southern feudatory lords who would support an armed Christian takeover of Japan. Arms were to be procured from Portuguese colonial outposts in South and Southeast Asia, however the plan was detected by the Toyotomi government and came to nothing.

Later, in 1596, a Spanish Manila galleon became wrecked on the coast of Shikoku. Its pilot, upon being interviewed, insinuated to the Japanese authorities that it was the Spanish modus operandi to subvert native societies from within via mass Christian conversion prior to conquest. Toyotomi Hideyoshi, chief advisor to the Emperor, commenced the first lethal suppression of Christianity at this time.

In 1825, the military scholar Aizawa Seishisai published a series of essays to be presented to the Tokugawa government on, among other things, the threat to Japan's sovereignty posed by Christianity. In it, he suggested that the European and American powers used Christianity as a cultural weapon by which native populations could be turned on their own governments in order to facilitate conquest and colonization. The text discussed directly the Toyotomi-era encounters with the Jesuits, and warned that the countries of Asia, particularly Japan and China, had become geographically and politically isolated as the last surviving nations maintaining polities not based on Abrahamic religion.

India

The first converts to Christianity in Goa were native Goan women who married Portuguese men that arrived with Afonso de Albuquerque during the Portuguese conquest of Goa in 1510.

Christian maidens of Goa meeting a Portuguese nobleman seeking a wife, from the Códice Casanatense (c. 1540)

Missionaries of various religious orders (Franciscans, Dominicans, Jesuits, Augustinians, etc.) were sent from Portugal to Goa with the goal of fulfilling the papal bull Romanus Pontifex, which granted the patronage of the propagation of the Christian faith in Asia to the Portuguese. To promote assimilation of the native Goans with the Portuguese people, the Portuguese authorities in Goa supported these missionaries. The rapid rise of converts in Goa was mostly the result of Portuguese economic and political control over the Hindus, who were vassals of the Portuguese crown. By the 1580s, the total population of Goa was about 60,000 with an estimated Hindu population then about a third or 20,000. The Goa Inquisition was an extension of the Portuguese Inquisition in Portuguese India. Its objective was to enforce Catholic Orthodoxy and allegiance to the Apostolic See of Rome (Pontifex). The inquisition primarily focused on the New Christians accused of secretly practicing their former religions, and Old Christians accused of involvement in the Protestant Revolution of the 16th century. It was established in 1560, briefly suppressed from 1774 to 1778, continued thereafter until it was finally abolished in 1812.

Over 90% of Goans in the Velhas Conquistas became Catholic by the early 1700s. Xenddi was a discriminatory religious tax imposed on the Goan Hindu minority by the colonial era Portuguese Christian government in Goa, Daman and Diu in 1704. It was similar to the discriminatory Jizya religious tax imposed on Hindus by Muslim rulers in the region. In its initial formulation, the tax was introduced with the pretext that Hindus did not own any land in Goa and only the Christians did. Land revenues were paid by the Goan Catholics in Goa, and the regional Church argued that Xenddi tax would make Hindus pay their fair share. The tax and the tax rate on Hindus evolved to be an abusive form of religious discrimination. According to Rene Berendse, the Xenddi tax was considered to be an example of religious intolerance by the neighboring Mahratta Confederacy, and its local leader Govind Das Pant made abolishment of the discriminatory tax against the Hindus as a condition for a mutual armistice agreement. The Goan government initially refused, stating that the Xenddi tax was a matter of the Church, which the Portuguese state cannot interfere in. Expanded to all of Portuguese colonies in the Indian subcontinent by 1705, the Xenddi tax was abolished in 1840, with J.J. Lopes de Lima – the Governor General of Goa declaring it to be "cruel, hateful tribute and ridiculous capitation tax" on Hindus.

In India, the British missionaries were often in conflict with British administrators and businessmen. Missionaries had moderate success among the scheduled classes. In French-controlled Vietnam, and a Japanese-controlled Korea, the Christian missionaries had significant success in terms of membership.

