Kamis, 28 Oktober 2010

Sensory garden

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A sensory garden in Bremen
A sensory garden is a garden or other plot specifically created to be accessible and enjoyable to visitors, both disabled and non-disabled. The purpose of such a provision is to provide individual and combined sensory opportunities for the user such that they may not normally experience.
A sensory garden, for example, may contain features accessible to the disabled individual such as: scented and edible plants, sculptures and sculpted handrails, water features designed to make sound and play over the hands, textured touch-pads, magnifying-glass screens, braille and audio induction loop descriptions. Depending on the user group, other provisions may integrate sound and music more centrally to combine the play needs of younger users with their sensory needs.
Many sensory gardens devote themselves to providing experience for multiple senses; those specialising in scent are sometimes called scented gardens, those specialising in music/sound are sound gardens where the equipment doubles up to provides an enhanced opportunity for strategic developmental, learning and educational outcomes.
Sensory Gardens usually have an enhanced infrastructure to permit wheelchair access and meet other accessibility concerns; the design and layout provides a stimulating journey through the senses, heightening awareness, and bringing positive learning experiences

Welcome to a Sensory Garden

Posted in Sensory Garden on May 14th, 2010 by admin — Comments Off
At Sensory Garden is a garden or other plot especially created to be accessible not to mention enjoyable to visitors, both disabled and non-disabled. The objective of such a sensory garden space is always to deliver individual and even mixed sensory journeys for those people who may not ever get to commonly encounter.
A sensory garden, for example, might contain features accessible for the disabled individual along the lines of: fragrant and edible plants, sculptures together with sculpted handrails, water features designed to create sound and play over the hands, distinctive touch-pads, magnifying-glass displays, braille and sound induction loop verbal descriptions. Depending on the persons in the group, other provisions may integrate sound and songs more centrally to incorporate the play requirements associated with children and younger users using their senses .
Quite a few sensory gardens devote themselves to providing experience to numerous senses; those specialising in scent are often called scented gardens, those specialising in sound and music are called sound gardens where the technology increases to provide an increased chance of strategic developmental, enlightening the visitor with informative benefits.
Sensory Gardens typically have an enhanced facilities to allow wheelchairs to get round and meet various other accessibility concerns; the design is set up so that it delivers a revitalizing experience via the senses, heightening consciousness and bringing together a whole range of beneficial learning experiences.

Welcome to a Sensory Garden

At Sensory Garden is a garden or other plot especially created to be accessible not to mention enjoyable to visitors, both disabled and non-disabled. The objective of such a sensory garden space is always to deliver individual and even mixed sensory journeys for those people who may not ever get to commonly encounter.
A sensory garden, [...]

Sculpture garden

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The Esplanade Ernest-Cormier, a sculpture garden in Montreal, with Melvin Charney's work Colonnes allégoriques. This sculpture garden consists of both an ensemble of free-standing sculptures and a large installation building "shell," mirroring the Canadian Centre for Architecture across the street, and through which visitors can move.
The Tehran Museum of Contemporary Art has a sculpture Garden adjacent to Tehran's Laleh Park.
A sculpture garden is an outdoor garden dedicated to the presentation of sculpture, usually several permanently-sited works in durable materials in landscaped surroundings.
A sculpture garden may be private, owned by a museum and accessible freely or for a fee, or public and accessible to all. Some cities own large numbers of public sculptures, some of which they may present together in city parks.
Exhibits range from individual, traditional sculptures to large site-specific installations.

