EGU2020-5139, updated on 12 Jun 2020
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Effects of elevated CO2 on nitrogen cycling in soil and alfalfa leaves

Yuhan Zong1, Jing Hu2, Zhi Zhuang1, Yuliang Li1, and Weiguo Liu2
Yuhan Zong et al.
  • 1School of Water and Environment, Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education, Chang’an University, Xi’an, 710064, P. R. China
  • 2State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an, 710064, P. R. China

Increased atmospheric CO2 concentration will have an significant impact on the nitrogen cycle of terrestrial ecosystems. The elevation of atmospheric CO2 has become an inevitable trend, and nitrogen is the most important factor affecting plant growth. But it is rare to explore the effect of CO2 on nitrogen cycle by measuring the value of δ15N. The δ15N value as a comprehensive indicator of the nitrogen cycle of the ecosystem, which can not only clarify the migration and transformation of nitrogen, but also effectively indicate the nitrogen limit and nitrogen open level of the ecosystem. Our experiment selected alfalfa (C3 plant) as the research object, then investigated the response of nitrate nitrogen, ammonia nitrogen and absorbable nitrogen to the elevated CO2 concentration in soil and alfalfa leaves under ambient and elevated atmospheric CO2 (500 and 700ppm) in open top chambers. The 15N isotope value was determined by bacterial denitrification , and 15N-gas chromatography (GC-MS) were applied to further analyze the effect of elevated CO2 concentration on nitrogen cycling in soil and plant leaves. The increase of CO2 concentration led to the decline of various inorganic nitrogen levels in soil, and the δ15N in the soil also showed a certain downward trend, but always maintained a positive value. The nitrogen level and δ15N values in alfalfa leaves did not change significantly, showing a small increase. It indicates that there are different degrees of nitrogen loss in the leaves under the influence of different concentrations of CO2. These results are closely related to the fractional distillation of nitrogen isotopes caused by microorganisms in the process of nitrogen morphologic transformation. We briefly reviewed the changes of nitrogen content in soil and plant leaves under elevated CO2, providing new insights into the nitrogen cycle of soils and plants under high CO2 concentrations. It also provides a scientific basis for the protection of soil and plants under the greenhouse effect.

How to cite: Zong, Y., Hu, J., Zhuang, Z., Li, Y., and Liu, W.: Effects of elevated CO2 on nitrogen cycling in soil and alfalfa leaves, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5139,, 2020