Christianity had a more subtle effect, reaching far beyond the converted population to potential modernizers. The introduction of European medicine was especially important, as well as the introduction of European political practices and ideals such as religious liberty, mass education, mass printing, newspapers, voluntary organizations, colonial reforms, and especially liberal democracy. However, more recent research finds no significant relationship between Protestant missions and the development of democracy.

Africa

North German missionary school in Togo, 1899

Although there were some earlier small-scale efforts, the major missionary activities from Europe and North America came late in the 19th century, during the Scramble for Africa.

Christian evangelists were intimately involved in the colonial process in southern Africa. The missionaries discovered increasingly that the medical and educational services they could provide were highly welcome to Africans who were not responsive to theological appeals. When Christian missionaries came to Africa, some native peoples were very hostile and not accepting of the missionaries in Africa. During the Scramble for Africa, there was a realization that African regions had valuable resources from which Western culture could profit. Christianity was a disguise for Western colonization in those areas to take valuable resources from the native African land. Despite the rush to Africa for its goods, in the book A History of Africa by J.D. Fage, he states, "Mid-and late-nineteenth-century Europeans were generally convinced that their Christian, scientific and industrial society was intrinsically far superior to anything that Africa had produced." The exploitation of natural resources can contribute to the hostility of African natives towards European colonizers. Even though there were some Christian missionaries that went about colonizing the native Africans in unchristian ways there were some missionaries who were truly devoted to colonizing through peaceful means and truly thought that the people of Africa needed to be taught that Jesus was their Savior.

David Livingstone (1813–1873), a Scottish missionary, became world-famous in the Anglophone world. He worked after 1840 north of the Orange River with the London Missionary Society, as an explorer, missionary and writer. He became one of the most popular British heroes of the late 19th-century Victorian era. He had a mythical status that operated on a number of interconnected levels: Protestant missionary martyr, inspirational story of rising from the poor, scientific investigator and explorer, imperial reformer, and an anti-slavery crusader.

In the late 19th century, Mwanga II, kabaka of the kingdom of Buganda, was in conflict with Christian missionaries due to fears of cultural and political subversion with an eye to the ultimate conquest of Buganda by the British. In 1886, he began a campaign of violent suppression of Christianity. The British quickly moved to dethrone him and supported an armed uprising by Christian converts and local Muslims. He was swiftly defeated by a force under his half-brother, a Christian convert, at Mengo hill in 1888. After a period of political unrest, Mwanga agreed to surrender his temporal powers to the Imperial British East Africa Company in exchange for being allowed to nominally return to the throne. Thereafter the kingdom of Buganda became essentially a British protectorate and was politically defunct. Mwanga himself ultimately died a Christian.

French Catholic missionaries worked in the extensive colonial holdings in Africa. However, in independent Ethiopia (Abyssinia), four French Franciscan sisters arrived in 1897, summoned there by the Capuchin missionaries. By 1925, they were very well-established, running an orphanage, a dispensary, a leper colony and 10 schools with 350 girl students. The schools were highly attractive to upper-class Ethiopians.

In French West Africa in the 1930s, a serious debate emerged between the French missionaries on the one side, and the upper-class local leadership that had been attending French schools in preparation for eventual leadership. Many of them had become Marxists, and French officials worried that they were creating their own Frankenstein monster. The French shifted priorities to set up rural schools for the poor lower classes, and an effort to support indigenous African culture and produce reliable collaborators with the French regime, instead of far-left revolutionaries seeking to overthrow it. The French plan to work through local traditional chiefs. For the same reason they also set up Koranic schools and Muslim areas. The traditional chiefs would be paid larger salaries and have charge of tax collection, local courts, military recruiting, and obtaining forced labor for public works projects. The government's program seemed a threat to the ambitions of the Marxist locals and they wanted them closed. The Marxist incited labor strikes, and encouraged immigration to British territories. When the far-right Petain government came to power in Vichy, France in 1940, a high priority was to remove the educated Marxist elite from any positions of authority in French West Africa.

