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97-412: Jijel is the administrative and trade center for a region specialising in cork processing, leather tanning and steelmaking . Local crops include citrus and grain . Fishing is also of great importance. Tourists (mainly Algerians) are attracted to Jijel for its landscapes and fine sand beaches. Being a resort town , there are many hotels and restaurants. There are Phoenician tombs nearby. Jijel

194-734: A gas mixture similar to the air, making them behave as authentic "pads," which contributes to the capability of cork to recover after compression. There are about 2,200,000 hectares of cork oak ( Quercus suber ) forest in the Mediterranean basin , the native area of the species. The most extensively managed habitats are in Portugal (34%) and in Spain (27%). Annual production is about 300,000 tons; 49.6% from Portugal, 30.5% from Spain, 5.8% from Morocco , 4.9% from Algeria , 3.5% from Tunisia , 3.1% from Italy , and 2.6% from France . Once

291-440: A trichloroanisole (TCA) free seal, but they also reduce the oxygen transfer rate between the bottle and the atmosphere to almost zero, which can lead to a reduction in the quality of the wine. TCA is the main documented cause of cork taint in wine. However, some in the wine industry say natural cork stoppers are important because they allow oxygen to interact with wine for proper aging, and are best suited for wines purchased with

388-472: A characteristic cellular structure in which the cells have usually a pentagonal or hexagonal shape. The cellular wall consists of a thin, lignin-rich middle lamella (internal primary wall), a thick secondary wall made up from alternating suberin and wax lamella, and a thin tertiary wall of polysaccharides. Some studies suggest that the secondary wall is lignified, and therefore, may not consist exclusively of suberin and waxes. The cells of cork are filled with

485-413: A cork placed inside the neck of a wine bottle is 350-year-old technology, it is logical to explore other more modern and precise methods of keeping wine safe. The study "Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures," conducted by PricewaterhouseCoopers and commissioned by a major cork manufacturer, Amorim , concluded that cork is the most environmentally responsible stopper, in

582-580: A cork stopper. For example, to produce 1,000 cork stoppers 1.5 kg CO 2 are emitted, but to produce the same amount of plastic stoppers 14 kg of CO 2 are emitted and for the same amount of aluminium screw caps 37 kg CO 2 are emitted. The Chinese cork oak is native to East Asia and is cultivated in a limited extent in China; the cork produced is considered inferior to Q. suber and are used to produce agglomerated cork products. The so-called "cork trees" ( Phellodendron ) are unrelated to

679-570: A decline in use as wine-stoppers due to the increase in the use of synthetic alternatives, cork wine-stoppers are making a comeback and currently represent approximately 60% of wine-stoppers in 2016. Because of the cellular structure of cork, it is easily compressed upon insertion into a bottle and will expand to form a tight seal. The interior diameter of the neck of glass bottles tends to be inconsistent, making this ability to seal through variable contraction and expansion an important attribute. However, unavoidable natural flaws, channels, and cracks in

776-643: A dry bulk density (density of soil taking into account voids when dry) between 1.1 and 1.6 g/cm , though the soil particle density is much higher, in the range of 2.6 to 2.7 g/cm . Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic , although fossilized soils are preserved from as far back as the Archean . Collectively the Earth's body of soil

873-423: A massive expansion, particularly due to the development of several cork-based agglomerates. In China , Egypt , Babylon , and Persia from about 3000 BC, cork was already used for sealing containers , fishing equipment, and domestic applications. In ancient Greece (1600 to 1100 years BC) cork was used in footwear , to manufacture a type of sandals attached to the foot by straps, generally leather and with

970-451: A medium for plant growth , making it a critically important provider of ecosystem services . Since soil has a tremendous range of available niches and habitats , it contains a prominent part of the Earth's genetic diversity . A gram of soil can contain billions of organisms, belonging to thousands of species, mostly microbial and largely still unexplored. Soil has a mean prokaryotic density of roughly 10 organisms per gram, whereas

1067-419: A net absorption of oxygen and methane and undergo a net release of carbon dioxide and nitrous oxide . Soils offer plants physical support, air, water, temperature moderation, nutrients, and protection from toxins. Soils provide readily available nutrients to plants and animals by converting dead organic matter into various nutrient forms. Components of a silt loam soil by percent volume A typical soil

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1164-446: A one-year life cycle analysis comparison with plastic stoppers and aluminum screw caps. Soil Soil , also commonly referred to as earth , is a mixture of organic matter , minerals , gases , liquids , and organisms that together support the life of plants and soil organisms . Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil. Soil consists of

