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Christensen S, Rousk K. Global N 2O emissions from our planet: Which fluxes are affected by man, and can we reduce these? iScience 2024; 27:109042. [PMID: 38333714 PMCID: PMC10850745 DOI: 10.1016/j.isci.2024.109042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2024] Open
Abstract
In some places, N2O emissions have doubled during the last 2-3 decades. Therefore, it is crucial to identify N2O emission hotspots from terrestrial and aquatic systems. Large variation in N2O emissions occur in managed as well as in natural areas. Natural unmanaged tropical and subtropical wet forests are important N2O sources globally. Emission hotspots, often coupled to human activities, vary across climate zones, whereas N2O emissions are most often a few kg N ha-1 year-1 from arable soils, drained organic soils in the boreal and temperate zones often release 20-30 kg N ha-1 year-1. Similar high N2O emissions occur from some tropical crops like tea, palm oil and bamboo. This strong link between increased N2O emissions and human activities highlight the potential to mitigate large emissions. In contrast, water where oxic and anoxic conditions meet are N2O emission hotspots as well, but not possible to reduce.
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Affiliation(s)
- Søren Christensen
- Copenhagen University, Department of Biology, VOLT, Center for Volatile Interactions, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Kathrin Rousk
- Copenhagen University, Department of Biology, VOLT, Center for Volatile Interactions, Universitetsparken 15, 2100 Copenhagen, Denmark
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Yao Z, Guo H, Wang Y, Zhan Y, Zhang T, Wang R, Zheng X, Butterbach-Bahl K. A global meta-analysis of yield-scaled N 2 O emissions and its mitigation efforts for maize, wheat, and rice. GLOBAL CHANGE BIOLOGY 2024; 30:e17177. [PMID: 38348630 DOI: 10.1111/gcb.17177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/09/2024] [Accepted: 01/22/2024] [Indexed: 02/15/2024]
Abstract
Maintaining or even increasing crop yields while reducing nitrous oxide (N2 O) emissions is necessary to reconcile food security and climate change, while the metric of yield-scaled N2 O emission (i.e., N2 O emissions per unit of crop yield) is at present poorly understood. Here we conducted a global meta-analysis with more than 6000 observations to explore the variation patterns and controlling factors of yield-scaled N2 O emissions for maize, wheat and rice and associated potential mitigation options. Our results showed that the average yield-scaled N2 O emissions across all available data followed the order wheat (322 g N Mg-1 , with the 95% confidence interval [CI]: 301-346) > maize (211 g N Mg-1 , CI: 198-225) > rice (153 g N Mg-1 , CI: 144-163). Yield-scaled N2 O emissions for individual crops were generally higher in tropical or subtropical zones than in temperate zones, and also showed a trend towards lower intensities from low to high latitudes. This global variation was better explained by climatic and edaphic factors than by N fertilizer management, while their combined effect predicted more than 70% of the variance. Furthermore, our analysis showed a significant decrease in yield-scaled N2 O emissions with increasing N use efficiency or in N2 O emissions for production systems with cereal yields >10 Mg ha-1 (maize), 6.6 Mg ha-1 (wheat) or 6.8 Mg ha-1 (rice), respectively. This highlights that N use efficiency indicators can be used as valuable proxies for reconciling trade-offs between crop production and N2 O mitigation. For all three major staple crops, reducing N fertilization by up to 30%, optimizing the timing and placement of fertilizer application or using enhanced-efficiency N fertilizers significantly reduced yield-scaled N2 O emissions at similar or even higher cereal yields. Our data-driven assessment provides some key guidance for developing effective and targeted mitigation and adaptation strategies for the sustainable intensification of cereal production.
