| 中国旱作农田一氧化氮排放及减排:Meta分析 |
| 摘要点击 1484 全文点击 391 投稿时间：2022-02-09 修订日期：2022-03-21 |
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| 中文关键词 一氧化氮(NO) 排放系数 旱作农田 减排措施 整合分析 |
| 英文关键词 nitric oxide (NO) emission factor upland cropping systems mitigation strategy Meta-analysis |
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| 中文摘要 |
| 农田是大气污染物一氧化氮（NO）的主要排放源之一.与水稻田相比，旱作农田NO排放量和排放系数高，但其异质性及影响因素尚不明确.目前，我国农田NO排放和减排的研究以原位观测为主，缺乏系统的整合（Meta）分析.通过收集文献数据，定量分析玉米-冬小麦、水稻-冬小麦旱地阶段、蔬菜、茶园和果园等旱作体系NO排放量和排放系数的异质性及主要影响因素；定量评价减量施氮、有机肥替代化肥、配施新型增效氮肥和施用生物质炭等管理措施对NO排放量和排放系数的影响.收集相关文献共计49篇（发表于2006~2021年）.结果表明，玉麦轮作、茶园和果园体系年排放量平均值分别为1.44、7.45和0.92 kg ·hm-2，在这3个体系间有显著性差异（P<0.05），稻麦轮作旱地阶段和蔬菜季节排放量平均值分别为2.13 kg ·hm-2和2.09 kg ·hm-2.在玉麦轮作、稻麦轮作旱地阶段和茶园体系中，NO排放量均与施氮量呈正相关关系（P<0.01），但在蔬菜和果园体系中二者无显著相关性.玉麦轮作、稻麦轮作旱地阶段、蔬菜、茶园和果园体系排放系数平均值分别为0.31%、0.71%、0.96%、1.74%和0.13%，除玉麦轮作分别与稻麦轮作旱地阶段和蔬菜体系间的差异不显著外（P>0.05），在其余体系间均有显著性差异（P<0.01）.由于各体系间排放系数差异大，在编制区域或全国农田NO排放清单时，有必要对各作物体系采用不同的排放系数.减量施氮仅在减氮比例高于25%时可显著降低NO排放量（36%），但对排放系数的影响不显著.由于减氮比例过高可能会造成作物减产，尚需进一步确定既不影响作物产量又降低NO排放的减氮比例.有机肥替代化肥在土壤有机碳含量低［ω（SOC）<15 g ·kg-1］或酸性（pH<7）条件下以及配施新型增效氮肥在玉麦轮作农田中可显著降低NO排放量（-46%~-38%）和排放系数（-62%~-45%），施用生物质炭的影响不显著.可为不同田间条件下分别采取有效的NO减排措施提供依据. |
| 英文摘要 |
| Agroecosystems are a significant source of nitric oxide (NO), a potent atmospheric pollutant. It has been well documented that the NO emissions from upland cropping systems and their emission factors are large relative to those from paddy fields. However, a clear understanding of their uncertainty and regulating factors is still lacking. To date, various field experiments have been conducted to investigate NO emissions and mitigation, providing an opportunity for a Meta-analysis. The aims of this study were to 1 investigate the uncertainty and regulating factors of NO emissions and emission factors from maize-winter wheat rotations, non-waterlogging period in rice-winter wheat rotations, vegetable fields, tea plantations, and fruit orchards across China by extracting data from peer-reviewed publications, and 2 quantify the mitigation potential of management practices, such as reducing nitrogen fertilizer input, organic substitution with chemical fertilizers, and application of enhanced-efficiency nitrogen fertilizers or biochar by performing a pairwise Meta-analysis. A total of 49 references (published from 2006 to 2021) were collected. The results showed that annual NO emissions from the maize-winter wheat rotations, tea plantations, and fruit orchards averaged 1.44, 7.45, and 0.92 kg·hm-2, respectively, with significant differences among the three cropping systems (P<0.05). The seasonal NO emissions from the non-waterlogging period in rice-winter wheat rotations and vegetable fields within a single growth period averaged 2.13 kg·hm-2 and 2.09 kg·hm-2, respectively. The NO emissions positively related to nitrogen inputs in the maize-winter wheat rotations, non-waterlogging period in rice-winter wheat rotations, and tea plantations (P<0.01) but not in the vegetable fields and fruit orchards. The emission factors averaged 0.31%, 0.71%, 0.96%, 1.74%, and 0.13% in the maize-winter wheat rotations, non-waterlogging period in rice-winter wheat rotations, vegetable fields, tea plantations, and fruit orchards, respectively, with significant differences among the cropping systems (P<0.01), except between the maize-winter wheat rotations and non-waterlogging period in rice-winter wheat rotations or vegetable fields (P>0.05). Considering the substantial differences in emission factors among the cropping systems, a specific emission factor for each system should be applied when estimating an agricultural NO budget at a regional or national scale. Reducing nitrogen input only mitigated NO emissions (by 36%) at a reducing nitrogen ratio above 25% but did not impact emission factors. An optimal reducing nitrogen ratio has to be further evaluated without crop productivity penalties. Organic substitution in soils with organic carbon content<15 g·kg-1 or pH<7 and application of enhanced-efficiency fertilizers in the maize-winter wheat rotation simultaneously mitigated NO emissions (by -46%- -38%) and emission factors (by -62%- -45%). By contrast, biochar amendment had no significant effects on either NO emissions or emission factors. These findings highlight a possibility of choosing an effective NO mitigation strategy under specific field conditions. |
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