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Rhizodeposition mediates the effect of nitrogen and phosphorous availability on microbial carbon use efficiency and turnover rate
Soil Biology and Biochemistry ( IF 9.7 ) Pub Date : 2020-01-08 , DOI: 10.1016/j.soilbio.2020.107705
Bahareh Bicharanloo , Milad Bagheri Shirvan , Claudia Keitel , Feike A. Dijkstra

Soil microorganisms affect both the formation and decomposition of soil organic carbon (SOC). We investigated how nitrogen (N, 25 vs. 100 kg N ha−1) and phosphorus (P, 10 vs. 40 kg P ha−1) fertilisation influenced microbial C use efficiency (CUE) and turnover rate in soil planted with two wheat genotypes, and to what degree these parameters were associated with microbial use of root- and soil-derived C (MBCroot and MBCsoil, respectively). We used a H218O labeling method to quantify CUE and turnover rate, and a continuous 13CO2 plant labelling method to characterise MBCroot and MBCsoil. We found that N fertilisation decreased CUE and slowed down turnover rate, but only at the highest P-level. In contrast, N fertilisation increased MBCsoil at high P, while it increased MBCroot at low P. MBCsoil was negatively and MBCroot was positively related to CUE and microbial turnover rate. Our results suggest that microbes that used more labile root-derived C built up their biomass more efficiently than microbes using more recalcitrant soil-derived C. A more efficient use of root-derived C could enhance the microbially mediated formation of root-derived SOC, but the higher turnover rate and associated C recycling may counter this effect. In contrast, the lower CUE and turnover rate of microbes using more soil-derived SOC suggests that these microbes spent more C on maintenance due to C limitation, which particularly occurred under high N and high P fertilisation. We conclude that fertiliser-induced changes in root-derived C availability play an important role in CUE, MBC pools and microbial turnover rate, ultimately affecting SOC sequestration.



中文翻译:

根际沉积介导氮和磷的有效性对微生物碳利用效率和周转率的影响

土壤微生物会影响土壤有机碳(SOC)的形成和分解。我们调查了氮肥(N,25 vs. 100 kg N ha -1)和磷(P,10 vs. 40 kg P ha -1)的施肥如何影响两种小麦种植的土壤中微生物碳利用效率(CUE)和周转率基因型,以及这些参数在多大程度上与根和土壤来源的碳(分别为MBC和MBC土壤)的微生物利用有关。我们使用H 2 18 O标记法定量CUE和周转率,并使用连续13 CO 2植物标记法表征MBC和MBC土壤。我们发现氮肥降低了CUE并减慢了周转率,但仅在最高P水平下。相反,氮肥在高磷下增加了MBC土壤,而在低磷下增加了MBC。MBC土壤为负值,MBC为负与CUE和微生物更新率呈正相关。我们的结果表明,与使用更多顽固的土壤来源的C的微生物相比,使用更多不稳定的来源C的微生物更有效地建立其生物量。更有效地利用源自根的C可以增强微生物介导的源自根的SOC的形成,但是更高的周转率和相关的碳回收可以抵消这种影响。相反,使用更多土壤来源的SOC降低微生物的CUE和周转率表明,由于C限制(特别是在高氮和高P施肥下发生),这些微生物在维护上花费了更多的C。我们得出的结论是,肥料诱导的根源C可用性变化在CUE,MBC库和微生物周转率中起重要作用,最终影响SOC隔离。

更新日期:2020-01-08
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