1261-549: A pH of 9, plant growth is reduced. High pH results in low micro-nutrient mobility, but water-soluble chelates of those nutrients can correct the deficit. Sodium can be reduced by the addition of gypsum (calcium sulphate) as calcium adheres to clay more tightly than does sodium causing sodium to be pushed into the soil water solution where it can be washed out by an abundance of water. There are acid-forming cations (e.g. hydronium, aluminium, iron) and there are base-forming cations (e.g. calcium, magnesium, sodium). The fraction of

1358-731: A result of a trade-off between toxicity and requirement most nutrients are better available to plants at moderate pH, although most minerals are more soluble in acid soils. Soil organisms are hindered by high acidity, and most agricultural crops do best with mineral soils of pH 6.5 and organic soils of pH 5.5. Given that at low pH toxic metals (e.g. cadmium, zinc, lead) are positively charged as cations and organic pollutants are in non-ionic form, thus both made more available to organisms, it has been suggested that plants, animals and microbes commonly living in acid soils are pre-adapted to every kind of pollution, whether of natural or human origin. In high rainfall areas, soils tend to acidify as

1455-401: A result, layers (horizons) form in the soil profile. The alteration and movement of materials within a soil causes the formation of distinctive soil horizons . However, more recent definitions of soil embrace soils without any organic matter, such as those regoliths that formed on Mars and analogous conditions in planet Earth deserts. An example of the development of a soil would begin with

1552-412: A soil can be said to be developed, and can be described further in terms of color, porosity, consistency, reaction ( acidity ), etc. Water is a critical agent in soil development due to its involvement in the dissolution, precipitation, erosion, transport, and deposition of the materials of which a soil is composed. The mixture of water and dissolved or suspended materials that occupy the soil pore space

1649-399: A soil determines its ability to supply available plant nutrients and affects its physical properties and the health of its living population. In addition, a soil's chemistry also determines its corrosivity , stability, and ability to absorb pollutants and to filter water. It is the surface chemistry of mineral and organic colloids that determines soil's chemical properties. A colloid

1746-477: A sole in cork or leather. In the second century AD, a Greek physician, Dioscorides , noted several medical applications of cork, mainly for hair loss treatment. Nowadays, the majority of people know cork for its use as stoppers in wine bottles . The innovation of using cork as stopper can be traced back to the late 17th century, attributed to Dom Pierre Pérignon . Cork stoppers were adopted in 1729 by Ruinart and in 1973 by Moët et Chandon . Cork presents

1843-737: A solid phase of minerals and organic matter (the soil matrix), as well as a porous phase that holds gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three- state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate , relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (original minerals) interacting over time. It continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion . Given its complexity and strong internal connectedness , soil ecologists regard soil as an ecosystem . Most soils have

1940-481: A suitable material for fishing floats and buoys, as well as handles for fishing rods (as an alternative to neoprene ). Granules of cork can also be mixed into concrete . The composites made by mixing cork granules and cement have lower thermal conductivity, lower density, and good energy absorption. Some of the property ranges of the composites are density (400–1500 kg/m ), compressive strength (1–26 MPa), and flexural strength (0.5–4.0 MPa). As late as

2037-472: A valence of two, converts to (40 ÷ 2) × 1 milliequivalent = 20 milliequivalents of hydrogen ion per 100 grams of dry soil or 20 meq/100 g. The modern measure of CEC is expressed as centimoles of positive charge per kilogram (cmol/kg) of oven-dry soil. Most of the soil's CEC occurs on clay and humus colloids, and the lack of those in hot, humid, wet climates (such as tropical rainforests ), due to leaching and decomposition, respectively, explains

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2134-553: Is 0.04%, but in the soil pore space it may range from 10 to 100 times that level, thus potentially contributing to the inhibition of root respiration. Calcareous soils regulate CO 2 concentration by carbonate buffering , contrary to acid soils in which all CO 2 respired accumulates in the soil pore system. At extreme levels, CO 2 is toxic. This suggests a possible negative feedback control of soil CO 2 concentration through its inhibitory effects on root and microbial respiration (also called soil respiration ). In addition,

2231-603: Is a measure of the acidity or alkalinity of the soil. More precisely, it is a measure of hydronium concentration in an aqueous solution and ranges in values from 0 to 14 (acidic to basic) but practically speaking for soils, pH ranges from 3.5 to 9.5, as pH values beyond those extremes are toxic to life forms. At 25 °C an aqueous solution that has a pH of 3.5 has 10 moles H 3 O (hydronium ions) per litre of solution (and also 10 moles per litre OH ). A pH of 7, defined as neutral, has 10 moles of hydronium ions per litre of solution and also 10 moles of OH per litre; since

