• ISSN 1008-505X
  • CN 11-3996/S

控释氮肥结合减氮对冬绿肥−夏玉米轮作体系土壤氧化亚氮排放的影响

The effects of controlled-release nitrogen fertilizer combined with nitrogen reduction on soil nitrous oxide emissions in winter green manure-summer maize rotation system

    摘要
  • 摘要:
    目的 研究首都圈控释氮肥结合减氮对冬绿肥−夏玉米轮作体系土壤氧化亚氮排放(N2O)的影响，为该地区合理节肥减排提供理论依据与技术支撑。
    方法 在天津连续进行了2年田间试验(2023、2024年)，试验设置冬闲+常规施氮(F100)、绿肥+常规施氮(GF100)、绿肥+控释氮肥(GS100)、绿肥+70%控释氮肥(GS70)、绿肥+70%控释氮肥+生物炭(GS70C)、绿肥+55%控释氮肥+生物炭(GS55C)，共计6个处理。测定玉米产量、N2O周年排放速率及累积排放量、土壤pH值、碳氮含量及土壤酶活性。
    结果 GF100处理玉米产量最高，GS100次之，均显著高于F100处理。GS70与GS70C处理保持稳产，而GS55C产量较F100两年分别降低了12.5%和7.2%。与F100相比，GF100处理的N2O周年累积排放量2023年无显著变化，2024年显著增加了7.6%，而GS100较GF100两年分别减排11.7% 和 19.0%，且GS70处理较 GS100 处理两年进一步降低N2O排放量22.3%和15.3%。与GS70相比，GS70C处理的N2O排放量两年均无显著差异，而GS55C处理则显著下降了14.5%与15.4%。添加生物炭可增加土壤pH值，GS70C与GS55C处理的土壤pH值最高。与F100相比，GF100显著增加了土壤铵态氮与硝态氮含量，5个含绿肥处理均显著提升了β-葡萄糖苷酶(BG)、β-纤维二糖苷酶(CEL)活性。控释氮肥显著降低了硝酸还原酶(NR)与亚硝酸还原酶(NIR)的活性，GS100处理的土壤NR和NIR活性较GF100显著下降18.4%和14.8%，GS70、GS70C、GS55C处理的NR和NIR活性较GS100又进一步显著降低；相同控释氮肥施用量下，配施生物炭对NR活性无影响，但显著降低了NIR活性。相关分析结果表明，玉米产量与土壤碳氮比成显著负相关，与土壤酶活性(脲酶、NR、NIR)、土壤铵态氮、硝态氮、全氮含量存在显著正相关关系。N2O排放与土壤硝态氮含量、NR和NIR显著正相关，与土壤pH值、有机碳、全氮含量、BG、CEL呈显著负相关。
    结论 绿肥与常规施氮结合会增加N2O排放，与控释氮肥配合则会降低N2O排放，且控释氮肥减量能进一步降低N2O排放。综合考虑玉米产量和N2O排放，绿肥配施控释氮肥的基础上减施氮肥30%是首都圈冬玉米-夏绿肥轮作体系中土壤N2O减排的有效措施。

     

    Abstract:
    Objectives This study aimed to investigate the effect of controlled-release nitrogen fertilizer and nitrogen reduction on soil nitrous oxide (N2O) emissions in the winter green manure-summer maize rotation system of the capital region.
    Methods A field experiment was carried out in Tianjin consecutively in 2023 and 2024, the six treatments included winter fallow+conventional urea (F100), green manure+conventional urea (GF100), green manure+controlled-release urea (GS100), green manure+controlled-release urea under 30% N reduction (GS70), GS70+biochar (GS70C), and green manure+controlled-release urea under 45% N reduction+biochar (GS55C). Maize yield, annual emission flux and cumulative emission of N2O, soil pH, carbon and nitrogen content, and soil enzyme activity were measured.
    Results GF100 treatment exhibited the highest maize yield, followed by GS100 treatment, both significantly higher than F100 treatment, while GS55C treatment was recorded 12.5% and 7.2% lower yield in 2023 and 2024, respectively. Compared to F100, GF100 exhibited comparable annual N2O emissions in 2023 but 7.6% higher N2O emissions in 2024. GS100 reduced annual N2O emissions by 11.7% and 19.0% respectively over two years compared to GF100. The GS70 treatment further reduced N2O emissions by 22.3% and 15.3%, relative to GS100 treatment. There was no significant difference in N2O emissions between GS70C and GS70, while the N2O emissions of GS55C treatment was 14.5% and 15.4% lower than those of GS70C. Adding biochar can increase soil pH, with the highest pH values observed in GS70C and GS55C treatments. Compared to F100, GF100 significantly increased the content of soil ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N). All the five green manure treatments significantly enhanced the activities of β-glucosidase (BG) and β-cellulase (CEL). Controlled release nitrogen fertilizer treatments significantly reduced the activities of nitrate reductase (NR) and nitrite reductase (NIR). Compared with GF100, the soil NR and NIR activities in GS100 treatment decreased significantly by 18.4% and 14.8%, respectively. The treatments of GS70, GS70C, and GS55C further reduced the activity of NR and NIR, and under the same application rate of controlled-release nitrogen fertilizer, the addition of biochar had no effect on NR activity, but significantly reduced NIR activity. The correlation analysis results indicated that maize yield was negatively correlated with soil C/N, and positively correlated with soil enzyme activity (urease, NR, NIR), soil NH4+-N, NO3−-N, and total nitrogen content. N2O emissions were significantly positively correlated with soil NO3−-N, NR, and NIR, and negatively correlated with soil pH, organic carbon, total nitrogen content, BG, and CEL.
    Conclusions The combination of green manure and conventional fertilization increases N2O emissions, while the combination with controlled-release nitrogen fertilizer significantly reduced N2O emissions, and reducing the nitrogen input will further strength the emission reduction effects. Comprehensively considering the maize yield and N2O emission reduction, green manure combined with controlled-release nitrogen fertilizer under 30% reduction is recommended for maintaining stable maize yield and reducing soil N2O emission in the capital area.

     

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