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Affiliation(s)
- Zhisheng Yao
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Haojie Guo
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Yan Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Yang Zhan
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Tianli Zhang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Rui Wang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
| | - Xunhua Zheng
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- College of Earth and Planetary Science, University of Chinese Academy of Sciences, Beijing, P.R. China
| | - Klaus Butterbach-Bahl
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, P.R. China
- Institute for Meteorology and Climate Research, Atmospheric Environmental Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany
- Pioneer Center Land-CRAFT, Department of Agroecology, Aarhus University, Aarhus C, Denmark
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Iboko MP, Dossou-Yovo ER, Obalum SE, Oraegbunam CJ, Diedhiou S, Brümmer C, Témé N. Paddy rice yield and greenhouse gas emissions: Any trade-off due to co-application of biochar and nitrogen fertilizer? A systematic review. Heliyon 2023; 9:e22132. [PMID: 38045115 PMCID: PMC10692810 DOI: 10.1016/j.heliyon.2023.e22132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/27/2023] [Accepted: 11/05/2023] [Indexed: 12/05/2023] Open
Abstract
Combined application of biochar and nitrogen (N) fertilizer could offer opportunities to increase rice yield and reduce methane emissions from paddy fields. However, this strategy may increase nitrous oxide (N2O) emissions, hence its interactive effects on GHG emissions, global warming potential (GWP) and GHG intensity (GHGI) remained poorly understood. We conducted a systematic review to i) evaluate the overall effects of combined application of biochar and N fertilizer rates on GHGs emissions, GWP, rice yield, and GHGI, ii) determine the quantities of biochar and N-fertilizer application that increase rice yield and reduce GHGs emissions and GHGI, and iii) examine the effects of biochar and different types of nitrogen fertilizers on rice yield, GHGs, GWP, and GHGI using data from 45 research articles and 183 paired observations. The extracted data were grouped based on biochar and N rates used by researchers as well as N fertiliser types. Accordingly, biochar rates were grouped into low (≤9 tons/ha), medium (>9 and ≤ 20 ton/ha) and high (>20 tons/ha), while N rates were grouped into three categories: low (≤140 kg N/ha), medium (>140 and ≤ 240 kg N/ha), and high (>240 kg N/ha). For fertiliser types, N rates were grouped as: low (≤150 kg N/ha), medium (>150 and ≤250 kg N/ha), and high (>250 kg N/ha) and N types into: urea, NPK, NPK plus urea (NPK_urea) and NPK plus (NH4)2SO4 (NPK_(NH4)2SO4). Results showed that biochar and N fertiliser significantly affected GHGs emissions, GWP, GHGI and rice yield. Compared to control (i.e., sole N application), co-application of high biochar and medium N rates significantly decreased CH4 emission (82 %) while low biochar with low N rates enhanced CH4 emission (114 %). In contrast, high biochar combined with low N decreased N2O emission by 91 % whereas medium biochar and high N rates resulted in 82 % increase in N2O emission relative to control. The highest GWP and GHGI were observed under co-application of medium biochar and low N rates. Highest rice yield was observed under low biochar rate and high N rate. Regardless of N fertiliser type and biochar rates, increasing N rates increased rice yield and N2O emissions. The highest GWP and GHGI were recorded under sole NPK application. Combination of low biochar and medium N produced low GHGs emissions, high grain yield, and the lowest GHGI, and could be recommended to smallholder farmers to increase rice yield and reduce greenhouse gas emissions from paddy rice field. Further studies should be conducted to evaluate the effects of biochar properties on soil characteristics and greenhouse gas emissions.
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Affiliation(s)
- Maduabuchi P. Iboko
- Graduate Research Program, Climate Change and Agriculture, Université des Sciences, des Techniques et des Technologies de Bamako (USTTB), Mali
- Graduate Research Program, Climate Change and Agriculture, Institut Polytechnique Rural de Formation et de Recherche Appliquée, Katibougou, Mali
- School of Agriculture, University of Cape Coast, Cape Coast, Ghana
| | | | - Sunday E. Obalum
- Department of Soil Science, University of Nigeria, Nsukka, 410001, Nigeria
| | - Chidozie J. Oraegbunam
- Global Station for Food, Land & Water Resources, Research Faculty of Agriculture, Hokkaido University, Kita 9 Nishi 9 Kita-Ku, Sapporo, Hokkaido, 060-8589, Japan
| | - Siméon Diedhiou
- Graduate Research Program, Climate Change and Agriculture, Université des Sciences, des Techniques et des Technologies de Bamako (USTTB), Mali
- Graduate Research Program, Climate Change and Agriculture, Institut Polytechnique Rural de Formation et de Recherche Appliquée, Katibougou, Mali
- School of Agriculture, University of Cape Coast, Cape Coast, Ghana
| | - Christian Brümmer
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, 38116, Braunschweig, Germany
| | - Niaba Témé
- Labo Biotechnologie, Institute D'Economie Rurale, Sotuba, Mali
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