Microbial Immobilization Shapes the Non-Linear Response of Allochthonous Nitrogen Retention to Grassland Acidification Within Soil Aggregates
© 2025 John Wiley & Sons Ltd.
| Publié dans: | Global change biology. - 1999. - 31(2025), 5 vom: 07. Mai, Seite e70229 |
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| Auteur principal: | |
| Autres auteurs: | , , , , , , |
| Format: | Article en ligne |
| Langue: | English |
| Publié: |
2025
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| Accès à la collection: | Global change biology |
| Sujets: | Journal Article grassland microbial necromass nitrogen cycling soil aggregate sulfur deposition Soil Nitrogen N762921K75 |
| Résumé: | © 2025 John Wiley & Sons Ltd. Soil nitrogen (N) retention plays a crucial role in determining the ecosystem capacity to buffer anthropogenic N inputs and provides a sustainable N supply. However, the effect of acidification, driven by atmospheric deposition of N and sulfur (S), on the retention and fate of allochthonous N across soil aggregate size classes remains poorly understood. We utilized a soil-acidification gradient induced by 0-50 g S m-2 year-1 addition to investigate 15N recovery in soil N pools within aggregates 21 days after labeling in a Eurasian meadow. Macroaggregates showed higher 15N recovery in microbial biomass, amino acids, amino sugars, and therefore total N (TN), as well as greater sensitivity of the former two fractions to acidification compared to microaggregates. This was accompanied by higher N hydrolases and net N mineralization in macroaggregates, supporting the aggregate hierarchical theory. Under moderate acidification (pH decrease from 7 to 6), 15N retention in hydrolyzable ammonium, amino sugars, non-hydrolyzable N, and TN decreased, likely due to lower microbial immobilization and entombing of allochthonous N. Conversely, severe acidification (pH decrease below 6) enhanced 15N retention in these N fractions through stabilization of microbial necromass, revealing a non-linear relationship between acidification and 15N retention. Concentrations of autochthonous organic N fractions remained unchanged after five-year acidification. These findings underscore the mediating role of soil microbes across aggregates in allochthonous 15N retention among N fractions with contrasting bioavailability under acidification |
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| Description: | Date Completed 07.05.2025 Date Revised 07.05.2025 published: Print Citation Status MEDLINE |
| ISSN: | 1365-2486 |
| DOI: | 10.1111/gcb.70229 |