Application of a triple 15N tracing technique to elucidate N transformations in a UK grassland soil
Application of a triple 15N tracing technique to elucidate N transformations in a UK grassland soil
复制标题
DOI：
10.1016/j.geoderma.2020.114844
复制
发表时间：
2021-03
期刊：
影响因子：
6.1
通讯作者：
N. Loick;E. Dixon;G. Matthews;C. Müller;V. Ciganda;M. López‐Aizpún;M. Repullo;L. Cárdenas
中科院分区：
文献类型：
--
作者：
N. Loick;E. Dixon;G. Matthews;C. Müller;V. Ciganda;M. López‐Aizpún;M. Repullo;L. Cárdenas
为了确定土壤中N2 O排放的生产和消费途径以及时间动态，本研究使用15 N标记的底物N，使用Ntrace分析工具量化了潜在的总N转化率，并将其与N排放联系起来。在三个实验中，每个12个土芯在实验室培养系统中培养，以测量气体排放，而在相同条件下的平行培养设置在7个时间点的破坏性土壤采样。使用三重标记技术（应用NH 4 NO3与NH 4 +-N或NO3−-N，或两者都被15 N标记），本研究调查了55，70和85%的水填充孔隙空间的影响（被认为促进硝化，硝化和反硝化，以及反硝化，分别）对气态氮排放的粘土和调查的来源和过程中导致N2 O排放。硝化的NO3-从施加的NH 4+，15 N示踪工具Ntrace被用来量化固定的NO3-和NH 4+，NH 4+的氧化，矿化的有机氮和随后的硝化作用，通过分析土壤中的15 N。计算了总转化率，表明添加的NO3-和来自硝化的添加的NH 4+的NO3-的相对重要性。（有机氮氧化为NO3-），在55%水填充孔隙（WFPS）时最高，随着WFPS的增加，其对氮转化过程的贡献减少，而硝化作用（NH 4+氧化为NO3−）在70%WFPS时贡献最大。反硝化作用的贡献随着WFPS的增加而增加，但只有在85% WFPS时才成为主导。虽然反硝化作用在高WFPS下仍然是最重要的，硝化作用在较低WFPS下仍然是最重要的，但实际的% WFPS值并不像预期的那样，并且突出了这样一个事实，即WFPS是一个贡献者，但不是确定发生的N转化过程类型的唯一/最重要的参数。
To identify the production and consumption pathways and temporal dynamics of N2O emitted from soil, this study uses15N-labelled substrate-N to quantify the underlying gross N transformation rates using theNtraceanalysis tool and link them to N-emissions. In three experiments twelve soil cores each were incubated in a lab incubation system to measure gaseous emissions, while parallel incubations under the same conditions were set up for destructive soil sampling at 7 time points. Using the triple labelling technique (applying NH4NO3with either the NH4+-N or the NO3−-N, or both being15N labelled), this study investigated the effects of 55, 70 and 85% water filled pore space (deemed to promote nitrification, both nitrification and denitrification, and denitrification, respectively) in a clay soil on gaseous N emissions and investigates the source and processes leading to N2O emissions.To assess the utilisation of applied NO3−vs. nitrified NO3−from applied NH4+, the15N tracing toolNtracewas used to quantify the rates of immobilisation of NO3−and NH4+, oxidation of NH4+, mineralisation of organic N and subsequent nitrification by the analysis of the15N in the soil. Gross transformation rates were calculated, indicating the relative importance of added NO3−and NO3−derived from nitrified added NH4+.Results show an important contribution of heterotrophic nitrification (organic N oxidation to NO3−) which was highest at the 55% water filled pore space (WFPS), decreasing in its contribution to N-transformation processes with increasing WFPS, while nitrification (NH4+oxidation to NO3−) was contributing the most at 70% WFPS. The contribution of denitrification increased with increasing WFPS, but only became dominant at 85% WFPS. While denitrification still showed to be most important at high and nitrification at lower WFPS, the actual % WFPS values were not as expected and highlight the fact that WFPS is a contributor, but not the sole/most important parameter determining the type of N-transformation processes taking place.