explain how phosphorus has redidual effect in flooded rice soils?
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The paddy soil-rice system has efficient nutrient replenishing mechanisms. Basic cations and silica are supplied by irrigation water, while biological fixation works as an inexhaustible source of N in the system, and phosphorus availability is enhanced under anaerobic conditions. This, along with almost perfect resistance to soil erosion, gives the paddy rice system high productivity as well as high sustainability.It has been shown that of the three essential macroelements, two of these, K and N, have an assured, if not sufficient, supply mechanism in paddy soils.Phosphorus has no such supply mechanism. However, it is the 11th most abundant element in the earth's crust, and is present everywhere in the soil in reasonable quantities. Therefore, what matters usually is its availability rather than the absolute quantity present. In acid soils in a humid climate, P is present mainly in the form of iron phosphate (Fe-P) and aluminum phosphate (Al-P). Neither of these is readily soluble. There are, of course, organic forms of P that may be released during the process of organic matter decomposition. However, in contrast to N, the quantity of such organic P compounds is normally very low, compared to the mineral forms of P.In the process of anaerobiosis in paddy soils, iron phosphate tends to be reduced, with a release of some of the P in available forms. Moreover, reduction of iron oxides releases some of the occluded P into the soil. Thus, there is at least one mechanism to raise the availability of P in paddy soils. The reduction of paddy soils under submerged conditions is accompanied by an elevation in soil pH. This is the result of H+ consumption as oxidized materials, such as NO3- and Fe2O3, are reduced. Usually the pH of acid paddy soils stabilizes at around 6.5. The rise in pH enhances the solubility of iron phosphate and aluminum phosphate, by a factor of 10 times per unit rise in pH.
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Phosphorus, (IPA: /ˈfɒsfərəs/, Greek: phôs meaning "light", and phoros meaning "bearer"), is the chemical element in the periodic table that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate rocks and in all living cells.\n\nPhosphorus exists in several allotropes, most commonly white, red and black. White phosphorus (P4) contains only four atoms, resulting in very high ring strain and instability. White phosphorus glows in the dark, is highly flammable and pyrophoric (self-igniting) upon contact with air as well as toxic. Red phosphorus has a network form which reduces strain and gives greater stability. Red phosphorus does not catch fire in air at temperatures below 240°C whereas white phosphorus ignites at about 40°C. Black phosphorus is amorphous and is the least reactive allotrope.\n\nRed phosphorus is formed by heating white phosphorus to 250°C (482°F) or by exposing white phosphorus to sunlight.\n\nDue to its high reactivity, phosphorus is never found as a free element in nature. It emits a faint glow upon exposure to oxygen (hence its Greek derivation and the Latin meaning 'morning star') and is an essential element for living organisms. The most important commercial use of phosphorus-based chemicals is the production of fertilizers. They are also widely used in explosives, nerve agents, friction matches, fireworks, pesticides, toothpaste, and detergents.\n\nContents [hide]\n1 Characteristics \n1.1 Glow \n2 Applications \n3 Biological role \n4 History \n5 Occurrence \n6 Precautions \n7 Isotopes \n8 Spelling \n9 Compounds \n10 References \n11 External links \n \n\n\n[edit] Characteristics\nPhosphorus, in its common form, is a waxy white (or yellowish) solid that has a characteristic, disagreeable smell similar to that of garlic. Pure forms of the element are colorless and transparent. This nonmetal is not soluble in water, but is soluble in carbon disulfide. The white allotrope ignites spontaneously in air; however both white and red phosphorus burn in air to produce phosphorus pentoxide.\n\n\n[edit] Glow\nThe glow from phosphorus was the attraction of its discovery around 1669, but the mechanism for that glow was not fully described until 1974.[1] It was known from early times that the glow would persist for a time in a stoppered jar but then cease. Robert Boyle in the 1680s ascribed it to "debilitation" of the air. In fact it is oxygen being consumed. By the 18th century it was known that in pure oxygen phosphorus does not glow at all,[2] there is only a range of partial pressure where it does, too high or too low and the reaction stops. Heat can be applied to drive the reaction at higher pressures.[3]\n\nIn 1974 the glow was explained by R. J. van Zee and A. U. Khan.[1] A reaction with oxygen takes place at the surface of the solid (or liquid) phosphorus, forming short-lived molecules HPO and P2O2 and they both emit visible light. The reaction is slow and only very little of the intermediates is required to produce the luminescence, hence the extended time the glow continues in a stoppered jar.\n\nAlthough the term phosphorescence is derived from phosphorus, the reaction is properly called luminescence (glowing by its own reaction, in this case chemoluminescence), not phosphorescence (re-emitting light that previously fell on it).\n\n\n[edit] Applications\nConcentrated phosphoric acids, which can consist of 70% to 75% P2O5 are very important to agriculture and farm production in the form of fertilizers. Global demand for fertilizers led to large increases in phosphate (PO43-) production in the second half of the 20th century. Other uses;\n\nPhosphates are utilized in the making of special glasses that are used for sodium lamps. \nBone-ash, calcium phosphate, is used in the production of fine china. \nSodium tripolyphosphate made from phosphoric acid is used in laundry detergents in sev
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http://www.indiana.edu/~bradwood/eagles/phosphate.htm\n\nhttp://pronet-internet.merck.de/Attachment/17795.ProNet.pdf?file
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The last answer is correct.\n\nLimestone acts to raise the pH of the soil. It is basic which means it is on the base end of the pH scale.\n\nThe reason limestone is a base is b/c of its composition. Limestone is calcium carbonate or CaCO3. The calcium is the base.\n\nIf you are interested in learning more about soil pH & other factors affecting soil, check out the link to the US Dept. of Agriculture.
