Identification of inositol hexakisphosphate binding sites in soils by selective extraction and solution 31P NMR spectroscopy

Jørgensen, Charlotte Adam; Turner, Benjamín L.; Reitzel, Kasper

doi:10.1016/j.geoderma.2015.03.021

Cited by 39 publications

(15 citation statements)

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“…Myo-inositol hexakisphosphate (IP 6 , phytic acid) is the most prevalent form and this might therefore account for much of the P in NRSOM, if it is assumed that it comprises about 3 % of the total mass as in the illustrative three-component mixture (see ''Results'' section). However, to attribute all of the P in NRSOM to IP 6 is likely too much of a simplification, since reasons for variation in the IP 6 contents of soils remain elusive (Turner et al 2012;Jørgensen et al 2015).…”

Section: Discussionmentioning

confidence: 99%

The C:N:P:S stoichiometry of soil organic matter

Tipping¹,

2016

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The formation and turnover of soil organic matter (SOM) includes the biogeochemical processing of the macronutrient elements nitrogen (N), phosphorus (P) and sulphur (S), which alters their stoichiometric relationships to carbon (C) and to each other. We sought patterns among soil organic C, N, P and S in data for c. 2000 globally distributed soil samples, covering all soil horizons. For non-peat soils, strong negative correlations (p \ 0.001) were found between N:C, P:C and S:C ratios and % organic carbon (OC), showing that SOM of soils with low OC concentrations (high in mineral matter) is rich in N, P and S. The results can be described approximately with a simple mixing model in which nutrient-poor SOM (NPSOM) has N:C, P:C and S:C ratios of 0.039, 0.0011 and 0.0054, while nutrient-rich SOM (NRSOM) has corresponding ratios of 0.12, 0.016 and 0.016, so that P is especially enriched in NRSOM compared to NPSOM. The trends hold across a range of ecosystems, for topsoils, including O horizons, and subsoils, and across different soil classes. The major exception is that tropical soils tend to have low P:C ratios especially at low N:C. We suggest that NRSOM comprises compounds selected by their strong adsorption to mineral matter. The stoichiometric patterns established here offer a new quantitative framework for SOM classification and characterisation, and provide important constraints to dynamic soil and ecosystem models of carbon turnover and nutrient dynamics.

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Section: Discussionmentioning

confidence: 99%

The C:N:P:S stoichiometry of soil organic matter

Tipping¹,

2016

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“…Organic phosphorus (OPs) often accounts for as much as 50–80% of total soil P (Turner, Papházy, Haygarth, & McKelvie, ) and myo ‐inositol hexakisphosphate (IHP or phytate) can represent up to 45% of OPs (Gerke, ). The preferential accumulation of IHP in soils is attributed to its strong interaction with soil minerals, especially with iron/aluminium (Fe/Al) oxides (Celi, De Luca, & Barberis, ; Celi, Presta, Ajmore‐Marsan, & Barberis, ; Guan, Shang, Zhu, & Chen, ; Jørgensen, Turner, & Reitzel, ; Yan et al, ; Yan et al, ), which limits IHP biodegradation and bioavailability. However, the classical assumption on the longer residence of IHP in soils than other P forms has been questioned recently (Doolette, Smernik, & Dougherty, ; Stout, Nguyen, & Jaisi, ).…”