2328-509: Is a small, insoluble particle ranging in size from 1 nanometer to 1 micrometer , thus small enough to remain suspended by Brownian motion in a fluid medium without settling. Most soils contain organic colloidal particles called humus as well as the inorganic colloidal particles of clays . The very high specific surface area of colloids and their net electrical charges give soil its ability to hold and release ions . Negatively charged sites on colloids attract and release cations in what

2425-411: Is about 50% solids (45% mineral and 5% organic matter), and 50% voids (or pores) of which half is occupied by water and half by gas. The percent soil mineral and organic content can be treated as a constant (in the short term), while the percent soil water and gas content is considered highly variable whereby a rise in one is simultaneously balanced by a reduction in the other. The pore space allows for

2522-424: Is also a net sink of methane (CH 4 ) but a net producer of methane (a strong heat-absorbing greenhouse gas ) when soils are depleted of oxygen and subject to elevated temperatures. Soil atmosphere is also the seat of emissions of volatiles other than carbon and nitrogen oxides from various soil organisms, e.g. roots, bacteria, fungi, animals. These volatiles are used as chemical cues, making soil atmosphere

2619-403: Is an impermeable buoyant material. It is the phellem layer of bark tissue which is harvested for commercial use primarily from Quercus suber (the cork oak), which is native to southwest Europe and northwest Africa . Cork is composed of suberin , a hydrophobic substance. Because of its impermeable, buoyant, elastic, and fire retardant properties, it is used in a variety of products,

2716-556: Is an important characteristic of soil. This ventilation can be accomplished via networks of interconnected soil pores , which also absorb and hold rainwater making it readily available for uptake by plants. Since plants require a nearly continuous supply of water, but most regions receive sporadic rainfall, the water-holding capacity of soils is vital for plant survival. Soils can effectively remove impurities, kill disease agents, and degrade contaminants , this latter property being called natural attenuation . Typically, soils maintain

2813-464: Is assumed acid-forming cations). Base saturation is almost in direct proportion to pH (it increases with increasing pH). It is of use in calculating the amount of lime needed to neutralise an acid soil (lime requirement). The amount of lime needed to neutralize a soil must take account of the amount of acid forming ions on the colloids (exchangeable acidity), not just those in the soil water solution (free acidity). The addition of enough lime to neutralize

2910-414: Is called the pedosphere . The pedosphere interfaces with the lithosphere , the hydrosphere , the atmosphere , and the biosphere . Soil has four important functions : All of these functions, in their turn, modify the soil and its properties. Soil science has two basic branches of study: edaphology and pedology . Edaphology studies the influence of soils on living things. Pedology focuses on

3007-401: Is called the soil solution. Since soil water is never pure water, but contains hundreds of dissolved organic and mineral substances, it may be more accurately called the soil solution. Water is central to the dissolution , precipitation and leaching of minerals from the soil profile . Finally, water affects the type of vegetation that grows in a soil, which in turn affects the development of

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3104-421: Is dependent on the type of parent material , the processes that modify those parent materials, and the soil-forming factors that influence those processes. The biological influences on soil properties are strongest near the surface, though the geochemical influences on soil properties increase with depth. Mature soil profiles typically include three basic master horizons: A, B, and C. The solum normally includes

3201-423: Is gaining popularity as a non-allergenic, easy-to-handle and safe alternative to petrochemical-based insulation products. Cork is also used to make vinyl record slipmats, due to its ability to not attract dust. They also dampen static and vibrations. Sheets of cork, also often the by-product of stopper production, are used to make bulletin boards as well as floor and wall tiles . Cork's low density makes it

3298-401: Is induced. Capillary action is responsible for moving groundwater from wet regions of the soil to dry areas. Subirrigation designs (e.g., wicking beds , sub-irrigated planters ) rely on capillarity to supply water to plant roots. Capillary action can result in an evaporative concentration of salts, causing land degradation through salination . Soil moisture measurement —measuring

3395-531: Is likely home to 59 ± 15% of the species on Earth. Enchytraeidae (worms) have the greatest percentage of species in soil (98.6%), followed by fungi (90%), plants (85.5%), and termites ( Isoptera ) (84.2%). Many other groups of animals have substantial fractions of species living in soil, e.g. about 30% of insects , and close to 50% of arachnids . While most vertebrates live above ground (ignoring aquatic species), many species are fossorial , that is, they live in soil, such as most blind snakes . The chemistry of

3492-421: Is made up of suberin (average of about 40%), lignin (22%), polysaccharides ( cellulose and hemicellulose ) (18%), extractables (15%) and others. Cork is a natural material used by humans for over 5,000 years. It is a material whose applications have been known since antiquity , especially in floating devices and as stopper for beverages , mainly wine , whose market, from the early twentieth century, had

