Rhizosphere priming can promote mobilisation of N-rich compounds from soil organic matter
Rhizosphere priming can promote mobilisation of N-rich compounds from soil organic matter
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DOI：
10.1016/j.soilbio.2014.11.027
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发表时间：
2015-02
影响因子：
9.7
通讯作者：
Conor J. Murphy;E. Baggs;N. Morley;D. Wall;E. Paterson
中科院分区：
文献类型：
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作者：
Conor J. Murphy;E. Baggs;N. Morley;D. Wall;E. Paterson
土壤有机质（SOM）是植物生长所需养分的主要储存库，但这些养分的有效性依赖于微生物生物量介导的转化。已知土壤中添加不稳定碳会改变SOM周转（引发效应，PE），但对此的理解有限，特别是对总氮（N）通量的影响。在这里，我们研究了两种土壤中有机质在引发和非引发条件下的C和N通量之间的关系。稳定同位素（13 C和15 N）被用来测量总的C和N通量从SOM和区分SOM矿化由于启动和从基础mineralisation.13 C-葡萄糖每天添加到模拟的效果，除了不稳定的C对SOM-C和-N矿化根际。此外，葡萄糖增加总的N和C矿化SOM。然而，矿化通量的C-到-N的比例从'引发' SOM为5：1，而C-到-N的比例的基础矿化通量为20：1，表明引发作用于特定的有机质池。这一结果是一致的概念，启动是一个独特的N-开采响应的微生物生物量，而不是加速的基础通量。我们的数据表明，C和N通量没有直接联系，通过他们的总化学计量SOM。这是由于相对于矿化通量和源池的动态性质，OM的异质性和整体被动性，以及在启动系统中富N化合物的矿化。
Soil organic matter (SOM) is the dominant store of nutrients required for plant growth, but the availability of these nutrients is dependent on transformations mediated by the microbial biomass. The addition of labile C to soil is known to alter SOM turnover (priming effect, PE), but understanding of this is limited, particularly with respect to impact on gross nitrogen (N) fluxes. Here we examined relationships between C and N fluxes from SOM under primed and non-primed conditions in two soils. Stable isotopes (13C and15N) were used to measure gross C and N fluxes from SOM and to differentiate between SOM mineralised due to priming and that from basal mineralisation.13C-glucose was added daily to simulate the effect of addition of labile C on SOM-C and –N mineralisation within the rhizosphere. Addition of glucose increased both gross N and C mineralisation from SOM. However, the C-to-N ratio of the mineralised flux from ‘primed’ SOM was 5:1, whereas the C-to-N ratio of the basal mineralised flux was 20:1 indicating that priming acted on specific organic matter pools. This result is consistent with the concept that priming is a distinct N-mining response of the microbial biomass, as opposed to an acceleration of the basal flux. Our data suggest that C and N fluxes are not directly linked through their gross stoichiometry in SOM. This is due to the heterogeneity and overall passiveness of OM relative to the dynamic nature of mineralisation fluxes and source pools, and in primed systems the mineralisation of N-rich compounds.