Effect of water-saving irrigation on the N2O dynamics and the contribution of exogenous and endogenous nitrogen to N2O production in paddy soil using 15N tracing
Effect of water-saving irrigation on the N2O dynamics and the contribution of exogenous and endogenous nitrogen to N2O production in paddy soil using 15N tracing
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DOI：
10.1016/j.still.2020.104610
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发表时间：
2020-06
影响因子：
6.5
通讯作者：
Sheng Zhou;Huifeng Sun;J. Bi;Jining Zhang;Shohei Riya;M. Hosomi
中科院分区：
文献类型：
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作者：
Sheng Zhou;Huifeng Sun;J. Bi;Jining Zhang;Shohei Riya;M. Hosomi
节水灌溉技术可以有效地减少稻田的甲烷排放，但由于土壤水分含量的变化，通常会增加一氧化二氮（N2 O）的排放。然而，很少有研究探讨了不同的水分状况对N2 O的生产使用不同种类的外源氮（N）肥料的应用。此外，外源氮肥和土壤内源氮对N_2O产生的贡献尚未阐明。利用一系列蒸渗仪，在本研究中，三种类型的水分管理在水稻栽培中采用：常规灌溉管理（CIM），干湿交替（AWD），和旱作管理（DCM）。以硝酸铵（NH 4 NO3）为基肥、分蘖肥和抽穗肥，将其分为15 N稳定同位素标记的15 NH 4 NO3和NH 415 NO3两组（> 99%）。此外，15 NO3-和15 NH 4+施肥处理的15 N2 O排放通量明显分为两种模式。施用15 NO3 −肥料能迅速释放15 N2 O，而施用15 NH 4+肥料的15 N2 O释放通量增加缓慢，且具有滞后效应，表明反硝化作用是淹水条件下施用15 NO3 −肥料的水稻土15 N2 O释放的主要途径。相反，15 NH 4+可能需要通过硝化作用转化为15 NO3-，然后硝化，最后释放为15 N2 O。此外，硝化-反硝化过程可能会增强N2 O的产生，由于AWD处理的地下水位交替。因此，在水稻生长期的总N2 O排放量是最高的AWD土壤，在CIM处理的2.4倍。在AWD处理中，来自土壤内源氮源的N2 O-N比例较高（占总N2 O排放量的81%），表明土壤干湿交替利用了土壤有机质矿化的内源氮来刺激N2 O的产生。此外，水稻土水分管理影响水稻植株对氮素的吸收。水稻植株的总氮吸收量CIM显著高于AWD和DCM处理。
Water-saving irrigation techniques can effectively mitigate methane emissions from rice fields but typically enhance nitrous oxide (N2O) emissions due to changes in soil moisture content. However, few studies have examined the effect of different water regimes on N2O production using different species of exogenous nitrogen (N) fertilizer application. Furthermore, the contributions of exogenous N fertilizer and endogenous N of soil for N2O productions have not been elucidated. Using a series of lysimeters, three types of water management were employed in rice cultivation in this study: conventional irrigation management (CIM), alternate wetting and drying (AWD), and dry cultivation management (DCM). Ammonium nitrate (NH4NO3) fertilizer was applied as base, tillering, and heading fertilizer, which was then separated into two groups labeled with15N stable isotope (> 99 %) at two different N positions:15NH4NO3and NH415NO3.Higher peaks of N2O flux were observed following drainage of floodwater for AWD and DCM treatments. In addition,15N2O fluxes were clearly separated into two different patterns between15NO3– and15NH4+fertilizer application. Application of15NO3−fertilizer rapidly released15N2O but the15N2O flux for15NH4+fertilizer application slowly increased with a hysteresis effect, suggesting denitrification was the main pathway for15N2O production in paddy soil with15NO3−fertilizer added in a flooded situation. Conversely,15NH4+may need to be converted into15NO3– through nitrification, then denitrified and finally released as15N2O. Furthermore, N2O production was likely enhanced by nitrification–denitrification processes due to the water level alternating near the ground surface for AWD treatment. Consequently, the total N2O emission over the rice growing period was the highest from the AWD soils, at 2.4 times that for CIM treatments. The high proportion of N2O-N derived from soil endogenous N sources (81 % of total N2O emission) in the AWD treatment indicates that the alternating wetting–drying of soil stimulated N2O production using endogenous N mineralized from soil organic matter. Furthermore, water management of paddy soil affected N uptake by rice plants. The total N uptake by rice plants was significantly higher for CIM than for AWD and DCM treatments.