欢迎访问PEDOSPHERE网站！

Pedosphere 23(6): 752--766, 2013
ISSN 1002-0160/CN 32-1315/P
©2013 Soil Science Society of China
Published by Elsevier B.V. and Science Press

Effect of atmospheric CO₂ enrichment on soil respiration in winter wheat growing seasons of a rice-wheat rotation system

SUN Hui-Feng^1,2, ZHU Jian-Guo¹

, XIE Zu-Bin¹, LIU Gang^1,3 and TANG Hao-Ye¹

¹State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)
²University of Chinese Academy of Sciences, Beijing 100049 (China)
³Jiangsu Biochar Engineering Center, Nanjing 210008 (China)

ABSTRACT

Studies on the effect of elevated CO₂ on C dynamics in cultivated croplands are critical to a better understanding of the C cycling in response to climate change in agroecosystems. To evaluate the effects of elevated CO₂ and different N fertilizer application levels on soil respiration, winter wheat (Triticum aestivum L. cv. Yangmai 14) plants were exposed to either ambient CO₂ or elevated CO₂ (ambient [CO₂] + 200 μmol mol^-1), under N fertilizer application levels of 112.5 and 225 kg N ha^-1 (as low N and normal N subtreatments, respectively), for two growing seasons (2006–2007 and 2007–2008) in a rice-winter wheat rotation system typical in China. A split-plot design was adopted. A root exclusion method was used to partition soil respiration (RS) into heterotrophic respiration (RH) and autotrophic respiration (RA). Atmospheric CO₂ enrichment increased seasonal cumulative RS by 11.8% at low N and 5.6% at normal N when averaged over two growing seasons. Elevated CO₂ significantly enhanced (P < 0.05) RS (12.7%), mainly due to the increase in RH (caused by decomposition of larger amounts of rice residue under elevated CO₂) during a relative dry season in 2007–2008. Higher N supply also enhanced RS under ambient and elevated CO₂. In the 2007–2008 season, normal N treatment had a significant positive effect (P < 0.01) on seasonal cumulative RS relative to low N treatment when averaged across CO₂ levels (16.3%). A significant increase in RA was mainly responsible for the enhanced RS under higher N supply. The correlation (r²) between RH and soil temperature was stronger (P < 0.001) than that between RS and soil temperature when averaged across all treatments in both seasons. Seasonal patterns of RA may be more closely related to the plant phenology than soil temperature. The Q₁₀ (the multiplier to the respiration rate for a 10 °C increase in soil temperature) values of RS and RH were not affected by elevated CO₂ or higher N supply. These results mainly suggested that the increase in RS at elevated CO₂ depended on the input of rice residue, and the increase in RS at higher N supply was due to stimulated root growth and concomitant increase in RA during the wheat growing portion of a rice-winter wheat rotation system.

Key Words: autotrophic respiration, carbon dynamics, heterotrophic respiration, N fertilization, soil temperature

Citation: Sun, H. F., Zhu, J. G., Xie, Z. B., Liu, G. and Tang, H. Y. 2013. Effect of atmospheric CO₂ enrichment on soil respiration in winter wheat growing seasons of a rice-wheat rotation system. Pedosphere. 23(6): 752-766.

View Full Text