superphosphate


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Related to superphosphate: bone meal, Triple superphosphate

superphosphate

or

superphosphate of lime,

Ca(H2PO4)2, is a compound produced by treating rock phosphate with sulfuric acid or phosphoric acid, or a mixture of the two. It is the principal carrier of phosphate, the form of phosphorus usable by plants, and is one of the world's most important fertilizers. Ordinary superphosphate contains about 20% available phosphate; double superphosphate (also called treble superphosphate) contains 40%–50% available phosphate.

Superphosphate

 

the most widely used mineral phosphorus fertilizer. The phosphorus in superphosphate is usually in the form of monocalcium phosphate and free phosphoric acid. The fertilizer contains gypsum and other admixtures, such as iron and aluminum phosphates, silica, and fluorine compounds. Superphosphate is obtained by the treatment of natural phosphates—apatite or phosphorite—or an apatite concentrate with sulfuric acid according to the reaction

Ca3(PO4)2 + 2H2SO4 = Ca(H2PO4)2 + 2CaSO4

Double superphosphate is derived by treating apatite or phosphorite with phosphoric acid.

Several types of superphosphate are produced industrially in the USSR. Ordinary superphosphate is a gray powder that is virtually noncaking and of average drillability; in fertilizer it provides 14–19 percent P2O5 that is available to plants. Granular superphosphate is derived from powdered superphosphate by adding moisture to it and rolling it into granules, usually 2–4 mm in diameter, in rotating drums. The granular type has a high drill-ability. Double superphosphate contains 45–48 percent available P2O5 and very little gypsum, and is usually made in granular form. Ammoniated superphosphate contains, in addition to 14–19.5 percent available P2O5, not less than 1.6 percent ammonia. Manganese superphosphate contains 1.5–2.5 percent manganese, boronated superphosphate contains 0.1–0.3 percent boron, and molybdic superphosphate contains 0.1 percent molybdenum.

Superphosphate is used in all soils as a basic presowing fertilizer; it may be applied at the time of sowing, in which case granular superphosphate is the best type, or for top dressing. It is especially effective in alkaline and neutral soils. In acidic soil the phosphoric acid of the fertilizer is converted into aluminum and iron phosphates, which are difficult for plants to assimilate. In this case, the effectiveness of the superphosphate is increased by mixing it with phosphorite flour, limestone, chalk, and humus before application to limed fields.

REFERENCES

Prianishnikov, D. N. Izbr. soch., vol. 1. Moscow, 1965.
Spravochnik po udobreniiam, 3rd ed. Moscow, 1964.
Superfosfat. Moscow, 1969. (Translated from English; edited by A. A. Sokolovskii.)

G. A. CHEREMISINOV

superphosphate

[¦sü·pər′fä‚sfāt]
(materials)
The most important phosphorus fertilizer, derived by action of sulfuric acid on phosphate rock (mostly tribasic calcium phosphate) to produce a mix of gypsum and monobasic calcium phosphate.

superphosphate

1. a mixture of the diacid calcium salt of orthophosphoric acid Ca(H2PO4)2 with calcium sulphate and small quantities of other phosphates: used as a fertilizer
2. a salt of phosphoric acid formed by incompletely replacing its acidic hydrogen atoms; acid phosphate; hydrogen phosphate
References in periodicals archive ?
However, other potential errors besides spatial variability include an overestimation of the bulk density and thus total P storage in 1979, a loss of P-rich topsoil through water and/or wind erosion that would have affected the sampled soil depth, and an erroneous P content of the superphosphate fertiliser, possibly resulting in lower P applications than planned.
Godfrey CL, Fisher FL, Norris MJ (1959) A comparison of ammonium metaphosphate and ammonium orthophosphate with superphosphate on the yield and chemical composition of crops grown under field conditions.
These processes are distinct from the temporary acidification in the vicinity of superphosphate granules, which does not directly contribute to soil acidification (Lindsay 1979).
Direct and residual effects of single superphosphate and farm yard manure on yield of cotton, sorghum and groundnuts grown in a rotation.
Poultry litter and triple superphosphate were applied to the FP plots (HP-FP and LP-FP) but only triple superphosphate for the Mix plots (HP-Mix and LP-Mix).
Lift and divide herbaceous perennials, and encourage autumnsown broad beans with a dressing of superphosphate
A light dressing of superphosphate before sowing will help to ensure well-developed roots.
In the meantime, make sure you give the ground around the fruit bushes a good light forking over and add a handful of superphosphate of lime per square yard to aid berry growth, the same of bone meal to provide slow release fertiliser over the life of the crop.
Called Bassin des Petroliers, this has two buoys for loading superphosphate and unloading of sulphur and coal.
Bioactivity of Anagallis arvensis and Calendula micrantha plants, treated with ammonium nitrate, superphosphate and potassium sulphate fertilizers, on Biomphalaria alexandrina.
c) If granulated superphosphate is added to a soil then the following crystals are formed.