The effects of elevated CO2 and temperature on soil organic carbon and total nitrogen contents and mineralization in the 0 to 50 cm paddy soil layer were masked by different land use history
Shuirong Tang,
Weiguo Cheng,
Samuel Munyaka Kimani,
Keitaro Tawaraya,
Takeshi Tokida,
Mayumi Yoshimoto,
Hidemitsu Sakai,
Yasuhiro Usui,
Hirofumi Nakamura,
Miwa Y. Matsushima,
Xingkai Xu,
Toshihiro Hasegawa
Affiliations
Shuirong Tang
United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan; School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572025, PR China; Faculty of Agriculture, Yamagata University, 1-23, Wakaba-machi, Tsuruoka, Yamagata 997-8555, Japan
Weiguo Cheng
United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan; Faculty of Agriculture, Yamagata University, 1-23, Wakaba-machi, Tsuruoka, Yamagata 997-8555, Japan; Corresponding author at: Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata 997-8555, Japan.
Samuel Munyaka Kimani
United Graduate School of Agricultural Sciences, Iwate University, 3-18-8 Ueda, Morioka, Iwate 020-8550, Japan; Institute for Agro-Environmental Sciences, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan
Keitaro Tawaraya
Faculty of Agriculture, Yamagata University, 1-23, Wakaba-machi, Tsuruoka, Yamagata 997-8555, Japan
Takeshi Tokida
Institute for Agro-Environmental Sciences, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan; Advanced Analysis Center, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan
Mayumi Yoshimoto
Institute for Agro-Environmental Sciences, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan
Hidemitsu Sakai
Institute for Agro-Environmental Sciences, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan
Yasuhiro Usui
Central Region Agricultural Research Center, NARO, 2-1-18 Kannondai, Tsukuba, Ibaraki 305-8666, Japan
Hirofumi Nakamura
Taiyokeiki Co. Ltd, Kita-Ku, Tokyo 114-0032, Japan
Miwa Y. Matsushima
Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, Chiba 271- 8510, Japan
Xingkai Xu
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, PR China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, PR China
Toshihiro Hasegawa
Institute for Agro-Environmental Sciences, NARO, 3-1-3, Kannondai, Tsukuba, Ibaraki 305-8604, Japan
Global warming can accelerate soil organic matter (SOM) decomposition resulting in faster carbon (C) loss and positive climate-C feedback. Previous studies on response of SOM decomposition to climate change mainly focus on plow soil layer. However, the effects of elevated CO2 and soil warming on soil organic carbon (SOC) and total nitrogen (TN) contents and mineralization are rarely studied in subsoil layer. In this study, soil samples were collected from the 0–50-cm paddy soil layer of the Tsukuba free-air CO2 enrichment experimental site with elevated CO2 (+200 ppm) and soil warming (+2 °C), Japan, after 5-year rice growth season. The amounts of SOC, TN, δ13C, and δ15N were analyzed. A 4-week anaerobic incubation experiment was conducted to measure C decomposition and N mineralization potentials. Due to the intrinsic variation in SOC and TN contents in soil layers and fields, the effects of elevated CO2 and soil warming on C decomposition and N mineralization potentials could not be determined here. However, the effect of elevated CO2 on δ13C was only found in 0‒10-cm soil layer. In the 0–50-cm soil profiles, significant correlations were observed among SOC and TN, δ13C and δ15N, decomposed C and mineralized N, and δ13C of decomposed C. The variables associated with soil C and N pools, and dynamics showed large spatial heterogeneity within paddy field, due to variation in the original land use history. Therefore, great caution should be exercised when evaluating the effects of elevated CO2 and temperature on SOM decomposition and sequestration in paddy soil profiles.
