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Drainage (agriculture)
An agricultural drainage system is a system by which water is drained on or in the soil to enhance agricultural production of crops. It may involve any combination of stormwater control, erosion control, and watertable control. Classification While there are more than two types of drainage systems employed in agriculture, there are two main types: (1) surface drainage and (2) sub-surface drainage. Figure 1 classifies the various types of drainage systems. It shows the field (or internal) and the main (or external) systems. The function of the ''field drainage system'' is to control the water table, whereas the function of the ''main drainage system'' is to collect, transport, and dispose of the water through an outfall or outlet. In some instances one makes an additional distinction between collector and main drainage systems. Field drainage systems are differentiated in surface and subsurface field drainage systems. Sometimes (e.g., in irrigated, submerged rice fields), a form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, despite not providing food, energy or organic micronutrients. Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is also the name of the liquid state of H2O at standard temperature and pressure. A number of natural states of water exist. It forms precipitation in the form of rain and aerosols in the form of fog. Clouds consist of suspended droplets of water and ice, its solid state. When finely divided, crystalline ice may precipitate in the form of snow. The gaseous state of water is steam or water vapor. Water co ... [...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] |
Sub-soiling
A subsoiler or flat lifter is a tractor-mounted farm implement used for deep tillage, loosening and breaking up soil at depths below the levels worked by moldboard ploughs, disc harrows, or rototillers. Most such tools will break up and turn over surface soil to a depth of , whereas a subsoiler will break up and loosen soil to twice those depths. The subsoiler is a tillage tool which will improve growth in all crops where soil compaction is a problem. In agriculture angled wings are used to lift and shatter the hardpan that builds up due to compaction. The design provides deep tillage, loosening soil deeper than a tiller or plough is capable of reaching. Agricultural subsoilers, according to the Unverferth Company, can disrupt hardpan ground down to depths. The subsoiler consists of three or more heavy vertical shanks (standards) mounted on a toolbar or frame with shear bolts. They can be operated at depths of or more. A ripper normally runs deep. Shanks are curved and have re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deep Plowing
Deep plowing is a plowing to a depth greater than 50 cm (20 in) as compared to ordinary plowing which rarely exceeds 20 cm (8 in). The purpose of deep plowing is to modify the soil water retention characteristics over the long term. In one long-term test, lasting 35 years, the mean annual grain yield was 2,800 lbs per acre (3,138 kg per ha) with deep plowing, which was 10% greater than the 2,550 lbs per acre (2,858 kg per ha) yield in unplowed plots. Under certain conditions, it is recommended to use deep plowing in preparing the soil for planting new vineyards. There is a movement away from plowing altogether and from deep plowing in particular. The theory is that this will stop the loss of topsoil, increase the organic content of soil and reduce runoff of fertilizer and pesticides into rivers. Another part of the no-plowing theory is that ground moisture would be conserved; but this was shown to be incorrect by a 35-year study. See a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A NEW DRAIN PIPE-ENVELOPE CONCEPT FOR SUBSURFACE DRAINAGE SYSTEMS IN IRRIGATED AGRICULTURE
A, or a, is the first letter and the first vowel of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''a'' (pronounced ), plural ''aes''. It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version can be written in two forms: the double-storey a and single-storey ɑ. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. In English grammar, " a", and its variant " an", are indefinite articles. History The earliest certain ancestor of "A" is aleph (also written 'aleph), the first letter of the Phoenician alphabet, which consisted entirely of consonants (for that reason, it is also called an abjad to distinguish it fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geotextile
Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in two basic forms: woven (resembling mail bag sacking) and nonwoven (resembling felt). Geotextile composites have been introduced and products such as geogrids and meshes have been developed. Geotextiles are durable and are able to soften a fall. Overall, these materials are referred to as geosynthetics and each configuration—geonets, geosynthetic clay liners, geogrids, geotextile tubes, and others—can yield benefits in geotechnical and environmental engineering design. History Geotextiles were originally intended to be a substitute for granular soil filters. The original, and still sometimes used, term for geotextiles is ''filter fabrics''. Work originally began in the 1950s with R.J. Barrett using geotextiles behind precast concrete seawalls, under precast c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthetic Fibre
Synthetic fibers or synthetic fibres (in British English; see spelling differences) are fibers made by humans through chemical synthesis, as opposed to natural fibers that are directly derived from living organisms, such as plants (like cotton) or fur from animals. They are the result of extensive research by scientists to replicate naturally occurring animal and plant fibers. In general, synthetic fibers are created by extruding fiber-forming materials through spinnerets, forming a fiber. These are called synthetic or artificial fibers. The word polymer comes from a Greek prefix "poly" which means "many" and suffix "mer" which means "single units". (Note: each single unit of a polymer is called a monomer). Early experiments The first fully synthetic fiber was glass. Joseph Swan invented one of the first artificial fibers in the early 1880s; today it would be called semisynthetic in precise usage. His fiber was drawn from a cellulose liquid, formed by chemically modifying th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silty
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when dry, and lacks plasticity when wet. Silt also can be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles). Silt is a common material, making up 45% of average modern mud. It is found in many river deltas and as wind-deposited accumulations, particularly in central Asia, north China, and North America. It is produced in both very hot climates (through such processes as collisions of quartz grains in dust storms) and very cold climates (through such processes as glacial grinding of quartz grains.) Loess is soil rich in silt which makes up some of the most fertile agricultural land on Earth. However, silt is very vulnerable to erosion, and it has poor mechanical properties, making construction o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand, for example, aragonite, which has mostly been created, over the past 500million years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Somewhat more rarely, sand may be composed of calciu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filtration
Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filter medium are described as ''oversize'' and the fluid that passes through is called the ''filtrate''. Oversize particles may form a filter cake on top of the filter and may also block the filter lattice, preventing the fluid phase from crossing the filter, known as ''blinding''. The size of the largest particles that can successfully pass through a filter is called the effective ''pore size'' of that filter. The separation of solid and fluid is imperfect; solids will be contaminated with some fluid and filtrate will contain fine particles (depending on the pore size, filter thickness and biological activity). Filtration occurs both in nature and in engineered systems; there are biological, geological, and industrial forms. Filtration is als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tile Drainage
Tile drainage is a form of agricultural drainage system that removes excess sub-surface water from fields to allow sufficient air space within the soil, proper cultivation, and access by heavy machinery to tend and harvest crops. While surface water can be drained by pumping, open ditches, or both, tile drainage is often the most effective means of draining subsurface water. The phrase "tile drainage" derives from its original composition from ceramic tiles of fired clay, which were similar to terracotta pipes yet not always shaped as pipes. In the 19th century a "C" shaped channel tile commonly was placed like an arch atop a flat tile, denominated the "mug" and "sole", respectively. Today, tile drainage is any variation of this original system that functions in the same mode. Commonly HDPE and PVC tubing denominated "tile line" is used, although precast concrete and ceramic tiles are still used. Typical pathways for agricultural drainage and the occasionally used pathways for tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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