Long-term impact

Walter Rodney a Marxist historian based at the University of Dar es Salaam in Tanzania developed an influential attack on Europe in How Europe Underdeveloped Africa (1972). He mentioned the missionaries:

The Christian missionaries were much part of the colonizing forces as were the explorers, traders and soldiers. There may be room for arguing whether in a given colony the missionaries brought other colonialist forces or vice versa, but there is no doubting the fact that missionaries were agents of colonialism in the practical sense whether or not they saw themselves in that light.

According to Heather Sharkey, the real impact of the activities of the missionaries is still a topic open to debate in academia today. Sharkey asserted that "the missionaries played manifold roles in colonial Africa and stimulated forms of cultural, political and religious change." Historians still debate the nature of their impact and question their relation to the system of European colonialism in the continent. Sharkey noted that the missionaries provided crucial social services such as modern education and health care that would have otherwise not been available. Sharkey said that, in societies that were traditionally male-dominated, female missionaries provided women in Africa with health care knowledge and basic education. Conversely, it has been argued that Christianity played a central role in colonial efforts, allowing Christian missionaries to "colonize the conscience and consciousness" of Africans, thus instilling the belief that any non-Christian spiritual ideas are inferior to Christianity, echoing the colonial hierarchical view of culture.

A Pew Center study about religion and education around the world in 2016, found that "there is a large and pervasive gap in educational attainment between Muslims and Christians in sub-Saharan Africa" as Muslim adults in this region are far less educated than their Christian counterparts, with scholars suggesting that this gap is due to the educational facilities that were created by Christian missionaries during the colonial era for fellow believers.

A major contribution of the Christian missionaries in Africa was better health care of the people through hygiene and introducing and distributing the soap, and "cleanliness and hygiene became an important marker of being identified as a Christian".

Current Christian perspectives

Pope Francis, a Jesuit, has frequently criticised the colonialism and neocolonialism of the Christian nations of the Global North, referring to colonialism as "blasphemy against God" and saying that "many grave sins were committed against the native peoples of America in the name of God." Speaking with hindsight and on the basis of current theology, Francis said: "No actual or established power has the right to deprive peoples of the full exercise of their sovereignty." He also speaks of "the new colonialism [which] takes on different faces. At times it appears as the anonymous influence of mammon: corporations, loan agencies, certain 'free trade' treaties, and the imposition of measures of 'austerity' which always tighten the belt of workers and the poor."

Tillage

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Tillage

 

Cultivating after an early rain

Tillage is the agricultural preparation of soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shoveling, picking, mattock work, hoeing, and raking. Examples of draft-animal-powered or mechanized work include ploughing (overturning with moldboards or chiseling with chisel shanks), rototilling, rolling with cultipackers or other rollers, harrowing, and cultivating with cultivator shanks (teeth).

Tillage that is deeper and more thorough is classified as primary, and tillage that is shallower and sometimes more selective of location is secondary. Primary tillage such as ploughing tends to produce a rough surface finish, whereas secondary tillage tends to produce a smoother surface finish, such as that required to make a good seedbed for many crops. Harrowing and rototilling often combine primary and secondary tillage into one operation.

"Tillage" can also mean the land that is tilled. The word "cultivation" has several senses that overlap substantially with those of "tillage". In a general context, both can refer to agriculture. Within agriculture, both can refer to any kind of soil agitation. Additionally, "cultivation" or "cultivating" may refer to an even narrower sense of shallow, selective secondary tillage of row crop fields that kills weeds while sparing the crop plants.

Definitions

Primary tillage loosens the soil and mixes in fertilizer or plant material, resulting in soil with a rough texture.

Secondary tillage produces finer soil and sometimes shapes the rows, preparing the seed bed. It also provides weed control throughout the growing season during the maturation of the crop plants, unless such weed control is instead achieved with low-till or no-till methods involving herbicides.

