National Natural Science Foundation of China (Nos. 31370527, 0870414) and Initial Scientific Research Fund of Doctors in Weifang University (No.2019BS12)
利用IsoSource模型三源区分玉米根际土壤CO2释放来源（根源呼吸、土壤无机碳与有机碳释放），研究玉米根际效应对石灰性土壤无机碳与有机碳释放的影响。在玉米拔节期（24～53 d）、抽穗期（54～66 d）和灌浆期（67～99 d）末分别破坏性取样，测定根系、土壤有机碳和无机碳的13C含量等指标；自拔节期开始至生育期末，每隔3d测定种植玉米与不种玉米的土壤呼吸CO2量以及13C-CO2含量。结果表明，利用IsoSource软件三源区分土壤CO2的排放，土壤CO2排放累计量以根源呼吸贡献为主（48.0%），其次为土壤有机碳（31.2%），最小为土壤无机碳（20.8%）。玉米对土壤无机碳与有机碳释放均表现为正根际效应，从拔节期至生育期末，种植玉米土壤有机碳与无机碳的释放分别较不种植土壤多65%和156%。土壤无机碳对于稳定全球碳库和调节大气CO2浓度具有重要意义，若忽视石灰性土壤无机碳对土壤CO2释放的贡献，有可能高估土壤有机碳的分解。
[Objective] In calcareous soil, CO2in rhizosphere soil comes from at least three sources, i.e., respiration of roots, decomposition of soil organic C (SOC) and dissolution of soil inorganic C (SIC). Owing to technical limitations in partitioning CO2 by source, how rhizosphere effects affect SOC decomposition and SIC dissolution is still an issue not yet clarified. Therefore, an in-lab pot experiment using calcareous soil collected from a farmland of North China to grow maize in an attempt to investigate rhizosphere effects of summer maize plants on release of CO2 from SOC and SIC, using the IsoSource model to partition CO2 in the rhizosphere by source.[Method] At the end of the elongation (24-53 days), heading (54-66 days) and grain-filling (67-99 days) stages of the summer maize, destructive sampling of maize rhizospheres was carried out separately for analysis of content of 13C from root, SOC and SIC, separately. During the period from the beginning of the elongation stage to the end of the maize growth stage, soil respiration and 13C content in the soil with or without maize planted was monitored at a three-day interval with the aid of the IsoSource software.[Result] Results show that to the total soil CO2 emission, root respiration contributed 48.0%, SOC did 31.2% and SIC did 20.8%. During the period from the elongation stage to the end of the summer maize season, CO2 emission from SOC and from SIC in the pot with maize planted was 65% and 156% higher than their respective ones in the pot without maize planted.[Conclusion] This experiment indicates that SIC plays a significant role in stabilizing global C pool and regulating atmospheric CO2 concentration. If the contribution of SIC to soil CO2 emission in calcareous soils is ignored, the amount of CO2from SOC decomposition may be overestimated, which will inevitably affect quantification of the priming effects of SOC. This study will help reduce uncertainties in of soil C budgeting for farmlands of calcareous soil in North China.
孙昭安,赵诣,朱彪,陈清,曹慧,何敏毅,孟凡乔.玉米生长对石灰性土壤无机碳与有机碳释放的根际效应[J].土壤学报,2021,58(4):998-1007. DOI:10.11766/trxb201911210581 SUN Zhaoan, ZHAO Yi, ZHU Biao, CHEN Qing, CAO Hui, HE Minyi, MENG Fanqiao. Rhizosphere Effects of Maize on Inorganic and Organic Carbon Release in Calcareous Soils[J]. Acta Pedologica Sinica,2021,58(4):998-1007.复制