Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux
IntroductionUnderstanding how nutrient inputs affect nitrogen (N) transformations and storage is vital for developing sustainable agroecosystems. Organic N inputs, such as crop residues (e.g., cover crop biomass and stover) and animal manures, can accelerate N cycling by increasing mineralization an...
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Frontiers Media S.A.
2025-02-01
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| Series: | Frontiers in Agronomy |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fagro.2025.1472749/full |
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| author | Lauren C. Breza A. Stuart Grandy A. Stuart Grandy |
| author_facet | Lauren C. Breza A. Stuart Grandy A. Stuart Grandy |
| author_sort | Lauren C. Breza |
| collection | DOAJ |
| description | IntroductionUnderstanding how nutrient inputs affect nitrogen (N) transformations and storage is vital for developing sustainable agroecosystems. Organic N inputs, such as crop residues (e.g., cover crop biomass and stover) and animal manures, can accelerate N cycling by increasing mineralization and immobilization rates to provide crops with more opportunities to intercept N as it moves through bioavailable pools. We aimed to understand how organic and synthetic soil amendments inhibit or promote N mineralization, immobilization, and nitrification rates.MethodsWe conducted a meta-analysis of peer-reviewed studies to assess N transformation rates in agroecosystems. Specifically, we targeted studies employing 15N pool dilution methods to quantify N mineralization, immobilization, and nitrification rates in response to organic and synthetic soil amendments.Results and discussionOur findings indicate that adding synthetic, manure, and crop derived residues as soil amendments increased mineralization by 60%, 135%, and 214%, respectively, relative to the unamended controls. While manure and residue produced similar mineralization rates, residue amendments induced significantly higher immobilization rates than synthetic and manure amendments – a sevenfold and fourfold increase, respectively. Furthermore, only residue N amendments enhanced the ammonium (NH4+) pool size, while synthetic and manure amendments resulted in no change in NH4+ pool size. These results suggest that residue amendments encourage tighter coupling of the carbon (C) and N cycles compared to manure or synthetic amendments by delivering C rich substrates (e.g., C:N ratio >20:1) to soil microbes. This tighter coupling with residue amendments leads to faster mineralization-immobilization processes and larger NH4+ pools than those observed with manure or synthetic amendments. As such, residue amendments encourage soil N recycling between inorganic and organic forms, which is crucial to supporting crop N needs throughout the growing season while minimizing N losses. |
| format | Article |
| id | doaj-art-a1e0a7c7bb1c41cd8905abef10eb386a |
| institution | Kabale University |
| issn | 2673-3218 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Agronomy |
| spelling | doaj-art-a1e0a7c7bb1c41cd8905abef10eb386a2025-02-10T11:32:45ZengFrontiers Media S.A.Frontiers in Agronomy2673-32182025-02-01710.3389/fagro.2025.14727491472749Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen fluxLauren C. Breza0A. Stuart Grandy1A. Stuart Grandy2Forage Seed and Cereal Research Unit, Agricultural Research Service (USDA), Corvallis, OR, United StatesDepartment of Natural Resources and Environment, University of New Hampshire, Durham, NH, United StatesCenter of Soil Biogeochemistry and Microbial Ecology (Soil BioME), University of New Hampshire, Durham, NH, United StatesIntroductionUnderstanding how nutrient inputs affect nitrogen (N) transformations and storage is vital for developing sustainable agroecosystems. Organic N inputs, such as crop residues (e.g., cover crop biomass and stover) and animal manures, can accelerate N cycling by increasing mineralization and immobilization rates to provide crops with more opportunities to intercept N as it moves through bioavailable pools. We aimed to understand how organic and synthetic soil amendments inhibit or promote N mineralization, immobilization, and nitrification rates.MethodsWe conducted a meta-analysis of peer-reviewed studies to assess N transformation rates in agroecosystems. Specifically, we targeted studies employing 15N pool dilution methods to quantify N mineralization, immobilization, and nitrification rates in response to organic and synthetic soil amendments.Results and discussionOur findings indicate that adding synthetic, manure, and crop derived residues as soil amendments increased mineralization by 60%, 135%, and 214%, respectively, relative to the unamended controls. While manure and residue produced similar mineralization rates, residue amendments induced significantly higher immobilization rates than synthetic and manure amendments – a sevenfold and fourfold increase, respectively. Furthermore, only residue N amendments enhanced the ammonium (NH4+) pool size, while synthetic and manure amendments resulted in no change in NH4+ pool size. These results suggest that residue amendments encourage tighter coupling of the carbon (C) and N cycles compared to manure or synthetic amendments by delivering C rich substrates (e.g., C:N ratio >20:1) to soil microbes. This tighter coupling with residue amendments leads to faster mineralization-immobilization processes and larger NH4+ pools than those observed with manure or synthetic amendments. As such, residue amendments encourage soil N recycling between inorganic and organic forms, which is crucial to supporting crop N needs throughout the growing season while minimizing N losses.https://www.frontiersin.org/articles/10.3389/fagro.2025.1472749/fullgross nitrogen transformationsgross nitrogen mineralizationgross nitrogen immobilization15Nisotope pool dilutionorganic amendment |
| spellingShingle | Lauren C. Breza A. Stuart Grandy A. Stuart Grandy Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux Frontiers in Agronomy gross nitrogen transformations gross nitrogen mineralization gross nitrogen immobilization 15N isotope pool dilution organic amendment |
| title | Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux |
| title_full | Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux |
| title_fullStr | Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux |
| title_full_unstemmed | Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux |
| title_short | Organic amendments tighten nitrogen cycling in agricultural soils: a meta-analysis on gross nitrogen flux |
| title_sort | organic amendments tighten nitrogen cycling in agricultural soils a meta analysis on gross nitrogen flux |
| topic | gross nitrogen transformations gross nitrogen mineralization gross nitrogen immobilization 15N isotope pool dilution organic amendment |
| url | https://www.frontiersin.org/articles/10.3389/fagro.2025.1472749/full |
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