• The seedbed preparation can be done with harrows (of which there are many types and subtypes), dibbles, hoes, shovels, rotary tillers, subsoilers, ridge- or bed-forming tillers, rollers, or cultivators.
• The weed control, to the extent that it is done via tillage, is usually achieved with cultivators or hoes, which disturb the top few centimeters of soil around the crop plants but with minimal disturbance of the crop plants themselves. The tillage kills the weeds via two mechanisms: uprooting them, burying their leaves (cutting off their photosynthesis), or a combination of both. Weed control both prevents the crop plants from being outcompeted by the weeds (for water and sunlight) and prevents the weeds from reaching their seed stage, thus reducing future weed population aggressiveness.

History

Tilling with Hungarian Grey cattle

Tilling was first performed via human labor, sometimes involving slaves. Hoofed animals could also be used to till soil by trampling, in addition to pigs, whose natural instincts are to root the ground regularly if allowed to. The wooden plow was then invented. It could be pulled with human labor, or by mule, ox, elephant, water buffalo, or a similar sturdy animal. Horses are generally unsuitable, though breeds such as the Clydesdale were bred as draft animals.

Tilling could at times be very labor-intensive. This aspect is discussed in the 16th-century French agronomic text written by Charles Estienne:

A rawe, rough, and tough soile is hard to till, and will neither bring forth corne, nor any other thing without great labour, howsoever the seasons be temperat in moisture and dryness ... you must labour it most exquisitely, harrow it and manure it verie oft with great store of dung, so you shall make it better ... but especially desire that they may not be watered with raine, for water is as good as poyson to them.

The popularity of tillage as an agricultural technique in early modern times had to do with theories about plant biology proposed by European thinkers. In 1731, English writer Jethro Tull published the book "Horse-Hoeing Husbandry: An Essay on the Principles of Vegetation and Tillage," which argued that soil needed to be pulverized into fine powder for plants to make use of it. Tull believed that, since water, air, and heat were clearly not the primary substance of a plant, plants were made of earth, and thus had to consume very small pieces of earth as food. Tull wrote that each subsequent tillage of the soil would increase its fertility, and that it was impossible to till the soil too much. However, scientific observation has shown that the opposite is true; tillage causes soil to lose structural qualities that allow plant roots, water, and nutrients to penetrate it, accelerates soil loss by erosion, and results in soil compaction. 

The steel plow allowed farming in the American Midwest, where tough prairie grasses and rocks caused trouble. Soon after 1900, the farm tractor was introduced, which made modern large-scale agriculture possible. However, the destruction of the prairie grasses and tillage of the fertile topsoil of the American Midwest caused the Dust Bowl, in which the soil was blown away and stirred up into dust storms that blackened the sky. This prompted re-consideration of tillage techniques, but in the United States, as of 2019 3 trillion pounds of soil are still lost to erosion and adoption of improved techniques is still not widespread.

Types

Primary and secondary tillage

Primary tillage is usually conducted after the last harvest, when the soil is wet enough to allow plowing but also allows good traction. Some soil types can be plowed dry. The objective of primary tillage is to attain a reasonable depth of soft soil, incorporate crop residues, kill weeds, and to aerate the soil. Secondary tillage is any subsequent tillage, to incorporate fertilizers, reduce the soil to a finer tilth, level the surface, or control weeds.

Reduced tillage

Reduced tillage leaves between 15 and 30% crop residue cover on the soil or 500 to 1000 pounds per acre (560 to 1100 kg/ha) of small grain residue during the critical erosion period. This may involve the use of a chisel plow, field cultivators, or other implements. See the general comments below to see how they can affect the amount of residue.

Intensive tillage

Intensive tillage leaves less than 15% crop residue cover or less than 500 pounds per acre (560 kg/ha) of small grain residue. This type of tillage is often referred to as conventional tillage, but as conservational tillage is now more widely used than intensive tillage (in the United States), it is often not appropriate to refer to this type of tillage as conventional. Intensive tillage often involves multiple operations with implements such as a mold board, disk, or chisel plow. After this, a finisher with a harrow, rolling basket, and cutter can be used to prepare the seed bed. There are many variations.

