δ15N–N2O signatures in response to N fertilization in a wheat–maize rotation
δ15N–N2O signatures in response to N fertilization in a wheat–maize rotation
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DOI：
10.1007/s10705-021-10123-y
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发表时间：
2021-03
影响因子：
3.1
通讯作者：
Yuying Wang;Wenxu Dong;Yuming Zhang;Xiaoxin Li;Jiafa Luo;Chunsheng Hu
中科院分区：
文献类型：
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作者：
Yuying Wang;Wenxu Dong;Yuming Zhang;Xiaoxin Li;Jiafa Luo;Chunsheng Hu
摘要农田土壤中δ15N-N2O同位素特征对土壤氮肥的响应尚不清楚。因此，我们进行了为期一年的田间试验，以评估在中国北部小麦-玉米轮作中，氮肥(0和400kgN/ha−1年期−1，N0和N400)对土壤表层和土壤剖面(0-3米)δ15N-N2O同位素特征的影响。施氮肥使土壤剖面中的N2O含量增加18-79%。土壤表层和0-0.9m土层的N2O通量分别增加了9倍和1-7倍。相比之下，施氮使土壤剖面中的δ15N-N2O值降低了10-74%。土壤表层和土壤剖面的δ15N-N2O同位素特征值分别降低了18%和33%。冷季和暖季δ15N-N2O同位素特征分别以基质δ15N特征和N同位素分馏为主。结果表明，在无氮处理中，N0处理和N400处理N2O的生成以N3−→ N2O的反硝化步骤为主(99%以上)。施氮后，土壤剖面N2O的生成以NO3-−→ -N2O为主(99%以上)，土壤表层的N2O通量主要来自NO3-−→ -N2O，来自NH4+→ -N2O的N2O较少。总体而言，在中国北方小麦-玉米轮作农田，反硝化作用是土壤N2O转化代谢的主导因素。
AbstractThe responses of δ15N–N2O isotopic signatures to nitrogen (N) fertilization in in situ soils are not yet clear in agricultural field settings. We therefore conducted a 1-year field experiment to assess how N fertilization (0 and 400 kg N ha−1year−1, N0 and N400) affects the δ15N–N2O isotopic signatures both at soil surface and in soil profile (0–3 m) in a wheat–maize rotation in North China. N fertilization increased N2O concentrations by 18–79% in the soil profile. It increased N2O fluxes by 9 times and 1–7 times at the soil surface and 0–0.9 m soil depth, respectively. In comparison, N fertilization reduced δ15N–N2O values by 10–74% in the soil profile. It reduced δ15N–N2O isotopic signatures at the soil surface and in the soil profile by 18% and 33%, respectively. The δ15N–N2O isotopic signature was dominated by substrate δ15N signature and N isotope fractionation during cold and warm seasons, respectively. Our results indicate that denitrification steps of NO3−→ N2O dominated N2O production (over 99%) in the N0 treatment and the N400 treatment during N-fertilizer-free period. Following N fertilization, the NO3−→ N2O dominated N2O production (over 99%) in the soil profile, N2O flux from the soil surface was mostly derived from NO3−→ N2O and less from NH4+→ N2O. Overall, denitrification was found to dominate soil N2O transformation metabolism in the wheat–maize rotation cropland in North China.Graphic abstract