Abstract. The active fraction of soil organic carbon (SOC) is an important component of soil health and often is quickly assessed as the amount of CO₂ released by re-wetting dried soils in short-term (24–72 h) assays. However, soils can lose carbon (C) as they dry and if soil samples vary in moisture content at sampling, differential C loss during the pre-assay dry-down period may complicate interpretations of C availability. We examined pre-assay CO₂ loss and its influence on apparent C availability in the same soil at initial moisture contents of 30, 50, and 70 % water-filled pore space (WFPS). We found that 50 and 70 % WFPS treatments lost more C during drying than those in the 30 % WFPS treatment, which led to a 26–32 % underestimate of C availability in wetter soil. We developed a soil-specific correction factor to account for these initial soil moisture effects. Future C mineralization studies may benefit from similar corrections.

中文翻译：

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短期交流：量化和校正短期碳矿化测定中的测定前CO ₂损失

摘要。土壤有机碳（SOC）的活性成分是土壤健康的重要组成部分，通常在短期（24-72小时）测定中通过将干土壤重新湿润而迅速评估为释放的CO ₂量。但是，土壤在干燥过程中可能会损失碳（C），如果土壤样品在采样时含水量发生变化，则在分析前的干燥期中不同的C损失可能会使C可用性的解释变得复杂。我们检查了测定前CO ₂初始水分含量为30％，50％和70％的充水孔隙空间（WFPS）时，相同土壤中的氮素损失及其对表观C有效性的影响。我们发现，在干燥过程中，50％和70％WFPS处理比30％WFPS处理损失更多的碳，这导致湿土壤中C的有效性低估了26–32％。我们开发了特定于土壤的校正因子，以解决这些最初的土壤水分影响。未来的C矿化研究可能会受益于类似的修正。