3589-477: Is more advanced. Most plant nutrients, with the exception of nitrogen , originate from the minerals that make up the soil parent material. Some nitrogen originates from rain as dilute nitric acid and ammonia , but most of the nitrogen is available in soils as a result of nitrogen fixation by bacteria . Once in the soil-plant system, most nutrients are recycled through living organisms, plant and microbial residues (soil organic matter), mineral-bound forms, and

3686-409: Is referred to as cation exchange . Cation-exchange capacity is the amount of exchangeable cations per unit weight of dry soil and is expressed in terms of milliequivalents of positively charged ions per 100 grams of soil (or centimoles of positive charge per kilogram of soil; cmol c /kg ). Similarly, positively charged sites on colloids can attract and release anions in the soil, giving

3783-814: Is situated 30 km from Taza National Park ; this national park and other vicinity features support a variety of flora and fauna. It is an important habitat for the endangered Barbary macaque , Macaca sylvanus . Originally Phoenician, Igilgili passed to the Carthaginians , the Roman Republic and Empire , the Vandals , the Byzantines , the Umayyads , the Genovese , and the Ottomans . It

3880-411: Is stacked in piles in the forest or in yards at a factory and traditionally left to dry, after which it can be loaded onto a truck and shipped to a processor. Bark from initial harvests can be used to make flooring, shoes, insulation and other industrial products. Subsequent extractions usually occur at intervals of nine years, though it can take up to thirteen for the cork to reach an acceptable size. If

3977-545: Is very little organic material. Basaltic minerals commonly weather relatively quickly, according to the Goldich dissolution series . The plants are supported by the porous rock as it is filled with nutrient-bearing water that carries minerals dissolved from the rocks. Crevasses and pockets, local topography of the rocks, would hold fine materials and harbour plant roots. The developing plant roots are associated with mineral-weathering mycorrhizal fungi that assist in breaking up

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4074-490: The aeration of the soil and the ability of water to infiltrate and to be held within the soil. Soil water content can be measured as volume or weight . Soil moisture levels, in order of decreasing water content, are saturation, field capacity , wilting point , air dry, and oven dry. Field capacity describes a drained wet soil at the point water content reaches equilibrium with gravity. Irrigating soil above field capacity risks percolation losses. Wilting point describes

4171-561: The humus form ), the copedon (in intermediary position, where most weathering of minerals takes place) and the lithopedon (in contact with the subsoil). The soil texture is determined by the relative proportions of the individual particles of sand , silt , and clay that make up the soil. The interaction of the individual mineral particles with organic matter, water, gases via biotic and abiotic processes causes those particles to flocculate (stick together) to form aggregates or peds . Where these aggregates can be identified,

4268-425: The mineralogy of those particles can strongly modify those properties. The mineralogy of the finest soil particles, clay, is especially important. Large numbers of microbes , animals , plants and fungi are living in soil. However, biodiversity in soil is much harder to study as most of this life is invisible, hence estimates about soil biodiversity have been unsatisfactory. A recent study suggested that soil

4365-448: The A and B horizons. The living component of the soil is largely confined to the solum, and is generally more prominent in the A horizon. It has been suggested that the pedon , a column of soil extending vertically from the surface to the underlying parent material and large enough to show the characteristics of all its horizons, could be subdivided in the humipedon (the living part, where most soil organisms are dwelling, corresponding to

4462-601: The Cork Supply Group of Portugal concluded that cork is the most environmentally friendly wine stopper in comparison to other alternatives. The Corticeira Amorim 's study, in particular ("Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures"), was developed by PricewaterhouseCoopers , according to ISO 14040 . Results concluded that, concerning the emission of greenhouse gases, each plastic stopper released 10 times more CO 2 , whilst an aluminium screw cap releases 26 times more CO 2 than does

4559-668: The Stelvin as it is a guarantee that the wine will be good even after many decades of ageing. Some consumers may have conceptions about screw caps being representative of lower quality wines, due to their cheaper price; however, in Australia, for example, much of the non-sparkling wine production now uses these Stelvin caps as a cork alternative, although some have recently switched back to cork citing issues using screw caps. The alternatives to cork have both advantages and disadvantages. For example, screwtops are generally considered to offer

4656-406: The acronym CROPT. The physical properties of soils, in order of decreasing importance for ecosystem services such as crop production , are texture , structure , bulk density , porosity , consistency, temperature , colour and resistivity . Soil texture is determined by the relative proportion of the three kinds of soil mineral particles, called soil separates: sand , silt , and clay . At

