小麦和玉米生长对土壤碳输入和输出的贡献

孙昭安; 朱彪; 张译文; 李梦雨; 孟凡乔

文章摘要

孙昭安,朱彪,张译文,李梦雨,孟凡乔.小麦和玉米生长对土壤碳输入和输出的贡献[J].农业环境科学学报,2021,40(10):2257-2265.

小麦和玉米生长对土壤碳输入和输出的贡献

Contributions of wheat and maize growth to soil carbon input and output

投稿时间：2021-03-11

DOI：10.11654/jaes.2021-0295

中文关键词: 小麦玉米根际沉积根源呼吸根际激发效应

英文关键词: wheat maize rhizodeposition root-derived respiration rhizosphere priming effect

基金项目:国家重点研发计划项目（2016YFD0201204）；潍坊学院博士科研启动基金项目（2019BS12）

作者	单位	E-mail
孙昭安	潍坊学院生物与农业工程学院/山东省高校生物化学与分子生物学重点实验室, 山东潍坊 261061 中国农业大学资源与环境学院/农田土壤污染防控与修复北京市重点实验室, 北京 100193
朱彪	北京大学生态研究中心/城市与环境学院/地表过程分析与模拟教育部重点实验室, 北京 100871
张译文	山东省招远市农业农村局农业技术推广中心, 山东招远 265499
李梦雨	潍坊学院生物与农业工程学院/山东省高校生物化学与分子生物学重点实验室, 山东潍坊 261061
孟凡乔	中国农业大学资源与环境学院/农田土壤污染防控与修复北京市重点实验室, 北京 100193	mengfq@cau.edu.cn

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中文摘要:

在农业生态系统中，区分土壤外源碳输入和内源碳输出是量化土壤碳平衡的前提。借助碳同位素方法，可以精确区分不同碳源对土壤有机碳（SOC）和二氧化碳（CO₂）的贡献，一方面定量根际沉积碳对土壤碳的输入，另一方面还可以量化根系生长对SOC分解的根际激发效应，进而提高土壤碳平衡评估的精确度。本文整合了关于小麦和玉米¹³C/¹⁴C示踪实验的文献，对作物-土壤系统光合碳分配、向地下部碳输入量、根际土壤CO₂区分以及根际激发效应进行分析，最终明确了小麦和玉米生长对土壤碳输入和输出的贡献。在作物-土壤系统中，小麦光合碳分配到地上部、根系、土壤和土壤释放CO₂的平均比例分别为73.1%、12.5%、4.6%、9.8%，玉米分别为68.4%、16.0%、4.6%和11.1%。小麦和玉米通过根系和根际沉积碳对土壤碳输入量均值分别为1 058 kg·hm^-2和1 025 kg·hm^-2，其中根际沉积碳占地下输入的贡献均值分别为0.45和0.38。小麦和玉米根源呼吸占根际土壤CO₂释放的贡献值均达到50%以上，分别为51.3%和56.7%。小麦和玉米生长促进SOC的分解，根际激发效应平均值分别为172%和15%，若采用传统根去除法来区分土壤呼吸，根际激发效应则会被忽略，这可能导致根源呼吸的高估。小麦和玉米生长过程中释放的净根际沉积碳占地下部净碳输入（根系+根际沉积物）比例分别为27%和22%，如果利用传统洗根法，这部分光合碳量就无法量化，导致输入到地下部的光合碳量被低估。

英文摘要:

In agroecosystem, partitioning exogenous C input and endogenous C release is a prerequisite for quantifying soil C balance. The contribution of different C sources to soil organic C(SOC) and soil CO₂ can be accurately distinguished using the C isotope method. This method can not only quantify soil C input in the form of rhizodeposition but can also estimate the rhizosphere priming effects on SOC decomposition, which increases the accuracy of soil C balance assessments. Through a survey of the literature on ¹³C/¹⁴C tracer experiments, the study analyzed photosynthetic C allocation, belowground C input, different contributions of soil CO₂ emission, and rhizosphere priming effects. The results showed that the photosynthesized C of wheat allocated to aboveground, roots, SOC, and soil CO 2 emissions were 73.1%, 12.5%, 4.6%, 9.8% of the net assimilated C, respectively, and those of maize were 68.4%, 16.0%, 4.6%, and 11.1%, respectivedly. The amounts of the photosynthetic C transferred into soil were 1 058 kg·hm^-2 and 1 025 kg·hm^-2 by wheat and maize, among which the contribution of rhizodeposition was 0.45 and 0.38, respectively. The contribution of root-derived respiration to total soil CO₂ emissions in wheat- and maize-planted soils accounted for 51.3% and 56.7%, respectively. The growth of wheat and maize showed positive rhizosphere priming effects on SOC decomposition, with average magnitudes of 172% and 15%, respectively. If the traditional root exclusion method was used to distinguish soil respiration, the positive rhizosphere priming effects would be ignored, which might lead to the overestimation of root-derived respiration. The net rhizodeposition during the growth of wheat and maize accounted for 27% and 22% of the net belowground C input(root + rhizodeposition), respectively. If the traditional root washing method was used, rhizodeposition could not be quantified, resulting in an underestimation of the net belowground C input.

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