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Biosalinity
Biosalinity is the study and practice of using saline (salty) water for irrigating agricultural crops. Many arid and semi-arid areas actually do have sources of water, but the available water is usually brackish (0.5–5g/L salt) or saline (30–50g/L salt). The water may be present in underground aquifers or as seawater along coastal deserts. With traditional farming practices, saline water results in soil salinization, rendering it unfit for raising most crop plants. Indeed, many arid and semi-arid areas were simply considered unsuitable for agriculture, and agricultural development of these areas was not systematically attempted until the second half of the 20th century. Research in biosalinity includes studies of the biochemical and physiological mechanisms of salt tolerance in plants, breeding and selection for salt tolerance (halotolerance), discovery of periods in a crop plant's life cycle when it may be less sensitive to salt, use of saline irrigation water to increase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Salinity
Soil salinity is the salt content in the soil; the process of increasing the salt content is known as salinization. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean. It can also come about through artificial processes such as irrigation and road salt. Natural occurrence Salts are a natural component in soils and water. The ions responsible for salination are: Na+, K+, Ca2+, Mg2+ and Cl−. Over long periods of time, as soil minerals weather and release salts, these salts are flushed or leached out of the soil by drainage water in areas with sufficient precipitation. In addition to mineral weathering, salts are also deposited via dust and precipitation. Salts may accumulate in dry regions, leading to naturally saline soils. This is the case, for example, in large parts of Australia. Human practices can increase the salinity of soils by the addition of salts in i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halotolerance
Halotolerance is the adaptation of living organisms to conditions of high salinity. Halotolerant species tend to live in areas such as hypersaline lakes, coastal dunes, saline deserts, salt marshes, and inland salt seas and springs. Halophiles are organisms that live in highly saline environments, and require the salinity to survive, while halotolerant organisms (belonging to different domains of life) can grow under saline conditions, but do not require elevated concentrations of salt for growth. Halophytes are salt-tolerant higher plants. Halotolerant microorganisms are of considerable biotechnological interest. Applications Fields of scientific research relevant to halotolerance include biochemistry, molecular biology, cell biology, physiology, ecology, and genetics. An understanding of halotolerance can be applicable to areas such as arid-zone agriculture, xeriscaping, aquaculture (of fish or algae), bioproduction of desirable compounds (such as phycobiliproteins or carotenoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root '' brak''. Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment (see article on shrimp farms). Technically, brackish water contains between 0.5 and 30 grams of salt per litre—more often expressed as 0.5 to 30 parts per thousand (‰), which is a specific grav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arid-zone Agriculture
Dryland farming and dry farming encompass specific agricultural techniques for the non-irrigated cultivation of crops. Dryland farming is associated with drylands, areas characterized by a cool wet season (which charges the soil with virtually all the moisture that the crops will receive prior to harvest) followed by a warm dry season. They are also associated with arid conditions, areas prone to drought and those having scarce water resources. Process Dryland farming has evolved as a set of techniques and management practices used by farmers to continually adapt to the presence or lack of moisture in a given crop cycle. In marginal regions, a farmer should be financially able to survive occasional crop failures, perhaps for several years in succession. Survival as a dryland farmer requires careful husbandry of the moisture available for the crop and aggressive management of expenses to minimize losses in poor years. Dryland farming involves the constant assessing of the am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halophile
The halophiles, named after the Greek word for "salt-loving", are extremophiles that thrive in high salt concentrations. While most halophiles are classified into the domain Archaea, there are also bacterial halophiles and some eukaryotic species, such as the alga ''Dunaliella salina'' and fungus ''Wallemia ichthyophaga''. Some well-known species give off a red color from carotenoid compounds, notably bacteriorhodopsin. Halophiles can be found in water bodies with salt concentration more than five times greater than that of the ocean, such as the Great Salt Lake in Utah, Owens Lake in California, the Urmia Lake in Iran, the Dead Sea, and in evaporation ponds. They are theorized to be a possible analogues for modeling extremophiles that might live in the salty subsurface water ocean of Jupiter's Europa and similar moons. Classification Halophiles are categorized by the extent of their halotolerance: slight, moderate, or extreme. Slight halophiles prefer 0.3 to 0.8 M (1.7 to 4.8%†... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halophyte
A halophyte is a salt-tolerant plant that grows in soil or waters of high salinity, coming into contact with saline water through its roots or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs and seashores. The word derives from Ancient Greek ἅλας (halas) 'salt' and φυτόν (phyton) 'plant'. Halophytes have different anatomy, physiology and biochemistry than glycophytes.Physiology of halophytes, T. J. FLOWERS, Plant and Soil 89, 41-56 (1985) An example of a halophyte is the salt marsh grass ''Spartina alterniflora'' (smooth cordgrass). Relatively few plant species are halophytes—perhaps only 2% of all plant species. Information about many of the earth's halophytes can be found in thehalophdatabase. The large majority of plant species are glycophytes, which are not salt-tolerant and are damaged fairly easily by high salinity. Classification Halophytes can be classified in many ways. According to Stocker (1933), it is mainly of 3 kin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double sugars, are molecules made of two bonded monosaccharides; common examples are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (two molecules of glucose). White sugar is a refined form of sucrose. In the body, compound sugars are hydrolysed into simple sugars. Longer chains of monosaccharides (>2) are not regarded as sugars, and are called oligosaccharides or polysaccharides. Starch is a glucose polymer found in plants, the most abundant source of energy in human food. Some other chemical substances, such as glycerol and sugar alcohols, may have a sweet taste, but are not classified as sugar. Sugars are found in the tissues of most plants. Honey and fruits are abundant natural sources of simple sugars. Suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Structure
Soil structure describes the arrangement or the way of soil in the solid parts of the soil and of the pore space located between them. It is determined by how individual soil granules clump, bind together, and aggregate, resulting in the arrangement of soil pores between them. Soil has a major influence on water and air movement, biological activity, root growth and seedling emergence. There are several different types of soil structure. It is inherently a dynamic and complex system that is affected by different factors. Overview Soil structure describes the arrangement of the solid parts of the soil and of the pore spaces located between them (Marshall & Holmes, 1979). Aggregation is the result of the interaction of soil particles through rearrangement, flocculation and cementation. It is enhanced by: the precipitation of oxides, hydroxides, carbonates and silicates; the products of biological activity (such as biofilms, fungal hyphae and glycoproteins); ionic bridging between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evapotranspiration
Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpiration (movement of water from the soil, through roots and bodies of vegetation, on leaves and then into the air). Evapotranspiration is an important part of the local water cycle and climate, as well as measurement of it plays a key role in agricultural irrigation and water resource management. Definition Evapotranspiration is a combination of evaporation and transpiration, measured in order to better understand crop water requirements, irrigation scheduling, and watershed management. The two key components of evapotranspiration are: * Evaporation: the movement of water directly to the air from sources such as the soil and water bodies. It can be affected by factors including heat, humidity, and wind speed. * Transpiration: the move ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacterium
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in symbiotic and parasitic relationshi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former term specifically to displaced soil. Soil consists of 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ‰). Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water. A contour line of constant salinity is called an ''isohaline'', or sometimes ''isohale''. Definitions Salinity in rivers, lakes, and the ocean is conceptually simple, but technically challenging to define and measure precisely. Conceptually the salinity is the quantity of dissolved salt content of the water. Salts are compounds like sodium chloride, magnesium sulfate, potassium nitrate, and sodium bicarbonate which dissolve into ions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
