Rhizosphere priming regulates soil organic carbon and nitrogen mineralization: The significance of abiotic mechanisms
Rhizosphere priming regulates soil organic carbon and nitrogen mineralization: The significance of abiotic mechanisms
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根际引发调节土壤有机碳和氮矿化：非生物机制的意义
DOI：
10.1016/j.geoderma.2020.114877
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发表时间：
2021-03-01
期刊：
影响因子：
6.1
通讯作者：
Gunina, Anna
中科院分区：
文献类型：
--
作者：
Jiang, Zhenhui;Liu, Yizhen;Gunina, Anna
活根对土壤有机碳（SOC）和氮（SON）共矿化的影响以及根际启动效应（RPE）的驱动机制尚不清楚。此外，对于根系通过破坏有机-矿物结合而加速土壤有机质（SOM）流失的非生物机制是否参与其中，人们仍然知之甚少。以3种水稻土（C-3）为研究对象，在玉米（C-4植物）栽培条件下，研究了生物和非生物过程对RPE和总氮矿化（GNM）的影响。土壤全氮（1.79和3.3 g kg（-1）土）和氧化铁（1.1和2.2 g kg（-1）土）含量分别高、低，呈现高铁/低氮、低铁/低氮和低铁/高氮的组合。在玉米栽培的第86天，分别采用c -13天然丰度法和n -15池稀释法测定rpe和GNM。活根提高原生有机碳矿化70.4 ~ 204%，GNM提高118 ~ 382%。正如预期的那样，生物机制促进了RPEs（“微生物激活”和“微生物N挖掘”），这是由于植物存在时土壤微生物生物量C和胞外酶活性的增加，以及在未种植的土壤中，启动SOM的C/N比低于原始SOM。在低铁/低氮与低铁/高氮土壤中发现了更高的RPEs和通过更强的“微生物N挖掘”相对启动的N矿化。与预期相反，在高铁/低氮氧化土壤中，相对于低铁氧化土壤，RPEs和相对启动N矿化更大。在高铁土壤中，SOM来源的铁结合C的下降幅度最大，根系来源的铁结合C的增加幅度最大，这是因为根系渗出物从Fe结合的SOM中释放出更多的C，并与铁氧化物共沉淀。这表明非生物过程参与了RPEs，根系分泌物通过从铁有机络合物中释放碳来促进土壤碳的流失。因此，本研究表明，生物-非生物耦合过程可以调节RPEs。
The effect of living roots on the co-mineralization of soil organic carbon (SOC) and nitrogen (SON) and driving mechanisms of the rhizosphere priming effect (RPE) remains unclear. Moreover, it is still poorly understood whether the abiotic mechanisms, whereby roots accelerate soil organic matter (SOM) loss by destabilizing organo-mineral associations, are involved. Biotic and abiotic processes involved in the RPE and gross N mineralization (GNM) were investigated using three paddy soils (C-3) under maize (C-4 plant) cultivation. The soils had high and low total N (1.79 and 3.3 g kg(-1) soil) as well as iron- (Fe-) (hydr-) oxide (1.1 and 2.2 g kg(-1) soil) contents, which gave the following combinations: high-Fe/low-N, low-Fe/low-N, and low-Fe/high-N. The RPEs and GNM were measured using a C-13-natural abundance approach and N-15-pool dilution technique, respectively, on day 86 of maize cultivation. Living roots enhanced native SOC mineralization by 70.4-204% and GNM by 118-382%. As expected, biotic mechanisms contributed to RPEs (`microbial activation' and 'microbial N-mining') that was supported by the increase of soil microbial biomass C and extracellular enzyme activities in presence of plant, and the lower C/N ratio of primed SOM than the original SOM in unplanted soils. Higher RPEs and relative primed N mineralization via stronger 'microbial N-mining' were found in low-Fe/low-N vs low-Fe/high-N soils. In contrast to expectations, the RPEs and relative primed N mineralization were greater in high-Fe/low-N versus low-Fe oxide soils. The strongest decrease in SOM-derived Fe-bound C and increase in root-derived Fe-bound C were observed in the high-Fe soil, because root exudates liberated more C from Fe-bound SOM and co-precipitated with Fe oxides. This shows that the abiotic process was involved in RPEs whereby root exudates promoted soil C loss by releasing it from Fe-organic complexes. Thus, this study demonstrated that coupled biotic-abiotic processes could regulate RPEs.