Organic phosphorus bioavailability

Microbial biomass regulates storage and transformation of phosphorus, and flow of phosphorus through the soil microbial pool can be substantial. In phosphorus-limited wetlands containing significant quantities of organic phosphorus, bioavailability of phosphorus may be regulated by... 

Bjorkman, K. and Karl, D. M. (1994). Bioavailability of inorganic and organic phosphorus compounds to natural assemblages of microorganisms in Hawaiian coastal waters. Mar. Ecol. Prog. Ser. Ill, 265-273. 

Phosphorus extracted from sediment by NaOH has been related to non-occluded, surface-exchangeable, bioavailable forms (22). Hydrochloric acid extraction yields occluded phosphorus incorporated in hydrous metal oxides, carbonate and phosphate minerals of sediment. Hydroxylamine reagent specifically removes hydrous manganese oxides, while amorphous hydrous oxides of iron and aluminijm are removed by the oxalate reagent. Total available sediment phosphorus analyses includes sediment organic phosphorus components in addition to the inorganic portion determined by the selective extraction procedures. 

Bjorkman, K. M., and Karl, D. M. (2003). Bioavailability of dissolved organic phosphorus in the euphoric zone at Station ALOHA, North Pacific Subtropical Gyre. Limnol. Oceanogr. 48, 1049-1057. 

The bioavailability of iron from several organic phosphorus-containing compounds appears to be good. The iron in ferripoly-phosphate protein powder (13) and ferric glycerol phosphate Q, 6) was found to be 92-100% as bioavailable as ferrous sulfate in heme repletion assays with anemic rats and chicks. Morris and Ellis (14) have reported that the iron in monoferric phytate was utilized by rats as well as the iron in ferrous ammonium sulfate. While Lipschitz, et al. (15) have reported that dogs absorbed radio-labelled iron from a small dose (1.5 mg iron) of monoferric phytate one-half as well as they absorbed iron from ferrous sulfate. 

Sequential extraction or chemical fractionation techniques have been widely used in the characterization of various phosphorus fractions in soils and sediments, with an emphasis on the more bioavailable or plant-available inorganic forms (Condron et al., 2005). Early extraction procedures (Chang and Jackson, 1957 Williams et al., 1976b) focused on inorganic phosphorus associated with iron, aluminium and calcium, using various acid, base or salt extraction steps. Organic phosphorus was considered to be the residual or refractory phosphorus-containing fraction that remained after all other extractions had been performed. 

Pant, H.K., Reddy, K.R. and Dierberg, F.E. (2002) Bioavailability of organic phosphorus in a submerged aquatic vegetation-dominated treatment wetland. Journal of Environmental Quality... 

Turner, B.L., Cade-Menun, B.J. and Westermann, D.T. (2003a) Organic phosphorus composition and potential bioavailability in calcareous soils of the western United States. Soil Science Society of America Journal 67, 11 58-11 79. 

Studies in the tropics have reported organic phosphorus in the supernatant after resin extraction, in the sodium bicarbonate extract, in the sodium hydroxide extract before sonication, in the sodium hydroxide extract after sonication, and in the concentrated hydrochloric acid extract. Sodium bicarbonate recovers easily hydrolysable organic phosphorus (Bowman and Cole, 1978), while sodium hydroxide recovers organic phosphorus associated with humic and fulvic acids. Concentrated hydrochloric acid recovers organic phosphorus from more stable pools, although it may also extract bioavailable organic phosphorus from particulate organic matter (Tiessen and... 

Moir, 1993). Despite this, many studies have focused on organic phosphorus in bicarbonate and sodium hydroxide extracts, because these fractions are believed to become mineralized within a time frame relevant for plant growth (Cross and Schlesinger, 1995). However, it is far from clear that this is the case, and a recent study indicated that the bioavailability of organic phosphorus fractions varies depending on soil type and plant species (Chen et al., 2002). 

Several abiotic processes can regulate the bioavailability of organic phosphorus in soils and sediments. These processes include ... 

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