Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans
Soil microorganisms have long been recognized as primary producers of biogenic N<sub>2</sub>O in terrestrial ecosystems. Terrestrial plants can contribute to N<sub>2</sub>O emissions by transporting N<sub>2</sub>O produced in soils, and there is also evidence that...
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2024-12-01
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| author | Zongwei Xia Guanxiong Chen Kewei Yu Hui Xu Xiuling Yu |
| author_facet | Zongwei Xia Guanxiong Chen Kewei Yu Hui Xu Xiuling Yu |
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| description | Soil microorganisms have long been recognized as primary producers of biogenic N<sub>2</sub>O in terrestrial ecosystems. Terrestrial plants can contribute to N<sub>2</sub>O emissions by transporting N<sub>2</sub>O produced in soils, and there is also evidence that plants may serve as direct producers of N<sub>2</sub>O. However, to date, direct evidence for N<sub>2</sub>O production by plants remains limited. To exclude N<sub>2</sub>O emissions resulting from soil-to-plant transport, this study conducted incubation experiments using cut soybean branches and leaves (cSBF) and intact soil cores under an N<sub>2</sub>O-free air background. The natural isotopic signatures (δ<sup>15</sup>N and δ<sup>18</sup>O) and fluxes of N<sub>2</sub>O produced by cSBF and soil were compared across different soybean growth stages over two growing seasons. The observed δ<sup>15</sup>N and δ<sup>18</sup>O values of N<sub>2</sub>O from soil ranged from −26.7‰ to −5.3‰ and −24.1‰ to 22.8‰, respectively. In contrast, the values for N<sub>2</sub>O produced from cSBF ranged from −4.7‰ to 33.1‰ and from 23.7‰ to 88.8‰, respectively. Notably, N<sub>2</sub>O emitted from plants exhibited significantly higher δ<sup>15</sup>N and δ<sup>18</sup>O values than soil-derived N<sub>2</sub>O (<i>p</i> < 0.05). These findings indicate that the pathways and mechanisms of N<sub>2</sub>O production and emission in soybean plants differ from those mediated by soil microorganisms and nitrogen transport processes. Additionally, a significantly higher amount of N<sub>2</sub>O emission was observed during early growth stages compared to late growth stages (<i>p</i> < 0.01), suggesting that plant N<sub>2</sub>O production may be associated with elevated water content and oxygen-limited conditions within plant cells. In addition to the N<sub>2</sub>O uptake by plants observed in some literature, the positive relationship between δ<sup>15</sup>N values and N<sub>2</sub>O fluxes suggests that N<sub>2</sub>O could be consumed in plant cells (<i>p</i> < 0.01), with a high consumption rate often associated with a high production rate. The results of this study provide compelling evidence that plants may represent an overlooked source of N<sub>2</sub>O in terrestrial ecosystems. |
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| spelling | doaj-art-02e83c23ffdf4f0b98423760adae4c832025-08-20T02:50:56ZengMDPI AGAgronomy2073-43952024-12-011412287510.3390/agronomy14122875Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of SoybeansZongwei Xia0Guanxiong Chen1Kewei Yu2Hui Xu3Xiuling Yu4Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, College of Resources and Environment, Linyi University, Linyi 276000, ChinaInstitute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, ChinaDepartment of Biological and Environmental Sciences, Troy University, Troy, AL 36082, USAInstitute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, ChinaShandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, College of Resources and Environment, Linyi University, Linyi 276000, ChinaSoil microorganisms have long been recognized as primary producers of biogenic N<sub>2</sub>O in terrestrial ecosystems. Terrestrial plants can contribute to N<sub>2</sub>O emissions by transporting N<sub>2</sub>O produced in soils, and there is also evidence that plants may serve as direct producers of N<sub>2</sub>O. However, to date, direct evidence for N<sub>2</sub>O production by plants remains limited. To exclude N<sub>2</sub>O emissions resulting from soil-to-plant transport, this study conducted incubation experiments using cut soybean branches and leaves (cSBF) and intact soil cores under an N<sub>2</sub>O-free air background. The natural isotopic signatures (δ<sup>15</sup>N and δ<sup>18</sup>O) and fluxes of N<sub>2</sub>O produced by cSBF and soil were compared across different soybean growth stages over two growing seasons. The observed δ<sup>15</sup>N and δ<sup>18</sup>O values of N<sub>2</sub>O from soil ranged from −26.7‰ to −5.3‰ and −24.1‰ to 22.8‰, respectively. In contrast, the values for N<sub>2</sub>O produced from cSBF ranged from −4.7‰ to 33.1‰ and from 23.7‰ to 88.8‰, respectively. Notably, N<sub>2</sub>O emitted from plants exhibited significantly higher δ<sup>15</sup>N and δ<sup>18</sup>O values than soil-derived N<sub>2</sub>O (<i>p</i> < 0.05). These findings indicate that the pathways and mechanisms of N<sub>2</sub>O production and emission in soybean plants differ from those mediated by soil microorganisms and nitrogen transport processes. Additionally, a significantly higher amount of N<sub>2</sub>O emission was observed during early growth stages compared to late growth stages (<i>p</i> < 0.01), suggesting that plant N<sub>2</sub>O production may be associated with elevated water content and oxygen-limited conditions within plant cells. In addition to the N<sub>2</sub>O uptake by plants observed in some literature, the positive relationship between δ<sup>15</sup>N values and N<sub>2</sub>O fluxes suggests that N<sub>2</sub>O could be consumed in plant cells (<i>p</i> < 0.01), with a high consumption rate often associated with a high production rate. The results of this study provide compelling evidence that plants may represent an overlooked source of N<sub>2</sub>O in terrestrial ecosystems.https://www.mdpi.com/2073-4395/14/12/2875N<sub>2</sub>Osoybean plantsoilδ<sup>15</sup>Nδ<sup>18</sup>Oisotopic fractionation |
| spellingShingle | Zongwei Xia Guanxiong Chen Kewei Yu Hui Xu Xiuling Yu Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans Agronomy N<sub>2</sub>O soybean plant soil δ<sup>15</sup>N δ<sup>18</sup>O isotopic fractionation |
| title | Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans |
| title_full | Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans |
| title_fullStr | Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans |
| title_full_unstemmed | Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans |
| title_short | Isotopic Signatures and Fluxes of N<sub>2</sub>O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans |
| title_sort | isotopic signatures and fluxes of n sub 2 sub o emitted from soybean plants and soil during the main growth period of soybeans |
| topic | N<sub>2</sub>O soybean plant soil δ<sup>15</sup>N δ<sup>18</sup>O isotopic fractionation |
| url | https://www.mdpi.com/2073-4395/14/12/2875 |
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