³¹P-NMR characterization of phosphorus fractions in natural and fertilized forest soils

Abstract

-The amount, quality, and turnover of soil P is influenced by climate and changes in soil management. The objectives of this study were to evaluate the influence of edaphic properties, mean annual precipitation, and P-fertilization on soil organic P. 31 P-NMR spectroscopy was applied to investigate P forms of forest soils of the Central Western Spain. The concentrations of NaOHextractable inorganic-P were significantly higher in fertilized than in natural soils. Monoester-P was the dominant organic-P species in both natural and fertilized soils, representing between 19 and 54% of NaOH-extractable P. The highest concentrations of monoester-P were observed in the soil with higher content of Fe oxides. The high charge density of monoester-P allows rapid adsorption on soil minerals and extensive interaction with sesquioxides that protect inositols from degradation. Diester-P represented between 3 and 17% of alkali-extractable P, reflecting a relatively low microbial activity in the soils on schists with a high content of Al and Fe oxides.organic P / P-fertilization / forest soil / diester-monoester-P / 31 P-NMR Résumé -Caractérisation du phosphore et de ses fractions par la technique du NMR dans des sols forestiers fertilisés et nonfertilisés. La teneur, la qualité et le turnover du P du sol sont influencés par le climat et les changements dans la gestion du sol. L'objectif de cette étude a été d'évaluer l'influence des propriétés édaphiques, de la pluviométrie moyenne annuelle et de la fertilisation phosphatée sur le P organique du sol. La spectroscopie NMR a été appliquée pour rechercher les formes du P dans des sols forestiers du Centre Ouest de l'Espagne. La concentration en P inorganique extrait avec NaOH a été significativement plus haute dans le sol fertilisé que dans le sol naturel. Le monoester phosphorique (représentant entre 19 et 54 % du P extractable avec NaOH) est la forme dominante de P organique, aussi bien dans le sol naturel que dans le sol fertilisé. La plus haute concentration de monoester phosphorique a été observée dans le sol avec la plus haute teneur en oxydes ferriques. La haute densité de charge du monoester phosphorique permet sa rapide adsorption sur les composés mineraux du sol et son interation marquée avec les sesquioxydes, protégeant ainsi de la dégradation les inositols. Les diesters phosphoriques représentent entre 3 et 17 % du P extractable avec NaOH, montrant par là une relativement basse activité microbienne dans les sols sur schistes avec une haute teneur en oxydes aluminiques. P organique / fertilisation phosphorique / sols forestiers / esters phosphoriques / NMR du 31 P Ann. For. Sci. 58 (2001) [89][90][91][92][93][94][95][96][97][98] 89

Phosphorus speciation in temperate basaltic grassland soils by solution 31P NMR spectroscopy

“…Because of their large charge density, higher-order phosphate monoesters such as inositol phosphates are more strongly sorbed by metal oxides than orthophosphate (Turrion et al, 2001), which may protect them to a certain extent from phytase enzymes (Lung & Lim, 2006). Increased phosphate monoester concentrations in soils with greater PSC and greater dominance of phosphate monoesters in basaltic soils are consistent with this hypothesis.…”

Fósforo num Cambissolo cultivado com cana-de-açúcar por longo tempo: I - fracionamento seqüencial

“…A contribuição deste componente para o teor total de P é muito variável, dependendo de fatores, tais como: cobertura vegetal, condições climáticas e grau de evolução pedogenética (Walker & Adams, 1959;Turrión et al, 2001). A participação média do P orgânico em relação ao P total foi de 25 %, em superfície, e de 28 %, em subsuperfície, semelhante ao observado por Guerra et al (1996), que encontraram contribuição média de 27 % em amostras de 17 solos.…”

Phosphorus transformation in poultry litter and litter-treated Oxisol of Brazil assessed by 31P-NMR and wet chemical fractionation

“…At the end of the incubation period, the proportion of Po decreased by 41 % (decreased from 34 to 20 %) when incubated with soil and by 49 % (decreased from 41 to 21 %) when incubated without soil. The decrease in the Po mineralization rate in soil could possibly be due to a protection of organic phosphate compounds by adsorption on soil colloids (Cross & Schlesinger, 1995;Turrión et al, 2001;Conte et al, 2003), leading to the preferential preservation of some Po forms, especially orthophosphate monoesters (Koopmans et al, 2003). Pi increased linearly, irrespective of whether the RH litter was incubated with or without soil.…”

“…Diester phosphates, although found in small amounts, are reported to be chemically more labile than monoester P (Tate & Newman, 1982), with higher susceptibility to microbial or enzyme attack in the soil environment (Dai et al, 1996). Because the monoester is considered more stable and less accessible to plants than diester, the diester: monoester ratio is a measure of organic P lability (Chapuis-Lardy et al, 2001;Turrión et al, 2001). …”

“…Ci. Solo, 36:1516-1527 low charge density reduces the energy of interaction with soil colloids and they become more easily accessible to decomposers (Turrión et al, 2001). In semi-arid Northern Tanzania, clearing and continuous low input agriculture reduced both organic and inorganic P in the soil.…”