Raised bed gardening

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Raised bed gardening
Raised bed gardening is a form of gardening in which the soil is formed in 3–4 foot (1.0–1.2 m) wide beds, which can be of any length or shape. The soil is raised above the surrounding soil (6 inches to waist high), sometimes enclosed by a frame generally made of wood, rock, or concrete blocks, and enriched with compost. The vegetable plants are spaced in geometric patterns, much closer together than conventional row gardening. The spacing is such that when the vegetables are fully grown, their leaves just barely touch each other, creating a microclimate in which moisture is conserved and weed growth suppressed. Raised beds produce a variety of benefits: they extend the planting season; they reduce the need to use poor native soil; and they can reduce weeds if designed properly. Since the gardener does not walk on the raised beds, the soil is not compacted and the roots have an easier time growing. The close plant spacing and the use of compost generally result in higher yields with raised beds in comparison to conventional row gardening. Waist high raised beds enable the elderly and the sick to grow vegetables without having to bend over to tend them.
Raised beds lend themselves to the development of complex agriculture systems that utilize many of the principles and methods of Permaculture. They can be used effectively to control erosion and recycle and conserve water and nutrients by building them along contour lines on slopes. This also makes more space available for intensive crop production. They can be created over large areas with the use of several commonly available tractor-drawn implements and efficiently maintained, planted and harvested using hand tools.
This form of gardening is compatible with square foot gardening and companion planting.
Circular waist high raised beds with a path to the center (a slice of the circle cut out) are called keyhole gardens. Often the center has a chimney of sorts built with sticks and then lined with feedbags or grasses that allows water placed at the center to flow out into the soil and reach the plants' roots. The charity 'Send a Cow' is promoting the creation of these in Africa.
Vegetable Garden Bed Construction materials should be chosen carefully. Some concerns exist over the use of timber such as Treated Pine that was traditionally treated using Chromated Copper Arsenateor CCA, a toxic chemical mix for preserving timber that may leach chemicals into the soil which in turn can be drawn up into the plants, a concern for vegetable growers, where part or all of the plant is eaten. If using timber to raise the garden bed, ensure that it is an untreated hardwood to prevent the risk of chemicals leaching into the soil. A common approach is to use timber sleepers joined with steel rods to hold them together. Another approach is to use concrete blocks, although less aesthetically pleasing, they are cheap to source and easy to use. On the market are also prefab raised garden bed solutions which are made from long lasting polyethylene that is UV stabilized and Food Grade so it isn't going to leach undesirable chemicals into your soil and it won't deteriorate in the elements. A double skinned wall provides an air pocket of insulation that minimizes the temperature fluctuations and drying out of the soil in the garden bed.

Waru Warn

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  (Redirected from Waru Waru)
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Waru Warn or Waru Waru is an agricultural technique developed by the Quechuas in South America before the rise of the Inca Empire. It is dated around 300 B.C.[1]
The technique has been revived in 1984, in Tiawanaco, Bolivia, and Puno, Peru.
The technique consists in combining raised beds with irrigation channels so as to prevent damage due to soil erosion during floods. The technique ensures both collecting of water (either fluvial water, rainwater or phreatic water) and subsequent drainage. The drainage aspect makes it particularly interesting for areas subject to risks of brutal floods, such as tropical parts of Bolivia and Peru where it emerged.

Therapeutic garden

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A Therapeutic Garden is an outdoor garden space that has been specifically designed to meet the physical, psychological, social and spiritual needs of the people using the garden as well as their caregivers, family members and friends.
Therapeutic Gardens can be found in a variety of settings, including but not limited to hospitals, skilled nursing homes, assisted living residences, continuing care retirement communities, out-patient cancer centers, hospice residences, and other related healthcare and residential environments. The focus of the gardens is primarily on incorporating plants and friendly wildlife into the space. The settings can be designed to include active uses such as raised planters for horticultural therapy activities or programmed for passive uses such as quiet private sitting areas next to a small pond with a trickling waterfall.

Design

The design of a Therapeutic Garden is ideally a collaborative effort involving the people using and caring for the garden. The development of the garden is typically accomplished by a design team of healthcare professionals, such as doctors, nurses, occupational therapists, recreational therapists, gerontologists and other staff members. Additional stakeholders involved may include, if appropriate, the patients or residents themselves and their respective family members and other caregivers. The design team is often led by a landscape architect or other design professional trained in the design and development of Therapeutic Gardens. Depending upon the actual use of the garden, other members of the design team may include a horticultural therapist, recreational therapist and related disciplines.
The majority of elements in a Therapeutic Garden should be plant related, such as perennials that attract hummingbirds, shrubs that attract butterflies and water features for gold fish and Koi. Plants familiar to those using the Therapeutic Garden need to be non-toxic and non-injurious. Issues related to sustainability of the garden, such as using native plants and rain water harvesting, should also be considered in the overall design. Attracting nature, such as butterflies, gold finch and hummingbirds into the Therapeutic Garden, is important. Nature is referred to as a ‘positive distraction’ by Roger Ulrich, Ph.D. at Texas A&M University[1]. Other considerations include providing ample shade, movable furniture, water features, smooth and level walking surfaces, and year round interest. Consideration should also be given to the maintenance and upkeep of the Therapeutic Garden as safety is an important consideration. An endowment fund can be set up for the perpetual maintenance of the Therapeutic Garden.

Elements

The elements of a Therapeutic Garden consist of the following:
Natural elements:
Constructed garden elements:
  • Patio, courtyard
  • Paved walking pathways
  • Seating, such as tables, chairs and benches
  • Landscape lighting
  • Raised beds
  • Shade, such as Gazebos , Pergolas or umbrellas with tables
  • Fountain, water garden, or other water features
  • Hose bib or other water source
  • Electrical outdoor outlet; for music and related activities
  • Nature

    Spending time outside in a garden has been shown to positively affect a person’s emotions and improve their sense of well-being. Access to nature balances circadian rhythms, lowers blood pressure, reduces stress and increases absorption of Vitamin D. Nature has been shown to be beneficial for our overall health and well-being. We are all connected to nature and it is important to maintain this vital connection for our health and well-being, which is described in the work ‘The Biophilia Hypothesis’ by Edward O. Wilson[2].