Section: Introductionmentioning

confidence: 99%

Adsorption and precipitation of myo‐inositol hexakisphosphate onto kaolinite

Jaisi

Yan

et al. 2019

European J Soil Science

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Sorption of myo‐inositol hexakisphosphate (IHP), a common type of organic phosphorus in soils, largely controls its mobility and bioavailability. Research on the interaction between IHP and phyllosilicate minerals such as kaolinite, which is commonly present in highly weathered soils, has often been neglected, probably due to the common assumption that negatively charged phyllosilicate minerals have low sorption capacity and binding affinity to IHP and thus do not play any significant role in its fate. Here, the interaction between IHP and poorly crystallized kaolinite (KGa‐2) was investigated in batch experiments using Zeta (ζ) potential measurement and 31P nuclear magnetic resonance (NMR) spectroscopy. The results showed that dissolved Al(III) concentration at the adsorption initiation stage increased with increasing IHP concentration at pH 4.0. From pH 2.5 to 9.0, IHP presented a maximum sorption capacity (50 μmol g−1) at pH 4.0 at 24 hr. With IHP sorption, the ζ potential of kaolinite first decreased sharply to a negative value, then gradually increased with resorption of Al(III) released from kaolinite dissolution at acidic pH, and finally approached the original value of the pure kaolinite. 31P NMR spectroscopy and ζ potential analyses revealed that IHP formed inner‐sphere surface complexes and aluminium phytate precipitated on kaolinite at low pH (2.5 and 4.0), whereas the formation of inner‐sphere surface complexes was the dominant sorption mechanism at pH ≥ 5.5. This study implies that various mechanisms, depending on ambient pH condition, can dominate the IHP sorption onto kaolinite, which impacts the mobility and bioavailability of phosphorus in highly weathered soils. Highlights IHP promotes the dissolution of kaolinite mainly through the formation of aluminium phytate complex. IHP sorption presents a sharp maximum at pH 4.0. IHP forms inner‐sphere complexes at the surface of kaolinite. Formation of aluminium phytate surface precipitates is favourable at relatively low pH.

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“…While orthophosphate may be the only P form in those extracts, it is also possible that other P forms were lost by precipitation with aluminum (Al) and iron (Fe) when the pH of soil extracts was increased, because these metals are found in much higher concentrations in soils than in animal manures. One approach that was recently used successfully to determine the effect of oxalate extraction on soil organic P forms was to treat acidic oxalate extracts with a cation exchange resin prior to pH adjustment, and to extract soil residues after oxalate extraction with NaOH-EDTA, comparing the changes in soil P forms to those from whole soil samples extracted in NaOH-EDTA and in the oxalate extracts [ 29 ]. Combining several spectroscopic techniques to analyze extracts can also confirm compound identifications [ 23 ].…”

Section: Introductionmentioning

confidence: 99%

Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

et al. 2018

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Phosphorus (P) can limit crop production in many soils, and soil testing is used to guide fertilizer recommendations. The Mehlich III (M3) soil test is widely used in North America, followed by colorimetric analysis for P, or by inductively coupled plasma-based spectrometry (ICP) for P and cations. However, differences have been observed in M3 P concentrations measured by these methods. Using 31P nuclear magnetic resonance (P-NMR) and mass spectrometry (MS), we characterized P forms in M3 extracts. In addition to the orthophosphate that would be detected during colorimetric analysis, several organic P forms were present in M3 extracts that would be unreactive colorimetrically but measured by ICP (molybdate unreactive P, MUP). Extraction of these P forms by M3 was confirmed by P-NMR and MS in NaOH-ethylenediaminetetraacetic acid extracts of whole soils and residues after M3 extraction. The most abundant P form in M3 extracts was myo-inositol hexaphosphate (myo-IHP, phytate), a compound that may not contribute to plant-available P if tightly sorbed in soil. Concentrations of myo-IHP and other organic P forms varied among soils, and even among treatment plots on the same soil. Extraction of myo-IHP in M3 appeared to be linked to cations, with substantially more myo-IHP extracted from soils fertilized with alum-treated poultry litter than untreated litter. These results suggest that ICP analysis may substantially over-estimate plant-available P in samples with high MUP concentrations, but there is no way at present to determine MUP concentrations without analysis by both colorimetry and ICP. This study also tested procedures that will improve future soil P-NMR studies, such as treatment of acid extracts, and demonstrated that techniques such as P-NMR and MS are complimentary, each yielding additional information that analysis by a single technique may not provide.

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Identification of inositol hexakisphosphate binding sites in soils by selective extraction and solution 31P NMR spectroscopy

Cited by 39 publications

References 49 publications

The C:N:P:S stoichiometry of soil organic matter

The C:N:P:S stoichiometry of soil organic matter

Adsorption and precipitation of myo‐inositol hexakisphosphate onto kaolinite

Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

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