Warming and elevated CO₂ interactively affect the photosynthetic carbon of maize plant retained in major farming soils

Warming and elevated CO₂ (eCO₂) may influence the input of photosynthetic carbon (C) into soils and subsequent soil C storage. The biochemical properties vary among soils, which likely act different roles in the fate of photosynthetic C and soil C sequestration in response to warming and eCO₂. However, the interactive effects of climate change and soil types on the photosynthetic C retained in soil and relevant mechanisms are poorly understood. We performed a pot experiment in open-top chambers to examine the effects of eCO₂ (550 ppm) combined with elevated temperature (eT, 2 °C higher than the air temperature) on the retention of plant-C of maize (Zea mays L.) grown in Phaeozem, Fluvisol, Kastanozem and Acrisol with ¹³CO₂ labeling at the silking stage. The proportion of ¹³C to the total fixed ¹³C increased by 44.6%, 96.1% and 41.9% in Phaeozem under eT, eCO₂ and eT plus eCO₂ treatments compared with control, while decreased in other three soils in response to either eCO₂, eT or eT plus eCO₂. The effect of climate change on fresh C input in maize cropping soils depended on soil type, and soil net C losses may occur in the Fluvisol, Kastanozem and Acrisol under climate change.

Abbreviations: eCO₂: elevated CO₂, 550ppm; eT: warming; aCO₂: ambient CO₂, 400ppm; aT: ambient temperature; OTC: open-top chamber; DOC: dissolved organic carbon; SOC: soil organic carbon; C: carbon; S: soil; T: temperature.