In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability
While there are estimates of the abiotic processes contribution to soil phosphorus (P) availability, less is known about the contribution of biological processes. Two main enzymatic processes involved in soil P cycling are known to alter the oxygen isotopic composition of phosphate (δ18O-P), each in...
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Frontiers Media S.A.
2020-09-01
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| Series: | Frontiers in Environmental Science |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fenvs.2020.564778/full |
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| author | Chiara Pistocchi Chiara Pistocchi Éva Mészáros Éva Mészáros Emmanuel Frossard E. K. Bünemann E. K. Bünemann Federica Tamburini |
| author_facet | Chiara Pistocchi Chiara Pistocchi Éva Mészáros Éva Mészáros Emmanuel Frossard E. K. Bünemann E. K. Bünemann Federica Tamburini |
| author_sort | Chiara Pistocchi |
| collection | DOAJ |
| description | While there are estimates of the abiotic processes contribution to soil phosphorus (P) availability, less is known about the contribution of biological processes. Two main enzymatic processes involved in soil P cycling are known to alter the oxygen isotopic composition of phosphate (δ18O-P), each in a different way, through the cleavage of the P–O bond: the intracellular P turnover and the organic P hydrolysis. The former induces isotopic equilibration between phosphate and water and is considered the major process affecting soil available P via microbial P release. The latter induces depleted δ18O-P in the phosphate released from the mineralization of organic P. We studied P dynamics in organic horizons of two contrasting soils (low- and high-P availability) from temperate beech forests. We labeled the soil with 18O-enriched water and followed changes in the δ18O-P of different soil P pools in the presence or absence of added leaf litter during 3 months of incubation. δ18O-P values of almost all P pools progressively increased indicating oxygen incorporation from the enriched soil water into phosphate via the above-mentioned enzymatic processes. δ18O-P of available P increased more in the P-rich soil than in the P-poor soil and approached the isotopic equilibrium between phosphate and water, revealing the impact of microbial P release into the available P pool. However, in the P-poor soil, the available P brought the isotopic signature induced by phosphatase enzymes, indicating that it was mostly originated from the hydrolysis of organic P. Therefore, under P-limiting conditions, the isotopic effect of organic P hydrolysis can outweigh the isotopic equilibrium effect. Finally, two independent isotopic approaches with 33P and δ18O-P provided very similar estimates of P exchanged between the available P and other inorganic soil pools. This suggests that δ18O-P can be successfully used to trace P fluxes, provided that the underlying processes do not break the P–O bonds of the phosphate molecule. |
| first_indexed | 2024-12-20T21:17:52Z |
| format | Article |
| id | doaj.art-ecc8d0e91d6b4c0fb8f37a0b77901762 |
| institution | Directory Open Access Journal |
| issn | 2296-665X |
| language | English |
| last_indexed | 2024-12-20T21:17:52Z |
| publishDate | 2020-09-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Environmental Science |
| spelling | doaj.art-ecc8d0e91d6b4c0fb8f37a0b779017622022-12-21T19:26:23ZengFrontiers Media S.A.Frontiers in Environmental Science2296-665X2020-09-01810.3389/fenvs.2020.564778564778In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus AvailabilityChiara Pistocchi0Chiara Pistocchi1Éva Mészáros2Éva Mészáros3Emmanuel Frossard4E. K. Bünemann5E. K. Bünemann6Federica Tamburini7Institute of Agricultural Science, ETH Zürich, Zurich, SwitzerlandEco&Sols, Montpellier SupAgro, Univ Montpellier, CIRAD, INRAE, IRD, Montpellier, FranceInstitute of Agricultural Science, ETH Zürich, Zurich, SwitzerlandDepartment of Biosystems Science and Engineering, ETH Zürich, Basel, SwitzerlandInstitute of Agricultural Science, ETH Zürich, Zurich, SwitzerlandInstitute of Agricultural Science, ETH Zürich, Zurich, SwitzerlandDepartment of Soil Sciences, Research Institute of Organic Agriculture FiBL, Frick, SwitzerlandInstitute of Agricultural Science, ETH Zürich, Zurich, SwitzerlandWhile there are estimates of the abiotic processes contribution to soil phosphorus (P) availability, less is known about the contribution of biological processes. Two main enzymatic processes involved in soil P cycling are known to alter the oxygen isotopic composition of phosphate (δ18O-P), each in a different way, through the cleavage of the P–O bond: the intracellular P turnover and the organic P hydrolysis. The former induces isotopic equilibration between phosphate and water and is considered the major process affecting soil available P via microbial P release. The latter induces depleted δ18O-P in the phosphate released from the mineralization of organic P. We studied P dynamics in organic horizons of two contrasting soils (low- and high-P availability) from temperate beech forests. We labeled the soil with 18O-enriched water and followed changes in the δ18O-P of different soil P pools in the presence or absence of added leaf litter during 3 months of incubation. δ18O-P values of almost all P pools progressively increased indicating oxygen incorporation from the enriched soil water into phosphate via the above-mentioned enzymatic processes. δ18O-P of available P increased more in the P-rich soil than in the P-poor soil and approached the isotopic equilibrium between phosphate and water, revealing the impact of microbial P release into the available P pool. However, in the P-poor soil, the available P brought the isotopic signature induced by phosphatase enzymes, indicating that it was mostly originated from the hydrolysis of organic P. Therefore, under P-limiting conditions, the isotopic effect of organic P hydrolysis can outweigh the isotopic equilibrium effect. Finally, two independent isotopic approaches with 33P and δ18O-P provided very similar estimates of P exchanged between the available P and other inorganic soil pools. This suggests that δ18O-P can be successfully used to trace P fluxes, provided that the underlying processes do not break the P–O bonds of the phosphate molecule.https://www.frontiersin.org/article/10.3389/fenvs.2020.564778/fullsoilisotopic labelingphosphatasemicrobial phosphorusmineralization |
| spellingShingle | Chiara Pistocchi Chiara Pistocchi Éva Mészáros Éva Mészáros Emmanuel Frossard E. K. Bünemann E. K. Bünemann Federica Tamburini In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability Frontiers in Environmental Science soil isotopic labeling phosphatase microbial phosphorus mineralization |
| title | In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability |
| title_full | In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability |
| title_fullStr | In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability |
| title_full_unstemmed | In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability |
| title_short | In or Out of Equilibrium? How Microbial Activity Controls the Oxygen Isotopic Composition of Phosphate in Forest Organic Horizons With Low and High Phosphorus Availability |
| title_sort | in or out of equilibrium how microbial activity controls the oxygen isotopic composition of phosphate in forest organic horizons with low and high phosphorus availability |
| topic | soil isotopic labeling phosphatase microbial phosphorus mineralization |
| url | https://www.frontiersin.org/article/10.3389/fenvs.2020.564778/full |
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