    Garden Programs

    Healing gardens for hospitals have put a new emphasis on creating garden programs where patients can go. This model takes the form of the Swedish Covenant Hospital system [3]. Landscape artist David Kemp has a business on the East Coast of the United States designing healing gardens for hospitals. [4]

    Therapeutic Gardens in literature

  • Healing Gardens: Therapeutic Benefits and Design Recommendations
  • Healing Landscapes: Therapeutic Outdoor Environments
  • The Healing Landscape: Gardening for the Mind, Body, and Soul
  • Restorative Gardens: The Healing Landscape
  • Interaction by Design: Bringing People and Plants Together for Health and Well-Being
  • Design for Aging: Post-Occupancy Evaluations
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Knot garden

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Knot gardens were first established in the UK in the reign of Queen Elizabeth I.
Knot Garden at St Fagans museum of country life, south Wales
A knot garden is a very formal design of garden in a square frame and grown with a variety or aromatic plants and culinary herbs including Germander, marjoram, thyme, southernwood, lemon balm, hyssop, costmary, acanthus, mallow, chamomile, rosemary, Calendulas, Violas and Santolina. Most knot gardens now have edges made from Box (Buxus sempervirens) of which the leaves have a sweet smell when bruised. The paths in between are usually laid with fine gravel. However, the original designs of knot gardens did not have the low box hedges, and knot gardens with such hedges might more accurately be called Parterres
Some early knot gardens have been covered over by lawn or other landscaping, but the original traces are still visible as undulations in the present day landscape. An example of this phenomenon is the early 17th century garden of Muchalls Castle in Scotland.
Most Renaissance knot gardens were composed of square compartments. A small garden might consist of one compartment, while large gardens might contain six or eight compartments.

Examples of Knot Gardens

The Knot Garden at the Red Lodge Museum, Bristol.
Knot Gardens have become established in many temperate formal gardens throughout the world including:
  • Antony House, Cornwall, UK
  • St Fagans, South Wales
  • Alexandra Hicks Herb Knot Garden, University of Michigan, USA
  • Knowle, Solihull, UK
  • Brooklyn Botanic Garden, USA
  • Anzac Square, Dunedin, New Zealand
  • Red Lodge Museum, Bristol, UK
  • Western Reserve Herb Society, Cleveland Botanical Garden, Cleveland, USA
  • Hatfield House, Hertfordshire, UK
  • Kitchen garden

    From Wikipedia, the free encyclopedia
      (Redirected from Herb garden)
    Jump to: navigation, search
    Large-scale potager at Villandry, France
    The traditional kitchen garden, also known as a potager, (in French, jardin potager) is a space separate from the rest of the residential garden - the ornamental plants and lawn areas. Most vegetable gardens are still miniature versions of old family farm plots, but the kitchen garden is different not only in its history, but also its design.
    The kitchen garden may serve as the central feature of an ornamental, all-season landscape, or it may be little more than a humble vegetable plot. It is a source of herbs, vegetables, fruits, and edible flowers, but it is often also a structured garden space with a design based on repetitive geometric patterns.
    The kitchen garden has year-round visual appeal and can incorporate permanent perennials or woody shrub plantings around (or among) the annuals.

    Potager garden

    A potager is a French term for an ornamental vegetable or kitchen garden. The historical design precedent is from the Gardens of the French Renaissance and Baroque Garden à la française eras. Often flowers (edible and non-edible) and herbs are planted with the vegetables to enhance the garden's beauty. The goal is to make the function of providing food aesthetically pleasing.
    Plants are chosen as much for their functionality as for their color and form. Many are trained to grow upward. A well-designed potager can provide food, cut flowers and herbs for the home with very little maintenance. Potagers can disguise their function of providing for a home in a wide array of forms—from the carefree style of the cottage garden to the formality of a knot garden.

