Three-year elevated carbon dioxide concentration does not enhance soil organic carbon quantity due to simultaneously facilitated carbon input and decomposition in a single rice paddy soil evidenced by natural 13C tracing

Shuirong Tang; Yanzheng Wu; Lei Meng; Hidemitsu Sakai; Toshihiro Hasegawa; Xingkai Xu; Zhibin Guo; Weiguo Cheng

doi:10.1016/j.scitotenv.2024.177605

Three-year elevated carbon dioxide concentration does not enhance soil organic carbon quantity due to simultaneously facilitated carbon input and decomposition in a single rice paddy soil evidenced by natural ¹³C tracing

Sci Total Environ. 2024 Nov 18:177605. doi: 10.1016/j.scitotenv.2024.177605. Online ahead of print.

Authors

Shuirong Tang¹, Yanzheng Wu², Lei Meng², Hidemitsu Sakai³, Toshihiro Hasegawa³, Xingkai Xu⁴, Zhibin Guo⁵, Weiguo Cheng⁶

Affiliations

¹ School of Breeding and Multiplication, Sanya Institute of Breeding and Multiplication, Hainan University, Sanya 572025, China; Faculty of Agriculture, Yamagata University, Tsuruoka 997-8555, Japan.
² School of Breeding and Multiplication, Sanya Institute of Breeding and Multiplication, Hainan University, Sanya 572025, China.
³ Institute for Agro-Environmental Sciences, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan.
⁴ State Key Laboratory of Atmospheric Environment and Extreme Meteorology, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
⁵ Soil and Fertilizer Research Institute, Anhui Academy of Agricultural Sciences, Hefei, Anhui 230031, China.
⁶ Faculty of Agriculture, Yamagata University, Tsuruoka 997-8555, Japan. Electronic address: cheng@tds1.tr.yamagata-u.ac.jp.

PMID: 39566636
DOI: 10.1016/j.scitotenv.2024.177605

Abstract

Soil organic carbon (SOC) markedly contributes to maintaining soil nutrient cycling and mitigating climate change. Elevated carbon dioxide concentration ([CO₂]) is widely expected to improve crop yield and increase carbon (C) storage; however, its effects on rice growth and SOC dynamics remain greatly unclear. Therefore, a three-year (2007-2009) chamber experiment with two [CO₂] treatments (380 vs. 680 ppm) was conducted during rice growing seasons. Ultisol soil, taken from a sugarcane (C₄ plant) field on Ishigaki island, Okinawa, was used to grow rice (C₃ plant). The natural ¹³C tracing method was utilized to measure the fraction of SOC derived from the rice plant, and δ¹³C values and concentrations of CO₂ and CH₄ dissolved in soil solutions were determined. Elevated [CO₂] significantly increased rice aboveground biomass (AGB) by 11.8 %-28.8 % and assimilated C content by 12.2 %-28.3 %. However, no significant differences were observed in SOC, total nitrogen (N) content, and the C/N ratios between ambient and elevated [CO₂]. Elevated [CO₂] induced markedly lower δ¹³C values in both plant and soil samples relative to ambient [CO₂]. The annual fractions of plant-derived C input ranged from 5.0 % to 21.2 % in ambient [CO₂] and from 5.6 % to 21.9 % in elevated [CO₂] without significant differences. Elevated [CO₂] stimulated marked increases in dissolved CO₂ and CH₄ concentrations, and δ¹³C values of CH₄, indicating a positive priming effect of elevated [CO₂] on native SOC decomposition for methanogenesis. In conclusion, elevated [CO₂] did not affect SOC accumulation by simultaneously increasing C input evidenced by increased AGB, and SOC decomposition as CO₂ and CH₄ emissions, hence resulting in a stable SOC quantity in rice paddy ecosystems. Our study delves in the nexus between C input and soil C decomposition under elevated CO₂ condition, highlighting its significance in prediction of the responses of C storage in paddy ecosystems to future climate change.

Keywords: Carbon turnover; Dissolved CH(4); Elevated CO(2); Rice paddy; Stable isotope C.