I want a research paper for a suggested fractionation Scheme of phosphorus in calcareous soils?
Here are some good research papers on phosphorous fractionation in calcareous soils :
Phosphorus fractionated to NaCl+NaOH-P, citrate bicarbonate (CB-P), citrate bicarbonate dithionate (CBD-P), acetic acid-sodium acetate (OAc)and HCl (HCl–P) after5, 30 and 150 days. Olsen-P, in P-treated soils, showed a positive correlationwith the NH4OAc extractable Al and active CaCO3. Increases in recovery as CBD-P revealed that Fe oxides play an importantroleinPsorptionduring0–30days.TherelativedistributionofPfractionsandOlsen-Pfollowedthe order of HCl–PNOAc-PNOrganic-PNCBD-PNOlsen-PNNaCl-NaOH-P ( PDF enclosed).
Another studies by Sharplay and Smith (1985, Soil Sci.Soc.Am.J. , 49: 126-132) showed , distribution of inorganic P in virgin noncalcareous soils was, on average, 2% loosely-bound, 52% nonoccluded, and 46% occluded. Cultivation resulted in an increase in nonoccluded and decrease in occluded P. Average distribution in the virgin calcareous soils was 2% loosely-bound, 11% nonoccluded, 9% occluded, and 78% Ca-bound, with no significant change in pool size with cultivation observed. On average, organic P in the virgin soils was 7% labile, 48% moderately labile, 33% moderately resistant, and 12% resistant, with no significant change in relative amounts due to cultivation. Amounts of fertilizer P applied and organic P mineralized and immobilized in stable inorganic P pools during cultivation, were related to P sorption index of the soils. The conversion of organic to inorganic P may be reversed by management practices allowing a build up of soil organic matter (PDF enclosed).
Hope , you like both PDFs.
Dr.Amin,the most commonly used method for fractionation of P in recent times is the procedure suggested by Hedley et al.(1982).The fractionation scheme separates the P in to labile(organic and inorganic), moderately labile(organic and inorganic) and nonlabile inorganic P(Ca-bound P) ,The following references may be consulted.
Hedley MJ,Stewart JWB and Chauhan BS(1982) Changes in inorganic soil phosphorus fractions induced by cultivation practices and by laboratory incubation. Soil Sci.Soc.Am .46:970-976.J.
Transformations of fertilizer P in a Vertisol amended with farmyard manure. Sammi Reddy K ,Subba Rao A. and Takkar PN(1996)Biol. Fertil. Soils 22:279-282.
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