    Vegetable garden

    A small vegetable garden in May outside of Austin, Texas
    A vegetable garden (also known as a vegetable patch or vegetable plot) is a garden that exists to grow vegetables and other plants useful for human consumption, in contrast to a flower garden that exists for aesthetic purposes. It is a small-scale form of vegetable growing. A vegetable garden typically includes a compost heap, and several plots or divided areas of land, intended to grow one or two types of plant in each plot. It is usually located to the rear of a property in the back garden or back yard. Many families have home kitchen and vegetable gardens that they use to produce food. In World War II, many people had a garden called a 'victory garden' which provided food to families and thus freed up resources for the war effort.
    With worsening economic conditions and increased interest in organic and sustainable living, many people are turning to vegetable gardening as a supplement to their family's diet. Food grown in the back yard consumes little if any fuel for shipping or maintenance, and the grower can be sure of what exactly was used to grow it. Organic horticulture, or organic gardening, has become increasingly popular for the modern home gardener.
    There are many types of vegetable gardens. The potager, a garden in which vegetables, herbs and flowers are grown together, has become more popular than the more traditional rows or blocks.

    Herb garden

    An herbal garden at Beernem, Belgium
    The herb garden is often a separate space in the garden, devoted to growing a specific group of plants known as herbs. These gardens may be informal patches of plants, or they may be carefully designed, even to the point of arranging and clipping the plants to form specific patterns, as in a knot garden.
    Herb gardens may be purely functional, or they may include a blend of functional and ornamental plants. The herbs are usually used to flavour food in cooking, though they may also be used in other ways, such as discouraging pests, providing pleasant scents, or serving medicinal purposes (e.g., a physic garden), among others.
    A kitchen garden can be created by planting different herbs in pots or containers, with the added benefit of mobility. Although not all herbs thrive in pots or containers, some herbs do better than others. Mint, is an example of herb that is advisable to keep in a container or it will take over the whole garden [1].
    The culinary use of herbs may result in positive medical side-effects. In addition, plants grown within the garden are sometimes specifically targeted to cure common illnesses or maladies such as colds, headaches, or anxiety. During the medieval period, monks and nuns developed specialist medical knowledge and grew the necessary herbs in specialist gardens. Now, especially due to the increase in popularity of alternative medicine, this usage is heavily increasing. Making a medicinal garden however, requires a great number of plants, one for each malady.
    Herbs grown in herb gardens are also sometimes used to make herbal teas [2].
    Borage is commonly grown in herb gardens; its flowers can be used as a garnish
    Some popular culinary herbs in temperate climates are to a large extent still the same as in the medieval period.
    Examples of herbs used for specific purposes (lists are examples only, and not intended to be complete):
  • Annual culinary herbs: basil, dill, summer savory
  • Perennial culinary herbs: mint, rosemary, thyme, tarragon
  • Herbs used for potpourri: lavender, lemon verbena
  • Herbs used for tea: mint, lemon verbena, cannabis, chamomile, bergamot, Hibiscus sabdariffa (for making karkade).
  • Herbs used for other purposes: stevia for sweetening, feverfew for pest control in the garden.
However, herbs often have multiple purposes. For example, mint may be used for cooking, tea, and pest control.



  •  

Raised bed gardening

From Wikipedia, the free encyclopedia
  (Redirected from Garden bed)
Jump to: navigation, search
Raised bed gardening
Raised bed gardening is a form of gardening in which the soil is formed in 3–4 foot (1.0–1.2 m) wide beds, which can be of any length or shape. The soil is raised above the surrounding soil (6 inches to waist high), sometimes enclosed by a frame generally made of wood, rock, or concrete blocks, and enriched with compost. The vegetable plants are spaced in geometric patterns, much closer together than conventional row gardening. The spacing is such that when the vegetables are fully grown, their leaves just barely touch each other, creating a microclimate in which moisture is conserved and weed growth suppressed. Raised beds produce a variety of benefits: they extend the planting season; they reduce the need to use poor native soil; and they can reduce weeds if designed properly. Since the gardener does not walk on the raised beds, the soil is not compacted and the roots have an easier time growing. The close plant spacing and the use of compost generally result in higher yields with raised beds in comparison to conventional row gardening. Waist high raised beds enable the elderly and the sick to grow vegetables without having to bend over to tend them.
Raised beds lend themselves to the development of complex agriculture systems that utilize many of the principles and methods of Permaculture. They can be used effectively to control erosion and recycle and conserve water and nutrients by building them along contour lines on slopes. This also makes more space available for intensive crop production. They can be created over large areas with the use of several commonly available tractor-drawn implements and efficiently maintained, planted and harvested using hand tools.
This form of gardening is compatible with square foot gardening and companion planting.
Circular waist high raised beds with a path to the center (a slice of the circle cut out) are called keyhole gardens. Often the center has a chimney of sorts built with sticks and then lined with feedbags or grasses that allows water placed at the center to flow out into the soil and reach the plants' roots. The charity 'Send a Cow' is promoting the creation of these in Africa.
Vegetable Garden Bed Construction materials should be chosen carefully. Some concerns exist over the use of timber such as Treated Pine that was traditionally treated using Chromated Copper Arsenateor CCA, a toxic chemical mix for preserving timber that may leach chemicals into the soil which in turn can be drawn up into the plants, a concern for vegetable growers, where part or all of the plant is eaten. If using timber to raise the garden bed, ensure that it is an untreated hardwood to prevent the risk of chemicals leaching into the soil. A common approach is to use timber sleepers joined with steel rods to hold them together. Another approach is to use concrete blocks, although less aesthetically pleasing, they are cheap to source and easy to use. On the market are also prefab raised garden bed solutions which are made from long lasting polyethylene that is UV stabilized and Food Grade so it isn't going to leach undesirable chemicals into your soil and it won't deteriorate in the elements. A double skinned wall provides an air pocket of insulation that minimizes the temperature fluctuations and drying out of the soil in the garden bed.

