Nitrogen availability alters rhizosphere processes mediating soil organic matter mineralisation
Nitrogen availability alters rhizosphere processes mediating soil organic matter mineralisation
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DOI：
10.1007/s11104-017-3275-0
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发表时间：
2017-05
期刊：
影响因子：
4.9
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
背景和目标土壤的内在氮（N）供应能力对于了解自然植物群落的生产力至关重要，并且对于确定农业土壤的最佳施肥率至关重要。然而，目前尚不清楚养分有效性如何影响植物介导的启动效应，从而驱动土壤有机质矿化和相关的氮通量。方法我们对高产和低产草地土壤中生长的黑麦草应用连续、稳态13C-CO2标记，以量化SOM和根源土壤CO2流出。将养分处理（N、P 和 K）作为重复添加到土壤中，并相对于未改良的种植和休耕土壤评估对源分区土壤 CO2 流出的影响。每周将植物修剪至统一的高度。结果两种土壤中养分有效性的增加导致植物介导的 SOM 矿化减少，而修剪植物大大降低了根系呼吸作用，但增加了 SOM 矿化。向休耕系统添加养分对两种土壤中的 SOM 矿化没有影响。植物生长刺激了 SOM 启动，同时从 SOM 中调动氮，随后植物在高生产力土壤中吸收氮。由于其固有的有机质稳定性较高，在低生产力土壤中未观察到引发，从而导致植物介导的基础 SOM 矿化降低。结论添加养分减少了种植系统中的 SOM 矿化，但对休耕系统没有影响，这表明养分可用性特别改变了植物介导的 SOM 矿化的引发。我们认为，介导启动效应的植物-土壤相互作用是生产力的重要决定因素，并且这些效应的程度可以通过养分可用性和土壤特定控制来改变。
Background and aimsThe intrinsic nitrogen (N) supply capacity of soil is central to understanding the productivity of natural plant communities, and essential in the context of determining optimal fertilization rates for agricultural soils. However, it is largely unknown how nutrient availability affects plant mediated priming effects driving soil organic matter mineralisation and associated N-fluxes.MethodsWe applied continuous, steady-state13C–CO2labelling toLolium perennegrown in high and low productivity grassland soils to allow quantification of SOM- and root-derived soil CO2efflux. Nutrient treatments (N, P and K) were applied as repeated additions to soils, and impacts on source partitioned soil CO2efflux were assessed relative to unamended planted and fallow soils. Plants were clipped to uniform height at weekly intervals.ResultsIncreasing nutrient availability in both soils resulted in a reduction in plant-mediated SOM mineralisation and clipping of plants greatly lowered root-derived respiration but increased SOM mineralisation. Nutrient addition to fallow systems had no effect on SOM mineralisation in either soil. Plant growth stimulated SOM priming, concurrent mobilisation of N from SOM and subsequent plant N uptake in the high productivity soil. Priming was not observed in the low productivity soil due to its greater inherent organic matter stability, resulting in lowered plant-mediated and basal SOM mineralisation.ConclusionsThat addition of nutrients reduced SOM mineralisation in planted systems but had no effect in fallow systems is indicative of nutrient availability specifically altering plant-mediated priming of SOM mineralisation. We suggest that plant-soil interactions mediating priming effects are an important determinant of productivity and that the magnitudes of these effects are modified by nutrient availability and soil-specific controls.