Soil organic carbon (SOC) sequestration under elevated CO2 concentration (eCO2 ) is a function of carbon (C) input and C retention. Nitrogen (N) limitation in natural ecosystems can constrain plant responses to eCO2 and their subsequent effects on SOC, but the effect of eCO2 on SOC in N-enriched agroecosystems with cultivars highly responsive to eCO2 is largely unknown. We reported results of SOC dynamics from a field free-air CO2 enrichment experiment with two rice cultivars having distinct photosynthetic capacities under eCO2 . A reciprocal incubation experiment was further conducted to disentangle the effect of changes in litter quality and soil microbial community on litter-derived C dynamics. eCO2 significantly increased total SOC content, dissolved organic C and particulate organic C under the strongly responsive cultivar, likely due to enhanced organic C inputs originated from CO2 stimulation of shoot and root biomass. Increases in the residue C : N ratio and fungal abundance induced by eCO2 under the strongly responsive cultivar reduced C losses from decomposition, possibly through increasing microbial C use efficiency. Our findings suggest that applications of high-yielding cultivars may substantially enhance soil C sequestration in rice paddies under future CO2 scenarios.

中文翻译：

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二氧化碳和水稻品种对稻田土壤碳动态的植物介导作用。

在升高的CO2浓度（eCO2）下隔离土壤有机碳（SOC）是碳（C）输入和碳保留的函数。天然生态系统中的氮（N）限制会限制植物对eCO2的反应及其对SOC的后续影响，但在很大程度上，eCO2对氮素高的农业生态系统中的SOC的影响在栽培品种中对eCO2的响应高度敏感。我们报道了通过在两个自然环境下在eCO2下具有不同光合能力的水稻品种的自由空气CO2富集试验获得的SOC动态结果。进一步进行了相互温育实验，以弄清凋落物质量和土壤微生物群落的变化对源自凋落物的C动态的影响。在强响应品种下，eCO2显着增加了总SOC含量，溶解的有机碳和颗粒状的有机碳，可能是由于CO2刺激芽和根生物量而产生的有机碳输入增加所致。在强响应品种下，eCO2引起的残留碳氮比和真菌丰度的增加减少了分解产生的碳损失，这可能是通过提高微生物的碳利用效率来实现的。我们的研究结果表明，在未来的CO2情景下，高产品种的应用可能会大大增强稻田中的土壤碳固存。