Conservation tillage

Conservation tillage leaves at least 30% of crop residue on the soil surface, or at least 1,000 lb/ac (1,100 kg/ha) of small grain residue on the surface during the critical soil erosion period. This slows water movement, which reduces the amount of soil erosion. Additionally, conservation tillage has been found to benefit predatory arthropods that can enhance pest control. Conservation tillage also benefits farmers by reducing fuel consumption and soil compaction. By reducing the number of times the farmer travels over the field, significant savings in fuel and labor are made.

Conservation tillage is used on over 370 million acres, mostly in South America, Oceania and North America. In most years since 1997, conservation tillage was used in US cropland more than intensive or reduced tillage.

However, conservation tillage delays warming of the soil due to the reduction of dark earth exposure to the warmth of the spring sun, thus delaying the planting of the next year's spring crop of corn.

• No-till – plows, disks, et cetera are not used. Aims for 100% ground cover.
• Strip-till – Narrow strips are tilled where seeds will be planted, leaving the soil in between the rows untilled.
• Mulch-till - Soil is covered with mulch to conserve heat and moisture. 100% soil disturbance.
• Rotational tillage – Tilling the soil every two years or less often (every other year, or every third year, etc.).
• Ridge-till

Zone tillage

Zone tillage is a form of modified deep tillage in which only narrow strips are tilled, leaving soil in between the rows untilled. This type of tillage agitates the soil to help reduce soil compaction problems and to improve internal soil drainage. It is designed to only disrupt the soil in a narrow strip directly below the crop row. In comparison to no-till, which relies on the previous year's plant residue to protect the soil and aids in postponement of the warming of the soil and crop growth in Northern climates, zone tillage produces a strip approximately five inches wide that simultaneously breaks up plow pans, assists in warming the soil and helps to prepare a seedbed. When combined with cover crops, zone tillage helps replace lost organic matter, slows the deterioration of the soil, improves soil drainage, increases soil water and nutrient holding capacity, and allows necessary soil organisms to survive.

It has been successfully used on farms in the Midwest and West of the USA for over 40 years, and is currently used on more than 36% of the U.S. farmland. Some specific states where zone tillage is currently in practice are Pennsylvania, Connecticut, Minnesota, Indiana, Wisconsin, and Illinois.

Its use in the USA's Northern Corn Belt states lacks consistent yield results; however, there is still interest in deep tillage within agriculture. In areas that are not well-drained, deep tillage may be used as an alternative to installing more expensive tile drainage.

Effects

Rice tillage. Valencian Museum of Ethnology.

Positive

Plowing:

• Loosens and aerates the top layer of soil or horizon A, which facilitates planting the crop.
• Helps mix harvest residue, organic matter (humus), and nutrients evenly into the soil.
• Mechanically destroys weeds.
• Dries the soil before seeding (in wetter climates, tillage aids in keeping the soil drier).
• When done in autumn, helps exposed soil crumble over winter through frosting and defrosting, which helps prepare a smooth surface for spring planting.
• Can reduce infestations of slugs, cut worms, army worms, and harmful insects as they are attracted by leftover residues from former crops.
• Reduces the risk of crop diseases which can be harbored in surface residues.

Negative

A Kenyan farmer holding tilled soil

• Dries the soil before seeding.
• Soil loses nutrients, like nitrogen and fertilizer, and its ability to store water.
• Decreases the water infiltration rate of soil. (Results in more runoff and erosion as the soil absorbs water more slowly than before)
• Tilling the soil results in dislodging the cohesiveness of the soil particles, thereby inducing erosion.
• Chemical runoff.
• Reduces organic matter in the soil.
• Reduces microbes, earthworms, ants, etc.
• Destroys soil aggregates.
• Compaction of the soil, also known as a tillage pan.
• Eutrophication (nutrient runoff into a body of water).

Archaeology

Tilling can damage ancient structures such as long barrows. In the UK, half of the long barrows in Gloucestershire and almost all the burial mounds in Essex have been damaged. According to English Heritage in 2003, ploughing with modern powerful tractors had done as much damage in the last six decades as traditional farming did in the previous six centuries.

