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 desirable traits (such as sugar concentration in a fruit) or to control the ripening process, study of the interaction between salinity and soil properties, and development of naturally salt-tolerant plant species (halophytes) into useful agricultural crops. See also halophilebacteria, which thrive under conditions of high salinity.
When properly applied (watering well in excess of evapotranspiration, maintaining soil structure for excellent drainage), brackish-water irrigation does not result in increased salinization of the soil. Sometimes this means that farmers have to add extra water after a rainstorm, to carry salts back down to below the root zone.
Salinity is the saltiness or amount of salt dissolved in a body of water, called saline water. It is usually measured in g/L or g/kg.
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 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.
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. An example of a halophyte is the salt marsh grass Spartina alterniflora. 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 the ehaloph database.
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.
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 followed by a warm dry season. They are also associated with arid conditions, areas prone to drought and those having scarce water resources.
Salsola soda, more commonly known in English as opposite-leaved saltwort, oppositeleaf Russian thistle, or barilla plant, is a small, annual, succulent shrub that is native to the Mediterranean Basin. It is a halophyte that typically grows in coastal regions and can be irrigated with salt water.
Distichlis palmeri is an obligate emergent perennial rhizomatous dioecious halophytic C4 grass in the Poacea (Gramineae) family. D. palmeri is a saltwater marsh grass endemic to the tidal marshes of the northern part of The Gulf of California and Islands section of the Sonoran Desert. D.palmeri is not drought tolerant. It does withstand surface drying between supra tidal events because roots extend downward to more than 1 meter where coastal substrata is still moist.
Atriplex semibaccata, commonly known as Australian saltbush, berry saltbush, or creeping saltbush, is a species of flowering plant in the family Amaranthaceae and is endemic to Australia. It is a perennial herb native to Western Australia, South Australia, Queensland and New South Wales, but has been introduced into other states and to overseas countries. It flowers and fruits in spring, and propagates from seed when the fruit splits open. This species of saltbush is adapted to inconsistent rainfall, temperature and humidity extremes and to poor soil. It is used for rehabilitation, medicine, as a cover crop and for fodder. Its introduction to other countries has had an environmental and economic impact on them.
Soil salinity control relates to controlling the problem of soil salinity and reclaiming salinized agricultural land. The aim of soil salinity control is to prevent soil degradation by salination and reclamation of already salty (saline) soils. Soil reclamation is also called soil improvement, rehabilitation, remediation, recuperation or amelioration.
Alkali, or Alkaline, soils are clay soils with high pH, a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell and difficult to clarify/settle. They derive their name from the alkali metal group of elements, to which sodium belongs, and which can induce basicity. Sometimes these soils are also referred to as alkaline sodic soils. Alkaline soils are basic, but not all basic soils are alkaline.
Prosopis tamarugo, commonly known as the tamarugo, is a species of flowering tree in the pea family, Fabaceae, subfamilia Mimosoideae. It is only found in northern Chile, particularly in the Pampa del Tamarugal, some 70 km (43 mi) east of the city of Iquique. This bushy tree apparently grows without the benefit of rainfall, and it is thought to obtain some water from dew. Studies indicate it is a Phreatophyte ; having deep roots that tap into ground water supplies. It also participates in hydraulic redistribution moving water from deeper levels to the upper and also reversing the process in times of severe drought.
Saltwater aquaponics is a combination of plant cultivation and fish rearing, systems with similarities to standard aquaponics, except that it uses saltwater instead of the more commonly used freshwater. In some instances, this may be diluted saltwater. The concept is being researched as a sustainable way to eliminate the stresses that are put on local environments by conventional fish farming practices who expel wastewater into the coastal zones, all while creating complementary crops.
Arthrocaulon macrostachyum, synonym Arthrocnemum macrostachyum, is a species of flowering plant in the amaranth family. It is native to coastal areas of the Mediterranean Sea and the Red Sea and parts of the Middle East, where it grows in coastal and inland salt marshes, alkali flats, and other habitats with saline soils.
Cenchrus pennisetiformis, commonly known in Australia as the Cloncurry, white or slender buffel grass, is a species of grass in the genus Cenchrus. It is native to parts of East Africa, the Arabian Peninsula and the Indian subcontinent, and has been introduced to some other parts of the world as a drought-tolerant forage crop.
International Center for Biosaline Agriculture (ICBA) is an international, not-for-profit applied agricultural research center with a unique focus on marginal environments. It identifies, tests and introduces resource-efficient, climate-smart crops and technologies that are best suited to different regions affected by salinity, water scarcity and drought. Through its work, ICBA aims to improve food security, nutrition and livelihoods of resource-poor farming communities around the world.
Salt tolerance of crops is the maximum salt level a crop tolerates without losing its productivity while it is affected negatively at higher levels. The salt level is often taken as the soil salinity or the salinity of the irrigation water.
Crop tolerance to seawater is the ability of an agricultural crop to withstand the high salinity induced by irrigation with seawater, or a mixture of fresh water and seawater. There are crops that can grow on seawater and demonstration farms have shown the feasibility. The government of the Netherlands reports a breakthrough in food security as specific varieties of potatoes, carrots, red onions, white cabbage and broccoli appear to thrive if they are irrigated with salt water.
The U.S. Salinity Laboratory is a National Laboratory for research on salt-affected soil-plant-water systems. It resorts under the Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA) and is located in Riverside, California, U.S.A.
Biosaline agriculture is the production and growth of plants in saline rich groundwater and/or soil. In water scarce locations, salinity poses a serious threat to agriculture due to its toxicity to most plants. Abiotic stressors such as salinity, extreme temperatures, and drought make plant growth difficult in many climate regions. Integration of biosaline solutions is becoming necessary in arid and semiarid climates where freshwater abundance is low and seawater is ample. Salt-tolerant plants that flourish in high-salinity conditions are called halophytes. Halophyte implementation has the potential to restore salt-rich environments, provide for global food demands, produce medicine and biofuels, and conserve fresh water.
Freshwater salinization is the process of salty runoff contaminating freshwater ecosystems, which can harm aquatic species in certain quantities and contaminate drinking water. It is often measured by the increased amount of dissolved minerals than what is considered usual for the area being observed. Naturally occurring salinization is referred to as primary salinization; this includes rainfall, rock weathering, seawater intrusion, and aerosol deposits. Human-induced salinization is termed as secondary salinization, with the use of de-icing road salts as the most common form of runoff. Approximately 37% of the drainage in the United States has been effected by salinization in the past century. The EPA has defined two thresholds for healthy salinity levels in freshwater ecosystems: 230 mg/L Cl− for average salinity levels and 860 mg/L Cl− for acute inputs.
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