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Soil Salinity
Soil salinity is the salt (chemistry), salt content in the soil; the process of increasing the salt content is known as salinization (also called salination in American and British English spelling differences, American English). Salts occur naturally within soils and water. Salinization 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 Sodium_chloride#Road_salt, road salt. Natural occurrence Salt (chemistry), Salts are a natural component in soils and water. The ions responsible for salinization are: Sodium, Na+, Potassium, K+, Calcium, Ca2+, Magnesium, Mg2+ and Chlorine, Cl−. Over long periods of time, as soil minerals weathering, 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 precipitatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salinity
Salinity () is the saltiness or amount of salt (chemistry), 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 per mille, ‰). Salinity is an important factor in determining many aspects of the chemistry of natural waters and of biological processes within it, and is a state function, 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 sod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Egypt
Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northern coast of Egypt, the north, the Gaza Strip of Palestine and Israel to Egypt–Israel barrier, the northeast, the Red Sea to the east, Sudan to Egypt–Sudan border, the south, and Libya to Egypt–Libya border, the west; the Gulf of Aqaba in the northeast separates Egypt from Jordan and Saudi Arabia. Cairo is the capital, list of cities and towns in Egypt, largest city, and leading cultural center, while Alexandria is the second-largest city and an important hub of industry and tourism. With over 109 million inhabitants, Egypt is the List of African countries by population, third-most populous country in Africa and List of countries and dependencies by population, 15th-most populated in the world. Egypt has one of the longest histories o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ion Toxicity
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convention. The net charge of an ion is not zero because its total number of electrons is unequal to its total number of protons. A cation is a positively charged ion with fewer electrons than protons (e.g. K+ (potassium ion)) while an anion is a negatively charged ion with more electrons than protons (e.g. Cl− (chloride ion) and OH− (hydroxide ion)). Opposite electric charges are pulled towards one another by electrostatic force, so cations and anions attract each other and readily form ionic compounds. Ions consisting of only a single atom are termed ''monatomic ions'', ''atomic ions'' or ''simple ions'', while ions consisting of two or more atoms are termed polyatomic ions or ''molecular ions''. If only a + or − is present, it indicate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also Crystallization, crystallizes as translucent crystals of selenite (mineral), selenite. It forms as an evaporite mineral and as a Mineral hydration, hydration product of anhydrite. The Mohs scale of mineral hardness defines gypsum as hardness value 2 based on Scratch hardness, scratch hardness comparison. Fine-grained white or lightly tinted forms of gypsum known as alabaster have been used for sculpture by many cultures including Ancient Egypt, Mesopotamia, Ancient Rome, the Byzantine Empire, and the Nottingham alabasters of Medieval England. Etymology and history The word ''wikt:gypsum, gypsum'' is derived from the Greek language, Greek word (), "plaster". Because the quarry, quarries of the Montmartre district of P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Land Reclamation
Land reclamation, often known as reclamation, and also known as land fill (not to be confused with a waste landfill), is the process of creating new Terrestrial ecoregion, land from oceans, list of seas, seas, Stream bed, riverbeds or lake beds. The land reclaimed is known as reclamation ground, reclaimed land, or land fill. History In ancient Egypt, the rulers of the Twelfth Dynasty of Egypt, Twelfth Dynasty (c. 2000–1800 BC) undertook a far-sighted land reclamation scheme to increase agricultural output. They constructed levees and canals to connect the Faiyum Oasis, Faiyum with the Bahr Yussef waterway, diverting water that would have flowed into Lake Moeris and causing gradual evaporation around the lake's edges, creating new farmland from the reclaimed land. A similar land reclamation system using dams and drainage canals was used in the Greek Lake Copais, Copaic Basin during the Middle Helladic period, Middle Helladic Period (c. 1900–1600 BC). Another early large-s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizosphere
The rhizosphere is the narrow region of soil or Substrate (biology), substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Pore space in soil, Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed ''rhizodeposition'', and the proteins and sugars released by roots, termed Root mucilage, root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycle, nutrient cycling and disease suppression by antibiotics required by plants occurs immediately adjacent to roots due to root exudates and metabolism, metabolic products of symbiotic and Plant pathology, pathogenic communities of microorganisms. The rhizosphere also provides space to produce Allelopathy, allelochemicals to control neighbours and relatives. The ''rhizoplane'' refers to the root surface including it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum
Molybdenum is a chemical element; it has Symbol (chemistry), symbol Mo (from Neo-Latin ''molybdaenum'') and atomic number 42. The name derived from Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm. Molybdenum does not occur naturally as a Native metal, free metal on Earth; in its minerals, it is found only in oxidation state, oxidized states. The free element, a silvery metal with a grey cast, has the List of elements by melting point, sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of the world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys. Most molybdenum ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron
Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride. Boron is synthesized entirely by cosmic ray spallation and supernovas and not by stellar nucleosynthesis, so it is a low-abundance element in the Solar System and in the Earth's crust. It constitutes about 0.001 percent by weight of Earth's crust. It is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known deposits are in Turkey, the largest producer of boron minerals. Elemental boron is found in smal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Infiltration
Infiltration is the process by which water on the ground surface enters the soil. It is commonly used in both hydrology and soil sciences. The infiltration capacity is defined as the maximum rate of infiltration. It is most often measured in meters per day but can also be measured in other units of distance over time if necessary. The infiltration capacity decreases as the soil moisture content of soils surface layers increases. If the precipitation rate exceeds the infiltration rate, runoff will usually occur unless there is some physical barrier. Infiltrometers, parameters and rainfall simulators are all devices that can be used to measure infiltration rates. Infiltration is caused by multiple factors including; gravity, capillary forces, adsorption, and osmosis. Many soil characteristics can also play a role in determining the rate at which infiltration occurs. Factors that affect infiltration Precipitation Precipitation can impact infiltration in many ways. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkaline Soil
Alkali, or alkaline, soils are clay soils with high Soil pH, pH (greater than 8.5), 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 Physical chemistry, physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell 16), in contact with non-saline soil moisture have an expanded DDL zone and the soil swells (dispersion (geology), dispersion). The phenomenon results in deterioration of the soil structure, and especially crust formation and compaction of the top layer. Hence the infiltration capacity of the soil and the water availability in the soil is reduced, whereas the surface-water-logging or surface runoff is increased. Seedling emergence and crop production are badly affected. :''Note'': :* Under saline conditions, the many ions in the soil solution counteract the swelling of the soil, so that saline soils usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acidic Soil
Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the negative logarithm (base 10) of the activity of hydronium ions ( or, more precisely, ) in a solution. In soils, it is measured in a slurry of soil mixed with water (or a salt solution, such as ), and normally falls between 3 and 10, with 7 being neutral. Acid soils have a pH below 7 and alkaline soils have a pH above 7. Ultra-acidic soils (pH 9) are rare. Soil pH is considered a master variable in soils as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of the different nutrients and influencing the chemical reactions they undergo. The optimum pH range for most plants is between 5.5 and 7.5; however, many plants have adapted to thrive at pH values ou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arable Land
Arable land (from the , "able to be ploughed") is any land capable of being ploughed and used to grow crops.''Oxford English Dictionary'', "arable, ''adj''. and ''n.''" Oxford University Press (Oxford), 2013. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition: A more concise definition appearing in the Eurostat glossary similarly refers to actual rather than potential uses: "land worked (ploughed or tilled) regularly, generally under a system of crop rotation". In Britain, arable land has traditionally been contrasted with pasturable land such as heaths, which could be used for sheep-rearing but not as farmland. Arable land is vulnerable to land degradation and some types of un-arable land can be enriched to create useful land. Climate change and biodiversity loss are driving pressure on arable land. By country According to the Food and Agriculture Organization of the United Nations, in 2013, the world's arable land amo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
