College of Resources and Environment, Hunan Agricultural University, Changsha, Hunan 410128, P.R. China; Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan Province, 410125. China.; Hunan Provincial Key Laboratory for Rural Ecosystem Health in the Dongting Lake Area, Changsha, 410128, P.R. China.
Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan Province, 410125. China.
Sci Total Environ. 2020 Nov 15;743:140808. doi: 10.1016/j.scitotenv.2020.140808. Epub 2020 Jul 7.
In paddy soil, the root exudates strongly influence the microbial activity and soil organic matter (SOM) mineralisation. However, the stoichiometric regulation of the mineralisation of root exudates and their priming effect on paddy soil remains unclear. Thus, we used manipulative laboratory incubations to measure the mineralisation of root exudates and the subsequent priming effect in paddy soil under different stoichiometric conditions. In this study, root exudates (simulated by C-labelled glucose, alanine, and oxalic acid) were added to the paddy soil along with four different amounts of N and P. The addition of simulated root exudates (SREs) enhanced the total CO and CH emissions. The mineralisation of SREs decreased by 20-45% after the addition of N and P when compared with exclusive SREs application. The addition of N and P inhibited the SREs-derived CH emissions when compared with SREs application alone. The mineralisation of soil organic matter (SOM) increased with SREs application, thereby generating a positive priming effect for CO and CH emissions. However, the priming effect for CO and CH emissions was reduced with increased amounts of N and P. Furthermore, the addition of SREs with increasing N and P significantly enhanced the microbial SREs-derived C-use efficiency. Structural equation models indicated that NH-N and Olsen P negatively influenced the priming effect, whereas the microbial biomass and enzyme stoichiometry positively influenced the priming effect. In conclusion, our data suggest that SREs combined with increasing amounts of N and P could meet microbial stoichiometric demands and regulate microbial activity, which finally inhibited the mineralisation of SREs-C and the priming effect on paddy soil and positively affected C sequestration.
在稻田土壤中，根分泌物强烈影响微生物活性和土壤有机物质（SOM）矿化。然而，根分泌物矿化的化学计量调节及其对稻田的激发效应仍不清楚。因此，我们使用操纵性实验室培养来测量不同化学计量条件下根分泌物的矿化和随后对稻田的激发效应。在这项研究中，根分泌物（通过 C 标记的葡萄糖、丙氨酸和草酸模拟）与不同数量的 N 和 P 一起添加到稻田土壤中。添加模拟根分泌物（SREs）增加了总 CO 和 CH 的排放。与单独添加 SREs 相比，添加 N 和 P 后 SREs 的矿化减少了 20-45%。与单独添加 SREs 相比，添加 N 和 P 抑制了 SREs 衍生的 CH 排放。土壤有机物质（SOM）的矿化随着 SREs 的应用而增加，从而对 CO 和 CH 的排放产生正激发效应。然而，随着 N 和 P 的增加，CO 和 CH 的激发效应减少。此外，随着 N 和 P 的增加，添加 SREs 显著提高了微生物 SREs 衍生的 C 利用效率。结构方程模型表明，NH-N 和 Olsen P 对激发效应有负面影响，而微生物生物量和酶化学计量对激发效应有积极影响。总之，我们的数据表明，SREs 与增加的 N 和 P 结合可以满足微生物化学计量的需求并调节微生物活性，最终抑制 SREs-C 的矿化和对稻田的激发效应，并对 C 封存产生积极影响。