General comments

• The type of implement makes the most difference, although other factors can have an effect.
• Tilling in absolute darkness (night tillage) might reduce the number of weeds that sprout following the tilling operation by half. Light is necessary to break the dormancy of some weed species' seed, so if fewer seeds are exposed to light during the tilling process, fewer will sprout. This may help reduce the amount of herbicides needed for weed control.
• Greater speeds, when using certain tillage implements (disks and chisel plows), lead to more intensive tillage (i.e., less residue is on the soil surface).
• Increasing the angle of disks causes residues to be buried more deeply. Increasing their concavity makes them more aggressive.
• Chisel plows can have spikes or sweeps. Spikes are more aggressive.
• Percentage residue is used to compare tillage systems because the amount of crop residue affects the soil loss due to erosion.

Alternatives

Modern agricultural science has greatly reduced the use of tillage. Crops can be grown for several years without any tillage through the use of herbicides to control weeds, crop varieties that tolerate packed soil, and equipment that can plant seeds or fumigate the soil without really digging it up. This practice, called no-till farming, reduces costs and environmental change by reducing soil erosion and diesel fuel usage.

Site preparation of forest land

It has been suggested that this section should be split into a new article titled Site preparation of forest land. (discuss) (March 2019)

Site preparation is any of various treatments applied to a site to ready it for seeding or planting. The purpose is to facilitate the regeneration of that site by the chosen method. Site preparation may be designed to achieve, singly or in any combination: improved access, by reducing or rearranging slash, and amelioration of adverse forest floor, soil, vegetation, or other biotic factors. Site preparation is undertaken to ameliorate one or more constraints that would otherwise be likely to thwart the objectives of management. A valuable bibliography on the effects of soil temperature and site preparation on subalpine and boreal tree species has been prepared by McKinnon et al. (2002).

Site preparation is the work that is done before a forest area is regenerated. Some types of site preparation are burning.

Burning

Broadcast burning is commonly used to prepare clearcut sites for planting, e.g., in central British Columbia, and in the temperate region of North America generally.

Prescribed burning is carried out primarily for slash hazard reduction and to improve site conditions for regeneration; all or some of the following benefits may accrue:

a) Reduction of logging slash, plant competition, and humus prior to direct seeding, planting, scarifying or in anticipation of natural seeding in partially cut stands or in connection with seed-tree systems.

b) Reduction or elimination of unwanted forest cover prior to planting or seeding, or prior to preliminary scarification thereto.

c) Reduction of humus on cold, moist sites to favour regeneration.

d) Reduction or elimination of slash, grass, or brush fuels from strategic areas around forested land to reduce the chances of damage by wildfire.

Prescribed burning for preparing sites for direct seeding was tried on a few occasions in Ontario, but none of the burns was hot enough to produce a seedbed that was adequate without supplementary mechanical site preparation.

Changes in soil chemical properties associated with burning include significantly increased pH, which Macadam (1987) in the Sub-boreal Spruce Zone of central British Columbia found persisting more than a year after the burn. Average fuel consumption was 20 to 24 t/ha and the forest floor depth was reduced by 28% to 36%. The increases correlated well with the amounts of slash (both total and ≥7 cm diameter) consumed. The change in pH depends on the severity of the burn and the amount consumed; the increase can be as much as 2 units, a 100-fold change. Deficiencies of copper and iron in the foliage of white spruce on burned clearcuts in central British Columbia might be attributable to elevated pH levels.

Even a broadcast slash fire in a clearcut does not give a uniform burn over the whole area. Tarrant (1954), for instance, found only 4% of a 140-ha slash burn had burned severely, 47% had burned lightly, and 49% was unburned. Burning after windrowing obviously accentuates the subsequent heterogeneity.

Marked increases in exchangeable calcium also correlated with the amount of slash at least 7 cm in diameter consumed. Phosphorus availability also increased, both in the forest floor and in the 0 cm to 15 cm mineral soil layer, and the increase was still evident, albeit somewhat diminished, 21 months after burning. However, in another study in the same Sub-boreal Spruce Zone found that although it increased immediately after the burn, phosphorus availability had dropped to below pre-burn levels within 9 months.

