我国菜地N2O排放特征及其影响因素

Characteristics and influencing factors of N2O emissions from vegetable fields in China

  • 摘要: 我国蔬菜种植面积和产量均居世界首位。由于肥水投入强度大, 菜地已成为N2O排放的重要源区。通过整合2000—2023年的田间观测数据, 评估我国菜地在作物生长季期间的N2O排放特征及其影响因素。结果表明: 我国菜地N2O平均排放量为7.32 kg(N)·hm‒2; 北方菜地比南方高19.4%; 设施菜地比露天高44.4%; 瓜果类菜地分别比叶菜类和根茎类高59.7%和133.5%。此外, 我国菜地平均N2O排放系数为1.48%; 南方比北方高64.8%; 露天比设施高30.9%; 瓜果类分别比叶菜类和根茎类高7.4%和61.1%。最后, 我国菜地单位产量N2O平均排放量为0.125 kg·t‒1; 南方比北方高40.8%; 露天比设施高28.0%; 瓜果类分别比叶菜类和根茎类高13.1%和273.0%。从全国看, 施氮量与N2O排放量或单位产量排放量均显著正相关, 但对N2O排放系数影响不显著; 相比于单施有机肥或无机肥, 有机无机配施显著提高N2O排放量, 但对排放系数无显著影响; 土壤偏酸或偏碱均显著增加N2O排放量, 同时偏酸也提高排放系数; 过量灌溉增加N2O排放量、排放系数以及单位产量排放量。综上, 我国菜地N2O排放的科学评估及减排要综合考虑地理区域、种植方式、作物类型及不同排放参数的差异性。从全国看, 合理减氮施肥、节水灌溉、酸性土壤改良等均有助于菜地N2O减排。

     

    Abstract: China ranks first globally in both vegetable cultivation area and production. Due to high inputs of fertilizers and irrigation, vegetable fields have become significant sources of nitrous oxide (N2O) emissions. By integrating field observation data from 2000 to 2023, this study assessed the characteristics and influencing factors of N2O emissions during the growing season in Chinese vegetable systems. Results showed that the average N2O emission from vegetable fields was7.32 kg(N)·hm‒2. Emissions were higher in northern China 8.13 kg(N)·hm‒2 than in southern China 6.8 kg(N)·hm‒2, with an increase of 19.4%. Greenhouse vegetable systems 7.93 kg(N)·hm‒2 emitted 44.4% more N2O than open-field systems 5.49 kg(N)·hm‒2. Among crop types, fruit vegetables 8.43 kg(N)·hm‒2 had significantly higher emissions than leafy vegetables 5.28 kg(N)·hm‒2 and root/tuber vegetables 3.61 kg(N)·hm‒2, by 59.7% and 133.5%, respectively. The average N2O emission factor was 1.48%. Southern China (1.78%) showed a 64.8% higher emission factor than the north (1.08%), and open-field systems (1.82%) were 30.9% higher than greenhouse systems (1.39%). Fruit vegetables (1.45%) also exhibited higher emission factors than leafy (1.35%) and root/tuber vegetables (0.90%), by 7.4% and 61.1%, respectively. The yield-scaled N2O emission averaged 0.125 kg·t‒1. This value was higher in southern (0.145 kg·t‒1) than northern regions (0.103 kg·t‒1), and in open-field (0.151 kg·t‒1) than greenhouse systems (0.118 kg·t‒1), with increases of 40.8% and 28.0%, respectively. Fruit vegetables (0.138 kg·t‒1) had higher yield-scaled emissions than leafy (0.122 kg·t‒1) and root/tuber vegetables (0.036 kg·t‒1), by 13.1% and 273.0%. At the national scale, N2O emissions and yield-scaled emissions were significantly positively correlated with nitrogen application rates, while no significant effect was observed on emission factors. Combined application of organic and inorganic fertilizers significantly increased N2O emissions compared to the sole application of either, though it had no significant impact on the emission factor. Both acidic and alkaline soil conditions significantly increased N2O emissions, and acidity also elevated the emission factor. Over-irrigation led to increased N2O emissions, emission factors, and yield-scaled emissions. In conclusion, a comprehensive understanding of regional, agronomic, and crop-type differences in N2O emissions and emission parameters is essential for accurately assessing and mitigating N2O emissions from China’s vegetable systems. Nationwide strategies such as optimized nitrogen fertilization, water-saving irrigation, and acid soil amelioration are recommended to mitigate N2O emissions in intensive vegetable production.

     

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