Kitchen garden

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Large-scale potager at Villandry, France
The traditional kitchen garden, also known as a potager, (in French, jardin potager) is a space separate from the rest of the residential garden - the ornamental plants and lawn areas. Most vegetable gardens are still miniature versions of old family farm plots, but the kitchen garden is different not only in its history, but also its design.
The kitchen garden may serve as the central feature of an ornamental, all-season landscape, or it may be little more than a humble vegetable plot. It is a source of herbs, vegetables, fruits, and edible flowers, but it is often also a structured garden space with a design based on repetitive geometric patterns.
The kitchen garden has year-round visual appeal and can incorporate permanent perennials or woody shrub plantings around (or among) the annuals.

Potager garden

A potager is a French term for an ornamental vegetable or kitchen garden. The historical design precedent is from the Gardens of the French Renaissance and Baroque Garden à la française eras. Often flowers (edible and non-edible) and herbs are planted with the vegetables to enhance the garden's beauty. The goal is to make the function of providing food aesthetically pleasing.
Plants are chosen as much for their functionality as for their color and form. Many are trained to grow upward. A well-designed potager can provide food, cut flowers and herbs for the home with very little maintenance. Potagers can disguise their function of providing for a home in a wide array of forms—from the carefree style of the cottage garden to the formality of a knot garden.

Vegetable garden

A small vegetable garden in May outside of Austin, Texas
A vegetable garden (also known as a vegetable patch or vegetable plot) is a garden that exists to grow vegetables and other plants useful for human consumption, in contrast to a flower garden that exists for aesthetic purposes. It is a small-scale form of vegetable growing. A vegetable garden typically includes a compost heap, and several plots or divided areas of land, intended to grow one or two types of plant in each plot. It is usually located to the rear of a property in the back garden or back yard. Many families have home kitchen and vegetable gardens that they use to produce food. In World War II, many people had a garden called a 'victory garden' which provided food to families and thus freed up resources for the war effort.
With worsening economic conditions and increased interest in organic and sustainable living, many people are turning to vegetable gardening as a supplement to their family's diet. Food grown in the back yard consumes little if any fuel for shipping or maintenance, and the grower can be sure of what exactly was used to grow it. Organic horticulture, or organic gardening, has become increasingly popular for the modern home gardener.
There are many types of vegetable gardens. The potager, a garden in which vegetables, herbs and flowers are grown together, has become more popular than the more traditional rows or blocks.

Herb garden

An herbal garden at Beernem, Belgium
The herb garden is often a separate space in the garden, devoted to growing a specific group of plants known as herbs. These gardens may be informal patches of plants, or they may be carefully designed, even to the point of arranging and clipping the plants to form specific patterns, as in a knot garden.
Herb gardens may be purely functional, or they may include a blend of functional and ornamental plants. The herbs are usually used to flavour food in cooking, though they may also be used in other ways, such as discouraging pests, providing pleasant scents, or serving medicinal purposes (e.g., a physic garden), among others.
A kitchen garden can be created by planting different herbs in pots or containers, with the added benefit of mobility. Although not all herbs thrive in pots or containers, some herbs do better than others. Mint, is an example of herb that is advisable to keep in a container or it will take over the whole garden [1].
The culinary use of herbs may result in positive medical side-effects. In addition, plants grown within the garden are sometimes specifically targeted to cure common illnesses or maladies such as colds, headaches, or anxiety. During the medieval period, monks and nuns developed specialist medical knowledge and grew the necessary herbs in specialist gardens. Now, especially due to the increase in popularity of alternative medicine, this usage is heavily increasing. Making a medicinal garden however, requires a great number of plants, one for each malady.
Herbs grown in herb gardens are also sometimes used to make herbal teas [2].
Borage is commonly grown in herb gardens; its flowers can be used as a garnish
Some popular culinary herbs in temperate climates are to a large extent still the same as in the medieval period.
Examples of herbs used for specific purposes (lists are examples only, and not intended to be complete):
However, herbs often have multiple purposes. For example, mint may be used for cooking, tea, and pest control.