4753-446: The addition of any more hydronium ions or aluminum hydroxyl cations drives the pH even lower (more acidic) as the soil has been left with no buffering capacity. In areas of extreme rainfall and high temperatures, the clay and humus may be washed out, further reducing the buffering capacity of the soil. In low rainfall areas, unleached calcium pushes pH to 8.5 and with the addition of exchangeable sodium, soils may reach pH 10. Beyond

4850-452: The apparent sterility of tropical soils. Live plant roots also have some CEC, linked to their specific surface area. Anion exchange capacity is the soil's ability to remove anions (such as nitrate , phosphate ) from the soil water solution and sequester those for later exchange as the plant roots release carbonate anions to the soil water solution. Those colloids which have low CEC tend to have some AEC. Amorphous and sesquioxide clays have

4947-437: The atmosphere due to increased biological activity at higher temperatures, a positive feedback (amplification). This prediction has, however, been questioned on consideration of more recent knowledge on soil carbon turnover. Soil acts as an engineering medium, a habitat for soil organisms , a recycling system for nutrients and organic wastes , a regulator of water quality , a modifier of atmospheric composition , and

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5044-527: The bark is stripped to harvest the cork. The tree continues to live and grow. The sustainability of production and the easy recycling of cork products and by-products are two of its most distinctive aspects. Cork oak forests also prevent desertification and are a particular habitat in the Iberian Peninsula and the refuge of various endangered species . Carbon footprint studies conducted by Corticeira Amorim , Oeneo Bouchage of France and

5141-536: The bark make the cork itself highly inconsistent. In a 2005 closure study, 45% of corks showed gas leakage during pressure testing both from the sides of the cork as well as through the cork body itself. Since the mid-1990s, a number of wine brands have switched to alternative wine closures such as plastic stoppers, screw caps , or other closures. During 1972 more than half of the Australian bottled wine went bad due to corking. A great deal of anger and suspicion

5238-426: The basic cations are forced off the soil colloids by the mass action of hydronium ions from usual or unusual rain acidity against those attached to the colloids. High rainfall rates can then wash the nutrients out, leaving the soil inhabited only by those organisms which are particularly efficient to uptake nutrients in very acid conditions, like in tropical rainforests . Once the colloids are saturated with H 3 O ,

5335-426: The coast and there is a citadel to the north. There is a hospital, previously a Catholic church (which was demolished), mosques and University of Jijel . A relatively new port has been built at Djen Djen , approximately 7 miles east of Jijel, which can handle large bulk carriers having a draft up to 18.2m. Presently, the port is mainly used by car carriers and break bulk vessels. Cork (material) Cork

5432-416: The cork are known as extractors . An extractor uses a very sharp axe to make two types of cuts on the tree: one horizontal cut around the plant, called a crown or necklace , at a height of about two to three times the circumference of the tree, and several vertical cuts called rulers or openings . This is the most delicate phase of the work because, even though cutting the cork requires significant force,

5529-552: The cork oak, they have corky bark but not thick enough for cork production. Cork is extracted only from early May to late August, when the cork can be separated from the tree without causing permanent damage. When the tree reaches 25–30 years of age and about 24 in (60 cm) in circumference, the cork can be removed for the first time. However, this first harvest almost always produces poor quality or virgin cork (Portuguese cortiça virgem ; Spanish corcho bornizo or corcho virgen ). The workers who specialize in removing

5626-436: The dry limit for growing plants. During growing season, soil moisture is unaffected by functional groups or specie richness. Available water capacity is the amount of water held in a soil profile available to plants. As water content drops, plants have to work against increasing forces of adhesion and sorptivity to withdraw water. Irrigation scheduling avoids moisture stress by replenishing depleted water before stress

5723-475: The extractor must not damage the underlying phellogen or the tree will be harmed. To free the cork from the tree, the extractor pushes the handle of the axe into the rulers. A good extractor needs to use a firm but precise touch in order to free a large amount of cork without damaging the product or tree. These freed portions of the cork are called planks . The planks are usually carried off by hand since cork forests are rarely accessible to vehicles. The cork

5820-527: The formation, description (morphology), and classification of soils in their natural environment. In engineering terms, soil is included in the broader concept of regolith , which also includes other loose material that lies above the bedrock, as can be found on the Moon and other celestial objects . Soil is a major component of the Earth 's ecosystem . The world's ecosystems are impacted in far-reaching ways by

5917-419: The highest AEC, followed by the iron oxides. Levels of AEC are much lower than for CEC, because of the generally higher rate of positively (versus negatively) charged surfaces on soil colloids, to the exception of variable-charge soils. Phosphates tend to be held at anion exchange sites. Iron and aluminum hydroxide clays are able to exchange their hydroxide anions (OH ) for other anions. The order reflecting

