Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses
Livestock manure contributes to global warming due to greenhouse gas (GHG) emissions, especially nitrous oxide (N2O) and methane (CH4). In the arid and semi-arid lands of Sub-Saharan Africa (SSA), extensive pastoral grazing systems are common, with cattle grazing in the savanna during the day and ke...
| Autores principales: | , , , , , , , , , , , |
|---|---|
| Formato: | Journal Article |
| Lenguaje: | Inglés |
| Publicado: |
Elsevier
2024
|
| Materias: | |
| Acceso en línea: | https://hdl.handle.net/10568/149305 |
| _version_ | 1855542559675252736 |
|---|---|
| author | Xiantao Fang Harris, S.J. Leitner, Sonja Butterbach-Bahl, Klaus Conz, R.F. Merbold, Lutz Dannenmann, M. Oyugi, A. Shuwei Liu Jianwen Zou Six, Johan Barthel, M. |
| author_browse | Barthel, M. Butterbach-Bahl, Klaus Conz, R.F. Dannenmann, M. Harris, S.J. Jianwen Zou Leitner, Sonja Merbold, Lutz Oyugi, A. Shuwei Liu Six, Johan Xiantao Fang |
| author_facet | Xiantao Fang Harris, S.J. Leitner, Sonja Butterbach-Bahl, Klaus Conz, R.F. Merbold, Lutz Dannenmann, M. Oyugi, A. Shuwei Liu Jianwen Zou Six, Johan Barthel, M. |
| author_sort | Xiantao Fang |
| collection | Repository of Agricultural Research Outputs (CGSpace) |
| description | Livestock manure contributes to global warming due to greenhouse gas (GHG) emissions, especially nitrous oxide (N2O) and methane (CH4). In the arid and semi-arid lands of Sub-Saharan Africa (SSA), extensive pastoral grazing systems are common, with cattle grazing in the savanna during the day and kept in enclosures (called bomas in Kenya) during the night. Manure is usually not removed from bomas but left to accumulate, leading to excessive local nitrogen loads, making these bomas an overlooked N2O emission hotspot in SSA that is currently not accounted for in national and regional GHG budgets. Here, we present the first in-situ isotope measurements of N2O fluxes from 37 cattle bomas along an age gradient ranging from 0 to 5 years after boma abandonment in Kenya along with functional gene analysis of soil and manure samples. The isotopic composition of the emitted N2O from bomas suggests that on average 91 ± 8% N2O was produced via bacterial denitrification and/or nitrifier denitrification, with little variation across boma age class. We also found high levels of N2O reduction to N2 across all sample sites (81 ± 9%), indicating high levels of N2O consumption. The abundances of denitrification-related genes (nirK and narG) were significantly higher than those of nitrification-related genes (amoA: AOA and AOB) in the cattle manure samples taken from the bomas, corroborating N2O emissions largely being attributed to denitrification. Significant abundance of the reduction-related gene (nosZ) also corroborated the high potential for microbial N2O reduction in bomas. Thus, by combining dual-isotope and functional gene analysis, we were able to identify source processes that govern N2O emissions from these systems. More generally, making use of the manure by spreading it in the vicinity of the bomas or on dedicated forage plots could provide a win-win by enhancing savanna productivity while simultaneously mitigating GHG emissions. |
| format | Journal Article |
| id | CGSpace149305 |
| institution | CGIAR Consortium |
| language | Inglés |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Elsevier |
| publisherStr | Elsevier |
| record_format | dspace |
| spelling | CGSpace1493052025-10-26T12:51:11Z Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses Xiantao Fang Harris, S.J. Leitner, Sonja Butterbach-Bahl, Klaus Conz, R.F. Merbold, Lutz Dannenmann, M. Oyugi, A. Shuwei Liu Jianwen Zou Six, Johan Barthel, M. gas emissions emission livestock manure forage Livestock manure contributes to global warming due to greenhouse gas (GHG) emissions, especially nitrous oxide (N2O) and methane (CH4). In the arid and semi-arid lands of Sub-Saharan Africa (SSA), extensive pastoral grazing systems are common, with cattle grazing in the savanna during the day and kept in enclosures (called bomas in Kenya) during the night. Manure is usually not removed from bomas but left to accumulate, leading to excessive local nitrogen loads, making these bomas an overlooked N2O emission hotspot in SSA that is currently not accounted for in national and regional GHG budgets. Here, we present the first in-situ isotope measurements of N2O fluxes from 37 cattle bomas along an age gradient ranging from 0 to 5 years after boma abandonment in Kenya along with functional gene analysis of soil and manure samples. The isotopic composition of the emitted N2O from bomas suggests that on average 91 ± 8% N2O was produced via bacterial denitrification and/or nitrifier denitrification, with little variation across boma age class. We also found high levels of N2O reduction to N2 across all sample sites (81 ± 9%), indicating high levels of N2O consumption. The abundances of denitrification-related genes (nirK and narG) were significantly higher than those of nitrification-related genes (amoA: AOA and AOB) in the cattle manure samples taken from the bomas, corroborating N2O emissions largely being attributed to denitrification. Significant abundance of the reduction-related gene (nosZ) also corroborated the high potential for microbial N2O reduction in bomas. Thus, by combining dual-isotope and functional gene analysis, we were able to identify source processes that govern N2O emissions from these systems. More generally, making use of the manure by spreading it in the vicinity of the bomas or on dedicated forage plots could provide a win-win by enhancing savanna productivity while simultaneously mitigating GHG emissions. 2024-09 2024-07-30T12:12:32Z 2024-07-30T12:12:32Z Journal Article https://hdl.handle.net/10568/149305 en Open Access Elsevier Xiantao Fang, Harris, S.J., Leitner, S.M., Butterbach-Bahl, K., Conz, R.F., Merbold, L., Dannenmann, M., Oyugi, A., Shuwei Liu, Jianwen Zou, Six, J. and Barthel, M. 2024. Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses. Soil Biology and Biochemistry 196:109505. |
| spellingShingle | gas emissions emission livestock manure forage Xiantao Fang Harris, S.J. Leitner, Sonja Butterbach-Bahl, Klaus Conz, R.F. Merbold, Lutz Dannenmann, M. Oyugi, A. Shuwei Liu Jianwen Zou Six, Johan Barthel, M. Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses |
| title | Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses |
| title_full | Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses |
| title_fullStr | Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses |
| title_full_unstemmed | Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses |
| title_short | Mechanisms behind high N2O emissions from livestock enclosures in Kenya revealed by dual-isotope and functional gene analyses |
| title_sort | mechanisms behind high n2o emissions from livestock enclosures in kenya revealed by dual isotope and functional gene analyses |
| topic | gas emissions emission livestock manure forage |
| url | https://hdl.handle.net/10568/149305 |
| work_keys_str_mv | AT xiantaofang mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT harrissj mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT leitnersonja mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT butterbachbahlklaus mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT conzrf mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT merboldlutz mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT dannenmannm mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT oyugia mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT shuweiliu mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT jianwenzou mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT sixjohan mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses AT barthelm mechanismsbehindhighn2oemissionsfromlivestockenclosuresinkenyarevealedbydualisotopeandfunctionalgeneanalyses |