Long-term field experiments have confirmed belowground plant carbon (C) to be two to three times more efficient precursor of soil organic carbon (SOC) than aboveground plant residues. But it remains elusive just when this belowground biomass is relatively stabilized against mineralization: during the initial fast degradation, or on the longer term? A one-year field experiment was set up with biweekly follow-up of the in-situ mineralization of maize (Zea mays L.) C-inputs, either above- or belowground biomass based on soil δ¹³C resolved CO₂ emissions. In addition, a treatment with maize roots and post-harvest remnant rhizodeposited-C left undisturbed in the field was included as well as a corresponding control that was physically disturbance as in the other treatments. We found that most maize-C was mineralized within a year with peaks in late fall and spring, i.e. 1 and 8 months after incorporation. Shoot-C decomposed only 1.4 times faster than root-C though statistically insignificant, which shows that on the short term (i.e. within a single year) the 2–3 fold stability of belowground biomass C is not manifested. Total maize-derived CO₂ emissions of soil amended with only roots and with roots and post-harvest rhizodeposits were equal, likely because the rhizodeposited-C had already degraded quickly. A much smaller share of root- and rhizodeposited-C (43%) was mineralized when soil was not disturbed after harvest. We hypothesize that such a delayed physical disturbance, which in practice would only occur in early spring, could be key in stabilizing belowground biomass C in the field. Overall, our findings show a limited difference in degradability of roots and shoots under field conditions on the short term, and a large effect of tillage timing.

长期的野外试验已经证实，地下植物碳（C）的效率是土壤有机碳（SOC）前体的效率是地下植物残渣的2至3倍。但是，当这种地下生物量相对稳定以防止矿化时，它仍然难以捉摸：在最初的快速降解过程中，还是从长期来看？进行了为期一年的田间试验，每两周跟踪一次 玉米 ( Zea mays L.) C 输入的原位矿化，基于土壤δ ¹³ C 解析 CO _{2 的}地上或地下生物量排放。此外，还包括在田间不受干扰的玉米根和收获后残留根茎-C 的处理，以及与其他处理一样受到物理干扰的相应对照。我们发现大多数玉米-C 在一年内矿化，峰值出现在晚秋和春季，即掺入后的 1 个月和 8 个月。尽管统计上不显着，但地上部碳分解速度仅比根碳分解快 1.4 倍，这表明在短期内（即在一年内）地下生物量碳的 2-3 倍稳定性并未表现出来。总玉米衍生的 CO ₂仅用根和用根和收获后的根际沉积物修正的土壤排放量相等，可能是因为根际沉积物-C 已经迅速降解。当收获后土壤没有受到干扰时，很少一部分根和根系沉积的碳 (43%) 被矿化。我们假设这种延迟的物理干扰（实际上只会在早春发生）可能是稳定田间地下生物量C的关键。总体而言，我们的研究结果表明，短期内在田间条件下根和芽的降解能力差异有限，耕作时间的影响很大。