Nitrogen will be lost from the site by burning, though concentrations in remaining forest floor were found by Macadam (1987) to have increased in two out of six plots, the others showing decreases. Nutrient losses may be outweighed, at least in the short term, by improved soil microclimate through the reduced thickness of forest floor where low soil temperatures are a limiting factor.

The Picea/Abies forests of the Alberta foothills are often characterized by deep accumulations of organic matter on the soil surface and cold soil temperatures, both of which make reforestation difficult and result in a general deterioration in site productivity; Endean and Johnstone (1974) describe experiments to test prescribed burning as a means of seedbed preparation and site amelioration on representative clear-felled Picea/Abies areas. Results showed that, in general, prescribed burning did not reduce organic layers satisfactorily, nor did it increase soil temperature, on the sites tested. Increases in seedling establishment, survival, and growth on the burned sites were probably the result of slight reductions in the depth of the organic layer, minor increases in soil temperature, and marked improvements in the efficiency of the planting crews. Results also suggested that the process of site deterioration has not been reversed by the burning treatments applied.

Ameliorative intervention

Slash weight (the oven-dry weight of the entire crown and that portion of the stem less than four inches in diameter) and size distribution are major factors influencing the forest fire hazard on harvested sites. Forest managers interested in the application of prescribed burning for hazard reduction and silviculture, were shown a method for quantifying the slash load by Kiil (1968). In west-central Alberta, he felled, measured, and weighed 60 white spruce, graphed (a) slash weight per merchantable unit volume against diameter at breast height (dbh), and (b) weight of fine slash (<1.27 cm) also against dbh, and produced a table of slash weight and size distribution on one acre of a hypothetical stand of white spruce. When the diameter distribution of a stand is unknown, an estimate of slash weight and size distribution can be obtained from average stand diameter, number of trees per unit area, and merchantable cubic foot volume. The sample trees in Kiil's study had full symmetrical crowns. Densely growing trees with short and often irregular crowns would probably be overestimated; open-grown trees with long crowns would probably be underestimated.

The need to provide shade for young outplants of Engelmann spruce in the high Rocky Mountains is emphasized by the U.S. Forest Service. Acceptable planting spots are defined as microsites on the north and east sides of down logs, stumps, or slash, and lying in the shadow cast by such material. Where the objectives of management specify more uniform spacing, or higher densities, than obtainable from an existing distribution of shade-providing material, redistribution or importing of such material has been undertaken.

Access

Site preparation on some sites might be done simply to facilitate access by planters, or to improve access and increase the number or distribution of microsites suitable for planting or seeding.

Wang et al. (2000) determined field performance of white and black spruces 8 and 9 years after outplanting on boreal mixedwood sites following site preparation (Donaren disc trenching versus no trenching) in 2 plantation types (open versus sheltered) in southeastern Manitoba. Donaren trenching slightly reduced the mortality of black spruce but significantly increased the mortality of white spruce. Significant difference in height was found between open and sheltered plantations for black spruce but not for white spruce, and root collar diameter in sheltered plantations was significantly larger than in open plantations for black spruce but not for white spruce. Black spruce open plantation had significantly smaller volume (97 cm³) compared with black spruce sheltered (210 cm³), as well as white spruce open (175 cm³) and sheltered (229 cm³) plantations. White spruce open plantations also had smaller volume than white spruce sheltered plantations. For transplant stock, strip plantations had a significantly higher volume (329 cm³) than open plantations (204 cm³). Wang et al. (2000) recommended that sheltered plantation site preparation should be used.

Mechanical

Up to 1970, no "sophisticated" site preparation equipment had become operational in Ontario, but the need for more efficacious and versatile equipment was increasingly recognized. By this time, improvements were being made to equipment originally developed by field staff, and field testing of equipment from other sources was increasing.

According to J. Hall (1970), in Ontario at least, the most widely used site preparation technique was post-harvest mechanical scarification by equipment front-mounted on a bulldozer (blade, rake, V-plow, or teeth), or dragged behind a tractor (Imsett or S.F.I. scarifier, or rolling chopper). Drag type units designed and constructed by Ontario's Department of Lands and Forests used anchor chain or tractor pads separately or in combination, or were finned steel drums or barrels of various sizes and used in sets alone or combined with tractor pad or anchor chain units.