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6014-632: The infiltration and movement of air and water, both of which are critical for life existing in soil. Compaction , a common problem with soils, reduces this space, preventing air and water from reaching plant roots and soil organisms. Given sufficient time, an undifferentiated soil will evolve a soil profile that consists of two or more layers, referred to as soil horizons. These differ in one or more properties such as in their texture , structure , density , porosity, consistency, temperature, color, and reactivity . The horizons differ greatly in thickness and generally lack sharp boundaries; their development

6111-479: The intent to age. Stoppers which resemble natural cork very closely can be made by isolating the suberin component of the cork from the undesirable lignin , mixing it with the same substance used for contact lenses and an adhesive, and molding it into a standardized product, free of TCA or other undesirable substances. Composite corks with real cork veneers are used in cheaper wines. Celebrated Australian wine writer and critic James Halliday has written that since

6208-418: The mid-17th century, French vintners did not use cork stoppers, using instead oil-soaked rags stuffed into the necks of bottles. Wine corks can be made of either a single piece of cork, or composed of particles, as in champagne corks; corks made of granular particles are called "agglomerated corks". Natural cork closures are used for about 80% of the 20 billion bottles of wine produced each year. After

6305-539: The most common of which is wine stoppers . The montado landscape of Portugal produces approximately half of the cork harvested annually worldwide, with Corticeira Amorim being the leading company in the industry. Cork was examined microscopically by Robert Hooke , which led to his discovery and naming of the cell . Cork composition varies depending on geographic origin, climate and soil conditions, genetic origin, tree dimensions, age (virgin or reproduction), and growth conditions. However, in general, cork

6402-429: The negatively charged colloids resist being washed downward by water and are out of reach of plant roots, thereby preserving the soil fertility in areas of moderate rainfall and low temperatures. There is a hierarchy in the process of cation exchange on colloids, as cations differ in the strength of adsorption by the colloid and hence their ability to replace one another ( ion exchange ). If present in equal amounts in

6499-412: The negatively-charged soil colloid exchange sites (CEC) that are occupied by base-forming cations is called base saturation . If a soil has a CEC of 20 meq and 5 meq are aluminium and hydronium cations (acid-forming), the remainder of positions on the colloids ( 20 − 5 = 15 meq ) are assumed occupied by base-forming cations, so that the base saturation is 15 ÷ 20 × 100% = 75% (the compliment 25%

6596-419: The next larger scale, soil structures called peds or more commonly soil aggregates are created from the soil separates when iron oxides , carbonates , clay, silica and humus , coat particles and cause them to adhere into larger, relatively stable secondary structures. Soil bulk density , when determined at standardized moisture conditions, is an estimate of soil compaction . Soil porosity consists of

6693-472: The ocean has no more than 10 prokaryotic organisms per milliliter (gram) of seawater. Organic carbon held in soil is eventually returned to the atmosphere through the process of respiration carried out by heterotrophic organisms, but a substantial part is retained in the soil in the form of soil organic matter; tillage usually increases the rate of soil respiration , leading to the depletion of soil organic matter. Since plant roots need oxygen, aeration

6790-635: The other cations more weakly bound to colloids are pushed into solution as hydrogen ions occupy exchange sites ( protonation ). A low pH may cause the hydrogen of hydroxyl groups to be pulled into solution, leaving charged sites on the colloid available to be occupied by other cations. This ionisation of hydroxy groups on the surface of soil colloids creates what is described as pH-dependent surface charges. Unlike permanent charges developed by isomorphous substitution , pH-dependent charges are variable and increase with increasing pH. Freed cations can be made available to plants but are also prone to be leached from

6887-492: The plant roots release hydrogen ions to the solution. CEC is the amount of exchangeable hydrogen cation (H ) that will combine with 100 grams dry weight of soil and whose measure is one milliequivalents per 100 grams of soil (1 meq/100 g). Hydrogen ions have a single charge and one-thousandth of a gram of hydrogen ions per 100 grams dry soil gives a measure of one milliequivalent of hydrogen ion. Calcium, with an atomic weight 40 times that of hydrogen and with

6984-486: The porous lava, and by these means organic matter and a finer mineral soil accumulate with time. Such initial stages of soil development have been described on volcanoes, inselbergs, and glacial moraines. How soil formation proceeds is influenced by at least five classic factors that are intertwined in the evolution of a soil: parent material, climate, topography (relief), organisms, and time. When reordered to climate, relief, organisms, parent material, and time, they form

7081-414: The processes carried out in the soil, with effects ranging from ozone depletion and global warming to rainforest destruction and water pollution . With respect to Earth's carbon cycle , soil acts as an important carbon reservoir , and it is potentially one of the most reactive to human disturbance and climate change . As the planet warms, it has been predicted that soils will add carbon dioxide to

