EGU22-5018
https://doi.org/10.5194/egusphere-egu22-5018
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Nitrogen use efficiency of plant species matters: CO2 emission from soil inorganic carbon and its temperature dependence in a calcareous soil

Lichao Fan1, Jingjing Tao1,2, Guodong Shao3, Juanjuan Ai4, and Kazem Zamanian1
Lichao Fan et al.
  • 1Department of Soil Science of Temperate Ecosystems, University of Göttingen, Göttingen 37077, Germany
  • 2College of Natural Resources and Environment, Northwest A&F University/Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, MOA, Yangling 712100, Shaanxi, China
  • 3Department of Soil Science of Tropical and Subtropical Ecosystems, University of Göttingen, Göttingen 37077, Germany
  • 4Department of Biogeochemistry of Agroecosystems, University of Göttingen, Göttingen 37077, Germany

Terrestrial ecosystems play a significant role in global warming by regulating CO2 concentration in the atmosphere. A comprehensive understanding of carbon (C) sources and stocks in soils, as well as the driving mechanisms, are critical to reducing CO2 emission from soil and thus mitigating climate change. To date, most studies have solely focused on processes involving soil organic C (SOC), but few studies have addressed the potential contribution of soil inorganic C (SIC) mostly CaCO3 pool to ecosystem C fluxes. SIC can potentially be a regulator of atmospheric CO2. However, so far the effects of plant species (i.e. variations in nitrogen (N) demand and N use efficiency (NUE)) as well as soil temperature on SIC-derived CO2 are unclear. We hypothesized that 1) relatively less SIC-derived CO2 is expected from soils covered under plant species with lower N demand and higher NUE. We conducted a 4-month field experiment from June to October 2021 at the research station of the University of Göttingen in Deppoldshausen (51.58oN, 9.97oE) with ca. 6% CaCO3 equivalent in the topsoil. We analyzed the effects of two plant species 1) wheat (high N demand and low NUE), 2) legume (low N demand and high NUE) and two N fertilization (urea) levels, 1) low (50 kg N ha-1), 2) high (200 kg N ha-1) on CO2 emission out of SIC. Each treatment had four replicate plots (1×1 m2), and at least a 0.5 m gap was established between plots. We measured CO2 fluxes weekly by using the static chamber method. The δ13C natural abundance was used to determine the contribution of SIC and SOC in the emitted CO2. The total CO2 emission and its δ13C signature increased with soil temperature, indicating that the portion (%) of SIC-derived CO2 was stimulated by temperature (oC) (slope = 0.33). The portion of SIC-derived CO2 stimulated by temperature increased faster under wheat than under legume (slope = 0.36 vs. 0.26), especially under high N treatment (slope = 0.65 vs. 0.54). The portion of SIC-derived CO2 under wheat (13.0%) was higher than that under legume (11.3%). Moreover, the portion of SIC-derived CO2 was 1.2% higher under wheat than under legume at high N fertilization level, whereas it was increased to 2.2% under low N fertilization. This indicates a significant role of plant species with different N demand and NUE on dynamics of SIC pool and its contribution in CO2 emission from soil. The rate of SIC-derived CO2 was comparable between wheat and legume under high N fertilization, but it was 1.6 times higher under wheat than that under legume at low N fertilization. The contribution of SIC-derived C to the atmosphere was ~63.7 g C m-2 yr-1 under legume with low N demand vs. ~82.1 g C m-2 yr-1 under wheat with high N demand. In this regard, the impacts of plant species and their N demand and NUE are important controlling factors determining the dynamics of the SIC pool in agroecosystems.

How to cite: Fan, L., Tao, J., Shao, G., Ai, J., and Zamanian, K.: Nitrogen use efficiency of plant species matters: CO2 emission from soil inorganic carbon and its temperature dependence in a calcareous soil, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5018, https://doi.org/10.5194/egusphere-egu22-5018, 2022.