J. Hall's (1970) report on the state of site preparation in Ontario noted that blades and rakes were found to be well suited to post-cut scarification in tolerant hardwood stands for natural regeneration of yellow birch. Plows were most effective for treating dense brush prior to planting, often in conjunction with a planting machine. Scarifying teeth, e.g., Young's teeth, were sometimes used to prepare sites for planting, but their most effective use was found to be preparing sites for seeding, particularly in backlog areas carrying light brush and dense herbaceous growth. Rolling choppers found application in treating heavy brush but could be used only on stone-free soils. Finned drums were commonly used on jack pine–spruce cutovers on fresh brushy sites with a deep duff layer and heavy slash, and they needed to be teamed with a tractor pad unit to secure good distribution of the slash. The S.F.I. scarifier, after strengthening, had been "quite successful" for 2 years, promising trials were under way with the cone scarifier and barrel ring scarifier, and development had begun on a new flail scarifier for use on sites with shallow, rocky soils. Recognition of the need to become more effective and efficient in site preparation led the Ontario Department of Lands and Forests to adopt the policy of seeking and obtaining for field testing new equipment from Scandinavia and elsewhere that seemed to hold promise for Ontario conditions, primarily in the north. Thus, testing was begun of the Brackekultivator from Sweden and the Vako-Visko rotary furrower from Finland.

Mounding

Site preparation treatments that create raised planting spots have commonly improved outplant performance on sites subject to low soil temperature and excess soil moisture. Mounding can certainly have a big influence on soil temperature. Draper et al. (1985), for instance, documented this as well as the effect it had on root growth of outplants (Table 30).

The mounds warmed up quickest, and at soil depths of 0.5 cm and 10 cm averaged 10 and 7 °C higher, respectively, than in the control. On sunny days, daytime surface temperature maxima on the mound and organic mat reached 25 °C to 60 °C, depending on soil wetness and shading. Mounds reached mean soil temperatures of 10 °C at 10 cm depth 5 days after planting, but the control did not reach that temperature until 58 days after planting. During the first growing season, mounds had 3 times as many days with a mean soil temperature greater than 10 °C than did the control microsites.

Draper et al.'s (1985) mounds received 5 times the amount of photosynthetically active radiation (PAR) summed over all sampled microsites throughout the first growing season; the control treatment consistently received about 14% of daily background PAR, while mounds received over 70%. By November, fall frosts had reduced shading, eliminating the differential. Quite apart from its effect on temperature, incident radiation is also important photosynthetically. The average control microsite was exposed to levels of light above the compensation point for only 3 hours, i.e., one-quarter of the daily light period, whereas mounds received light above the compensation point for 11 hours, i.e., 86% of the same daily period. Assuming that incident light in the 100–600 µEm‾²s‾1 intensity range is the most important for photosynthesis, the mounds received over 4 times the total daily light energy that reached the control microsites.

Orientation of linear site preparation

With linear site preparation, orientation is sometimes dictated by topography or other considerations, but the orientation can often be chosen. It can make a difference. A disk-trenching experiment in the Sub-boreal Spruce Zone in interior British Columbia investigated the effect on growth of young outplants (lodgepole pine) in 13 microsite planting positions: berm, hinge, and trench in each of north, south, east, and west aspects, as well as in untreated locations between the furrows. Tenth-year stem volumes of trees on south-, east-, and west-facing microsites were significantly greater than those of trees on north-facing and untreated microsites. However, planting spot selection was seen to be more important overall than trench orientation.

In a Minnesota study, the N–S strips accumulated more snow but snow melted faster than on E–W strips in the first year after felling. Snow-melt was faster on strips near the centre of the strip-felled area than on border strips adjoining the intact stand. The strips, 50 feet (15.24 m) wide, alternating with uncut strips 16 feet (4.88 m) wide, were felled in a Pinus resinosa stand, aged 90 to 100 years.