7178-565: The product is of high quality it is known as gentle cork (Portuguese cortiça amadia , but also cortiça secundeira only if it is the second time; Spanish corcho segundero , also restricted to the second time ), and, ideally, is used to make stoppers for wine and champagne bottles. Cork's elasticity combined with its near-impermeability makes it suitable as a material for bottle stoppers , especially for wine bottles . Cork stoppers represent about 60% of all cork based production. Cork has an almost zero Poisson's ratio , which means

7275-497: The radius of a cork does not change significantly when squeezed or pulled. Cork is an excellent gasket material. Some carburetor float bowl gaskets are made of cork, for example. Cork is also an essential element in the production of badminton shuttlecocks . Cork's bubble-form structure and natural fire retardant make it suitable for acoustic and thermal insulation in house walls, floors, ceilings, and facades. The by-product of more lucrative stopper production, corkboard,

7372-414: The rate of diffusion of gases into and out of soil. Platy soil structure and soil compaction (low porosity) impede gas flow, and a deficiency of oxygen may encourage anaerobic bacteria to reduce (strip oxygen) from nitrate NO 3 to the gases N 2 , N 2 O, and NO, which are then lost to the atmosphere, thereby depleting the soil of nitrogen, a detrimental process called denitrification . Aerated soil

7469-442: The seat of interaction networks playing a decisive role in the stability, dynamics and evolution of soil ecosystems. Biogenic soil volatile organic compounds are exchanged with the aboveground atmosphere, in which they are just 1–2 orders of magnitude lower than those from aboveground vegetation. Humans can get some idea of the soil atmosphere through the well-known 'after-the-rain' scent, when infiltering rainwater flushes out

7566-441: The soil anion exchange capacity. The cation exchange, that takes place between colloids and soil water, buffers (moderates) soil pH, alters soil structure, and purifies percolating water by adsorbing cations of all types, both useful and harmful. The negative or positive charges on colloid particles make them able to hold cations or anions, respectively, to their surfaces. The charges result from four sources. Cations held to

7663-538: The soil by volatilisation (loss to the atmosphere as gases) or leaching. Soil is said to be formed when organic matter has accumulated and colloids are washed downward, leaving deposits of clay, humus , iron oxide , carbonate , and gypsum , producing a distinct layer called the B horizon. This is a somewhat arbitrary definition as mixtures of sand, silt, clay and humus will support biological and agricultural activity before that time. These constituents are moved from one level to another by water and animal activity. As

7760-420: The soil solution composition (attenuate changes in the soil solution) as soils wet up or dry out, as plants take up nutrients, as salts are leached, or as acids or alkalis are added. Plant nutrient availability is affected by soil pH , which is a measure of the hydrogen ion activity in the soil solution. Soil pH is a function of many soil forming factors, and is generally lower (more acidic) where weathering

7857-402: The soil solution. Both living soil organisms (microbes, animals and plant roots) and soil organic matter are of critical importance to this recycling, and thereby to soil formation and soil fertility . Microbial soil enzymes may release nutrients from minerals or organic matter for use by plants and other microorganisms, sequester (incorporate) them into living cells, or cause their loss from

7954-473: The soil voids are saturated with water vapour, at least until the point of maximal hygroscopicity , beyond which a vapour-pressure deficit occurs in the soil pore space. Adequate porosity is necessary, not just to allow the penetration of water, but also to allow gases to diffuse in and out. Movement of gases is by diffusion from high concentrations to lower, the diffusion coefficient decreasing with soil compaction . Oxygen from above atmosphere diffuses in

8051-430: The soil water solution will be insufficient to change the pH, as the acid forming cations stored on the soil colloids will tend to restore the original pH condition as they are pushed off those colloids by the calcium of the added lime. The resistance of soil to change in pH, as a result of the addition of acid or basic material, is a measure of the buffering capacity of a soil and (for a particular soil type) increases as

8148-433: The soil water solution: Al replaces H replaces Ca replaces Mg replaces K same as NH 4 replaces Na If one cation is added in large amounts, it may replace the others by the sheer force of its numbers. This is called law of mass action . This is largely what occurs with the addition of cationic fertilisers ( potash , lime ). As the soil solution becomes more acidic (low pH , meaning an abundance of H ),

8245-462: The soil where it is consumed and levels of carbon dioxide in excess of above atmosphere diffuse out with other gases (including greenhouse gases ) as well as water. Soil texture and structure strongly affect soil porosity and gas diffusion. It is the total pore space ( porosity ) of soil, not the pore size, and the degree of pore interconnection (or conversely pore sealing), together with water content, air turbulence and temperature, that determine