Rabu, 27 Oktober 2010

Classification

Classification

Soil is classified into categories in order to understand relationships between different soils and to determine the usefulness of a soil for a particular use. One of the first classification systems was developed by the Russian scientist Dokuchaev around 1880. It was modified a number of times by American and European researchers, and developed into the system commonly used until the 1960s. It was based on the idea that soils have a particular morphology based on the materials and factors that form them. In the 1960s, a different classification system began to emerge, that focused on soil morphology instead of parental materials and soil-forming factors. Since then it has undergone further modifications. The World Reference Base for Soil Resources (WRB)[22] aims to establish an international reference base for soil classification.

Orders

Orders are the highest category of soil classification. Order types end in the letters sol. In the US classification system, there are 10 orders:[23]
  • Entisol - recently formed soils that lack well-developed horizons. Commonly found on unconsolidated sediments like sand, some have an A horizon on top of bedrock.
  • Vertisol - inverted soils. They tend to swell when wet and shrink upon drying, often forming deep cracks that surface layers can fall into.
  • Inceptisol - young soils. They have subsurface horizon formation but show little eluviation and illuviation.
  • Aridisol - dry soils forming under desert conditions. They include nearly 20% of soils on Earth. Soil formation is slow, and accumulated organic matter is scarce. They may have subsurface zones (calcic horizons) where calcium carbonates have accumulated from percolating water. Many aridiso soils have well-developed Bt horizons showing clay movement from past periods of greater moisture.
  • Mollisol - soft soils with very thick A horizons.
  • Spodosol - soils produced by podsolization. They are typical soils of coniferous and deciduous forests in cooler climates.
  • Alfisol - soils with aluminium and iron. They have horizons of clay accumulation, and form where there is enough moisture and warmth for at least three months of plant growth.
  • Ultisol - soils that are heavily leached.
  • Oxisol - soil with heavy oxide content.
  • Histosol - organic soils.
Other order schemes may include:
  • Andisols - volcanic soils, which tend to be high in glass content.
  • Gelisols - permafrost soils.
  • Organic matter

    Most living things in soils, including plants, insects, bacteria and fungi, are dependent on organic matter for nutrients and energy. Soils often have varying degrees of organic compounds in different states of decomposition. Many soils, including desert and rocky-gravel soils, have no or little organic matter. Soils that are all organic matter, such as peat (histosols), are infertile.[24]

    Humus

    Humus refers to organic matter that has decomposed to a point where it is resistant to further breakdown or alteration. Humic acids and fulvic acids are important constituents of humus and typically form from plant residues like foliage, stems and roots. After death, these plant residues begin to decay, starting the formation of humus. Humus formation involves changes within the soil and plant residue, there is a reduction of water soluble constituents including cellulose and hemicellulose; as the residues are deposited and break down, humin, lignin and lignin complexes accumulate within the soil; as microorganisms live and feed on the decaying plant matter, an increase in proteins occurs.
    Lignin is resistant to breakdown and accumulates within the soil; it also chemically reacts with amino acids which add to its resistance to decomposition, including enzymatic decomposition by microbes. Fats and waxes from plant matter have some resistance to decomposition and persist in soils for a while. Clay soils often have higher organic contents that persist longer than soils without clay. Proteins normally decompose readily, but when bound to clay particles they become more resistant to decomposition. Clay particles also absorb enzymes that would break down proteins. The addition of organic matter to clay soils, can render the organic matter and any added nutrients inaccessible to plants and microbes for many years, since they can bind strongly to the clay. High soil tannin (polyphenol) content from plants can cause nitrogen to be sequestered by proteins or cause nitrogen immobilization, also making nitrogen unavailable to plants.[25][26]
    Humus formation is a process dependent on the amount of plant material added each year and the type of base soil; both are affected by climate and the type of organisms present. Soils with humus can vary in nitrogen content but have 3 to 6 percent nitrogen typically; humus, as a reserve of nitrogen and phosphorus, is a vital component affecting soil fertility.[24] Humus also absorbs water, acting as a moisture reserve, that plants can utilize; it also expands and shrinks between dry and wet states, providing pore spaces. Humus is less stable than other soil constituents, because it is affected by microbial decomposition, and over time its concentration decreases without the addition of new organic matter. However, some forms of humus are highly stable and may persist over centuries if not millennia: they are issued from the slow oxidation of charcoal, also called black carbon, like in Amazonian Terra preta or Black Earths,[27] or from the sequestration of humic compounds within mineral horizons, like in podzols.[28]

