Aims Mineral-associated organic matter, mainly derived from microbial by-products, persists longer in soil compared to particulate organic matter (POM). POM is highly recalcitrant and originates largely from decomposing root and shoot litter. Theory suggests that root traits and growth dynamics should affect carbon (C) accumulation into these different pools, but the specific traits driving this accumulation are not clearly identified. Methods Twelve herbaceous species were grown for 37 weeks in monocultures. Root elongation rate (RER) was measured throughout the experiment. At the end of the experiment, we determined morphological and chemical root traits, as well as substrate induced respiration (SIR) as a proxy for microbial activity. Carbon was measured in four different soil fractions, following particle-size and density fractionation. Results Root biomass, RER, root diameter, hemicellulose content and SIR (characteristic of N 2 -fixing Fabaceae species), were all positively correlated with increased C in the coarse silt fraction. Root diameter and hemicellulose content were negatively correlated with C in the POM fraction, that was greater under non N 2 -fixing Poaceae species, characterized by lignin-rich roots with a high carbon:nitrogen ratio that grew slowly. The accumulation of C in different soil pools was mediated by microbial activity. Conclusions Our results show that root traits determine C input into different soil pools, mediated primarily by microbial activity, thus determining the fate of soil organic C. We also highlight that C in different soil pools, and not only total soil organic C, should be reported in future studies to better understand its origin, fate and dynamics.

中文翻译：

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持久性途径：植物根系特征改变不同土壤碳库中的碳积累

与颗粒有机物 (POM) 相比，主要来自微生物副产品的矿物相关有机物在土壤中的存留时间更长。POM 具有很强的顽固性，主要源于分解根和枝条凋落物。理论表明，根性状和生长动态应影响这些不同库中的碳 (C) 积累，但尚未明确确定驱动这种积累的具体特征。方法 12 种草本植物在单一栽培中生长 37 周。在整个实验过程中测量根伸长率 (RER)。在实验结束时，我们确定了形态和化学根特征，以及作为微生物活动代理的底物诱导呼吸 (SIR)。根据颗粒大小和密度分级，在四种不同的土壤组分中测量碳。结果 根生物量、RER、根直径、半纤维素含量和 SIR（固定 N 2 豆科植物的特征）都与粗粉粒部分中 C 的增加呈正相关。根直径和半纤维素含量与 POM 部分中的 C 呈负相关，在非固氮禾本科物种下 C 更大，其特征在于富含木质素的根，具有高碳氮比，生长缓慢。C在不同土壤池中的积累是由微生物活动介导的。结论 我们的结果表明，根系性状决定了进入不同土壤池的 C 输入，主要由微生物活动介导，从而决定了土壤有机 C 的命运。我们还强调，不同土壤池中的 C，而不仅仅是土壤总有机 C，应该是在未来的研究中报告以更好地了解其起源，