8342-502: The soil, a complex feedback which is exemplified in the dynamics of banded vegetation patterns in semi-arid regions. Soils supply plants with nutrients , most of which are held in place by particles of clay and organic matter ( colloids ) The nutrients may be adsorbed on clay mineral surfaces, bound within clay minerals ( absorbed ), or bound within organic compounds as part of the living organisms or dead soil organic matter. These bound nutrients interact with soil water to buffer

8439-414: The soil, possibly making the soil less fertile. Plants are able to excrete H into the soil through the synthesis of organic acids and by that means, change the pH of the soil near the root and push cations off the colloids, thus making those available to the plant. Cation exchange capacity is the soil's ability to remove cations from the soil water solution and sequester those to be exchanged later as

8536-409: The strength of anion adhesion is as follows: The amount of exchangeable anions is of a magnitude of tenths to a few milliequivalents per 100 g dry soil. As pH rises, there are relatively more hydroxyls, which will displace anions from the colloids and force them into solution and out of storage; hence AEC decreases with increasing pH (alkalinity). Soil reactivity is expressed in terms of pH and

8633-421: The trees are about 25 years old the cork is traditionally stripped from the trunks every nine years, with the first two harvests generally producing lower quality cork ( male cork or virgin cork ). The trees live for about 300 years. The cork industry is generally regarded as environmentally friendly. Cork production is generally considered sustainable because the cork tree is not cut down to obtain cork; only

8730-491: The two concentrations are equal, they are said to neutralise each other. A pH of 9.5 has 10 moles hydronium ions per litre of solution (and also 10 moles per litre OH ). A pH of 3.5 has one million times more hydronium ions per litre than a solution with pH of 9.5 ( 9.5 − 3.5 = 6 or 10 ) and is more acidic. The effect of pH on a soil is to remove from the soil or to make available certain ions. Soils with high acidity tend to have toxic amounts of aluminium and manganese . As

8827-473: The void part of the soil volume and is occupied by gases or water. Soil consistency is the ability of soil materials to stick together. Soil temperature and colour are self-defining. Resistivity refers to the resistance to conduction of electric currents and affects the rate of corrosion of metal and concrete structures which are buried in soil. These properties vary through the depth of a soil profile, i.e. through soil horizons . Most of these properties determine

8924-553: The water content of the soil, as can be expressed in terms of volume or weight—can be based on in situ probes (e.g., capacitance probes , neutron probes ), or remote sensing methods. Soil moisture measurement is an important factor in determining changes in soil activity. The atmosphere of soil, or soil gas , is very different from the atmosphere above. The consumption of oxygen by microbes and plant roots, and their release of carbon dioxide, decreases oxygen and increases carbon dioxide concentration. Atmospheric CO 2 concentration

9021-461: The weathering of lava flow bedrock, which would produce the purely mineral-based parent material from which the soil texture forms. Soil development would proceed most rapidly from bare rock of recent flows in a warm climate, under heavy and frequent rainfall. Under such conditions, plants (in a first stage nitrogen-fixing lichens and cyanobacteria then epilithic higher plants ) become established very quickly on basaltic lava, even though there

9118-476: The whole soil atmosphere after a drought period, or when soil is excavated, a bulk property attributed in a reductionist manner to particular biochemical compounds such as petrichor or geosmin . Soil particles can be classified by their chemical composition ( mineralogy ) as well as their size. The particle size distribution of a soil, its texture, determines many of the properties of that soil, in particular hydraulic conductivity and water potential , but

9215-711: Was conquered for the last time in the 16th century by Hayreddin Barbarossa . In July 1664, the French took the city . Resistance was organised under the direction of Shaban Aga and the French were driven out in October of the same year. Jijel remained a corsair stronghold until recaptured by the French in 1839. Strong local resistance, finally subdued in 1851, resulted in the construction of three forts along its southern fringe as well as minimal colonisation. The original town

9312-487: Was devastated by an earthquake in 1856. Due to the rugged landscape, Jijel is slightly isolated. However, it is connected by road to large cities like Bejaïa (90 km west), Setif (135 km southwest) and Constantine (150 km southeast). The city also has its own airport Jijel Ferhat Abbas Airport . Jijel is built along modern patterns with wide streets framed by trees. The surroundings consist largely of dense cork-oak forest. A peninsula lies right out from

9409-422: Was directed at Portuguese and Spanish cork suppliers who were suspected of deliberately supplying bad cork to non- EEC wine makers to help prevent cheap imports. Cheaper wine makers developed the aluminium "Stelvin" cap with a polypropylene stopper wad. More expensive wines and carbonated varieties continued to use cork, although much closer attention was paid to the quality. Even so, some high premium makers prefer

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