    Climate and organics

    The production and accumulation or degradation of organic matter and humus is greatly dependent on climate conditions. Temperature and soil moisture are the major factors in the formation or degradation of organic matter, they along with topography, determine the formation of organic soils. Soils high in organic matter tend to form under wet or cold conditions where decomposer activity is impeded by low temperature[29] or excess moisture.[30]

    Soil solutions

    Soils retain water that can dissolve a range of molecules and ions. These solutions exchange gases with the soil atmosphere, contain dissolved sugars, fulvic acids and other organic acids, plant nutrients such as nitrate, ammonium, potassium, phosphate, sulfate and calcium, and micronutrients such as zinc, iron and copper. Some arid soils have sodium solutions that greatly impact plant growth. Soil pH can affect the type and amount of anions and cations that soil solutions contain and that exchange with the soil atmosphere and biological organisms.[31]

    In nature

    Biogeography is the study of special variations in biological communities. Soils are a restricting factor as to which plants can grow in which environments. Soil scientists survey soils in the hope of understanding controls as to what vegetation can and will grow in a particular location.
    Geologists also have a particular interest in the patterns of soil on the surface of the earth. Soil texture, color and chemistry often reflect the underlying geologic parent material, and soil types often change at geologic unit boundaries. Buried paleosols mark previous land surfaces and record climatic conditions from previous eras. Geologists use this paleopedological record to understand the ecological relationships in past ecosystems. According to the theory of biorhexistasy, prolonged conditions conducive to forming deep, weathered soils result in increasing ocean salinity and the formation of limestone.
    Geologists use soil profile features to establish the duration of surface stability in the context of geologic faults or slope stability. An offset subsoil horizon indicates rupture during soil formation and the degree of subsequent subsoil formation is relied upon to establish time since rupture.
    A homeowner tests soil to apply only the nutrients needed.
    Due to their thermal mass, rammed earth walls fit in with environmental sustainability aspirations.
    A homeowner sifts soil made from his compost bin in background. Composting is an excellent way to recycle household and yard wastes.
    Soil examined in shovel test pits is used by archaeologists for relative dating based on stratigraphy (as opposed to absolute dating). What is considered most typical is to use soil profile features to determine the maximum reasonable pit depth than needs to be examined for archaeological evidence in the interest of cultural resources management.
    Soils altered or formed by man (anthropic and anthropogenic soils) are also of interest to archaeologists, such as terra preta soils.

    Uses

    Soil is used in agriculture, where it serves as the primary nutrient base for plants; however, as demonstrated by hydroponics, it is not essential to plant growth if the soil-contained nutrients could be dissolved in a solution. The types of soil used in agriculture (among other things, such as the purported level of moisture in the soil) vary with respect to the species of plants that are cultivated.
    Soil material is a critical component in the mining and construction industries. Soil serves as a foundation for most construction projects. Massive volumes of soil can be involved in surface mining, road building and dam construction. Earth sheltering is the architectural practice of using soil for external thermal mass against building walls.
    Soil resources are critical to the environment, as well as to food and fiber production. Soil provides minerals and water to plants. Soil absorbs rainwater and releases it later, thus preventing floods and drought. Soil cleans the water as it percolates. Soil is the habitat for many organisms: the major part of known and unknown biodiversity is in the soil, in the form of invertebrates (earthworms, woodlice, millipedes, centipedes, snails, slugs, mites, springtails, enchytraeids, nematodes, protists), bacteria, archaea, fungi and algae; and most organisms living above ground have part of them (plants) or spend part of their life cycle (insects) belowground. Above-ground and below-ground biodiversities are tightly interconnected,[32][33] making soil protection of paramount importance for any restoration or conservation plan.
    The biological component of soil is an extremely important carbon sink since about 57% of the biotic content is carbon. Even on desert crusts, cyanobacteria lichens and mosses capture and sequester a significant amount of carbon by photosynthesis. Poor farming and grazing methods have degraded soils and released much of this sequestered carbon to the atmosphere. Restoring the world's soils could offset some of the huge increase in greenhouse gases causing global warming while improving crop yields and reducing water needs.[34][35][36]
    Waste management often has a soil component. Septic drain fields treat septic tank effluent using aerobic soil processes. Landfills use soil for daily cover. Land application of wastewater relies on soil biology to aerobically treat BOD.
    Organic soils, especially peat, serve as a significant fuel resource; but wide areas of peat production, such as sphagnum bogs, are now protected because of patrimonial interest.
    Both animals and humans in many cultures occasionally consume soil. It has been shown that some monkeys consume soil, together with their preferred food (tree foliage and fruits), in order to alleviate tannin toxicity.[37][1]
    Soils filter and purify water and affect its chemistry. Rain water and pooled water from ponds, lakes and rivers percolate through the soil horizons and the upper rock strata; thus becoming groundwater. Pests (viruses) and pollutants, such as persistent organic pollutants (chlorinated pesticides, polychlorinated biphenyls), oils (hydrocarbons), heavy metals (lead, zinc, cadmium), and excess nutrients (nitrates, sulfates, phosphates) are filtered out by the soil[38]. Soil organisms metabolize them or immobilize them in their biomass and necromass,[39] thereby incorporating them into stable humus.[40] The physical integrity of soil is also a prerequisite for avoiding landslides in rugged landscapes.[41]

