Warming offsets the beneficial effect of elevated CO2 on maize plant-carbon accumulation in particulate organic carbon pools in a Mollisol
2022
Fang, Rui | Li, Yansheng | Yu, Zhenhua | Xie, Zhihuang | Wang, Guanghua | Liu, Xiaobing | Herbert, Stephen J. | Jin, Jian
Investigating the interactive effect of elevated CO₂ and warming on photosynthetic carbon (C) detained in soil organic C (SOC) fractions is pivotal to predict the SOC stability in farming soils in response to climate change, especially in a major maize-grown Mollisol, one of most fertile farming soil in the world. Using open top growth chamber (OTC) to mimic the rises of atmospheric CO₂ concentration up to 550 ppm and temperature 2 °C above surroundings, one set of maize plants were labelled with ¹³CO₂ across the first growth season, and the other set of plants were grown in OTCs for four seasons. We found that elevated CO₂ increased plant-C in the fine particulate organic C fraction from 0.53 mg kg⁻¹ under the control to 0.89 mg kg⁻¹, while warming plus elevated CO₂ did not alter plant-C allocation into this fraction. Elevated CO₂ increased plant-C accumulated in the mineral-associated C (MOC) fraction, but not C content in this fraction. There was no change of C content in the MOC fraction with plant grown under climatic conditions over time. Climate change may not alter SOC stock but accelerate the fresh-old-C exchange in maize-grown Mollisols as warming may accelerate turnover of plant-derived C.
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