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Most detergents have already reduced phosphate levels to below requested minimums. I think you have a stale worry and need to upgrade your worry list.
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nitrogen fixation\n\nNot sure about the details, but I think that fungi or bacteria on plant's roots do this.
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2 HNO3(aq) + Sr(OH)2(aq) --> Sr(NO3)2 (aq) + 2 H2O\n\n2 H3PO4(aq) + 3 Ba(OH)2(aq) --> Ba3(PO4)2 (cr)* + 6 H2O\n\n* Barium Phosphate will precipiate out of an aqueous solution in this reaction
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The soil is very iron-rich. When iron oxidizes, it produces iron oxide which is basically rust and it red in color. :)\n\nAnd interesting side fact, the dawn and dusk sky is blue. (It's reddish on Earth :)
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Some soil is lost with the harvesting of the sod.  This is replaced when necessary.
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Concrete can affect the ph of soil and water that it comes in contact with. The larger the body of water, the less potential effect.
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Here's a link for the nitrogen cycle that has a diagram. \nhttp://muextension.missouri.edu/xplor/envqual/wq0252.htm\nBasically nitrogen goes from plants to animals to the ground from waste and is broken down by bacteria.\n\nHere's a good link that explains the phosphorous cycle. Basically, the phosphorous cycle is when phosphorous is in water from broken down rock sediment and in plants, is consumed and used in animal, then is returned to the environment through decomposers.\n\nThe carbon cycle is when carbon from the air is used by plants and animals in respiration and returned to the environment in respiration and decomposition.\n\nHere's another link that may help.\nhttp://neptune.gsfc.nasa.gov/STAFF/brianc/phospho.html
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In order for a plant to grow and thrive, it needs a number of different chemical elements.\nThe most important of these (the ones that are needed in the largest quantity by a plant) are nitrogen, phosphorus and potassium. \nWithout nitrogen, phosphorus and potassium, the plant simply cannot grow because it cannot make the pieces it needs\nTo make plants grow faster, what you need to do is supply the elements that the plants need in readily available forms. That is the goal of fertilizer. Most fertilizers supply just nitrogen, phosphorus and potassium because the other chemicals are needed in much lower quantities and are generally available in most soils. Nitrogen, phosphorus and potassium availability is the big limit to growth. \n\nAre you aware that plants need at least sixteen elements for healthy growth and that only four of them are commonly applied as fertilizer? These four are calcium, phosphorus, nitrogen and potassium. \n\nThe numbers on a bag of fertilizer tell you the percentages of available nitrogen, phosphorus and potassium found in the bag. So 12-8-10 fertilizer has 12-percent nitrogen, 8-percent phosphorous and 10-percent potassium. In a 100-pound bag, therefore, 12 pounds is nitrogen, 8 pounds is phosphorous and 10 pounds is potassium. The other 70 pounds is known as ballast and has no value to the plants. \n\nThere are many forms of fertilizers, and from my vast experience in growing shrubs, plants and garden crops I have not found a particular advantage of using the liquid over the dry: it is perhaps a matter of personal preference. The dry forms of fertilizer seem to work best on starter plants and are also excellent for accurate application to houseplants and other container grown plants.
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Nitrogen gets into the soil from manure, fertilizer. Plants such as clover, alfalfa, and soybeans put nitrogen into the soil from the air.
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when the rain season comes it makes the niles banks flood with water which for the farmers is actually a good thing because the ni le has a lot of nutrients and sediments in its soil and rocks so when it gets on shore it serves as a fertilizer for the plants ! ! ! ! !
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First,the field is ploughed with the help of buffaloes or tractors,and flooded with water.Then,rice seeds are scattered onto a dry field(called a nursery) where they sprout into seedlings.They are then transplanted to the flooded rice fiels(padi fields) where they grow into rice plants.After that,after about 100 to 150 days(depends on which type of rice),they are harvested with sickles or more modern methods.
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ammonia is what they get phosphorus out of .
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http://natres.psu.ac.th/Link/SoilCongress/bdd/symp9/1375-t.pdf