    Degradation

    Land degradation[42] is a human-induced or natural process which impairs the capacity of land to function. Soils are the critical component in land degradation when it involves acidification, contamination, desertification, erosion or salination.
    While soil acidification of alkaline soils is beneficial, it degrades land when soil acidity lowers crop productivity and increases soil vulnerability to contamination and erosion. Soils are often initially acid because their parent materials were acid and initially low in the basic cations (calcium, magnesium, potassium and sodium). Acidification occurs when these elements are removed from the soil profile by normal rainfall, or the harvesting of forest or agricultural crops. Soil acidification is accelerated by the use of acid-forming nitrogenous fertilizers and by the effects of acid precipitation.
    Soil contamination at low levels is often within soil capacity to treat and assimilate. Many waste treatment processes rely on this treatment capacity. Exceeding treatment capacity can damage soil biota and limit soil function. Derelict soils occur where industrial contamination or other development activity damages the soil to such a degree that the land cannot be used safely or productively. Remediation of derelict soil uses principles of geology, physics, chemistry and biology to degrade, attenuate, isolate or remove soil contaminants to restore soil functions and values. Techniques include leaching, air sparging, chemical amendments, phytoremediation, bioremediation and natural attenuation.
    Desertification is an environmental process of ecosystem degradation in arid and semi-arid regions, often caused by human activity. It is a common misconception that droughts cause desertification. Droughts are common in arid and semiarid lands. Well-managed lands can recover from drought when the rains return. Soil management tools include maintaining soil nutrient and organic matter levels, reduced tillage and increased cover. These practices help to control erosion and maintain productivity during periods when moisture is available. Continued land abuse during droughts, however, increases land degradation. Increased population and livestock pressure on marginal lands accelerates desertification.
    Soil erosional loss is caused by wind, water, ice and movement in response to gravity. Although the processes may be simultaneous, erosion is distinguished from weathering. Erosion is an intrinsic natural process, but in many places it is increased by human land use. Poor land use practices including deforestation, overgrazing and improper construction activity. Improved management can limit erosion by using techniques like limiting disturbance during construction, avoiding construction during erosion prone periods, intercepting runoff, terrace-building, use of erosion-suppressing cover materials, and planting trees or other soil binding plants.
    A serious and long-running water erosion problem occurs in China, on the middle reaches of the Yellow River and the upper reaches of the Yangtze River. From the Yellow River, over 1.6-billion tons of sediment flow each year into the ocean. The sediment originates primarily from water erosion (gully erosion) in the Loess Plateau region of northwest China.
    Soil piping is a particular form of soil erosion that occurs below the soil surface. It is associated with levee and dam failure, as well as sink hole formation. Turbulent flow removes soil starting from the mouth of the seep flow and subsoil erosion advances upgradient.[43] The term sand boil is used to describe the appearance of the discharging end of an active soil pipe.[44]
    Soil salination is the accumulation of free salts to such an extent that it leads to degradation of soils and vegetation. Consequences include corrosion damage, reduced plant growth, erosion due to loss of plant cover and soil structure, and water quality problems due to sedimentation. Salination occurs due to a combination of natural and human caused processes. Arid conditions favor salt accumulation. This is especially apparent when soil parent material is saline. Irrigation of arid lands is especially problematic.[45] All irrigation water has some level of salinity. Irrigation, especially when it involves leakage from canals and overirrigation in the field, often raises the underlying water table. Rapid salination occurs when the land surface is within the capillary fringe of saline groundwater. Soil salinity control involves watertable control and flushing with higher levels of applied water in combination with tile drainage or another form of subsurface drainage.[46] [47]
    Soil salinity models like SWAP [48], DrainMod-S [49], UnSatChem [50], SaltMod [51] [52] and SahysMod [53] are used to assess the cause of soil salination and to optimize the reclamation of irrigated saline soils.