Roots can add significant amounts of carbon (C) to the subsoil, which improves soil physical properties and can mitigate climate change. About 5% of croplands in Germany have been deep-ploughed (30–120 cm) at least once. This can provide better root access to the subsoil and may increase yields, but little is known on the fate of root-derived C in the subsoil (at depth greater than 30 cm) after deep-ploughing. We hypothesized that five decades after deep-ploughing, root-derived C stocks were higher than conventionally ploughed treatments due to better root development. We analysed suberin and cutin monomers as tracers for root- and shoot-derived C at three former deep-ploughed sites in Northern Germany with different soil textures and deep-ploughing depths. Concentrations of suberin monomers in the soil positively correlated with root biomass; this was most pronounced at one sandy site, but had higher variability at the other two sites due to crops with different root systems in the crop rotation, lower root development, and more favourable conditions for C decomposition. Suberin contributed more to the bulk soil organic carbon (SOC) stocks than cutin throughout the soil profile at all sites. The contribution of suberin monomers to the bulk SOC stock at silty site Banteln and the sandy site Essemühle was 38% higher in the deep-ploughed plots than at the reference plot, respectively, these differences were most visible in the subsoil of Essemühle. We conclude that as C stocks and root development increase, suberin SOC stocks also increase, especially in sandy subsoils with low pH.

中文翻译：

---

以前深耕土壤中根部衍生的碳储量——基于生物标记的方法

根部可以向底土添加大量碳 (C)，从而改善土壤物理特性并缓解气候变化。德国约 5% 的农田至少深耕过一次（30-120 厘米）。这可以使根部更好地进入底土，并可能提高产量，但深耕后根部来源的碳在底土（深度大于 30 厘米）中的去向知之甚少。我们假设深耕五年后，由于根部发育更好，根部来源的碳储量高于传统翻耕处理。我们在德国北部的三个前深耕地点（具有不同的土壤质地和深耕深度）分析了木栓质和角质单体，作为根和茎衍生碳的示踪剂。土壤中木栓质单体的浓度与根系生物量呈正相关；这种现象在一个沙地最为明显，但由于轮作中作物根系不同、根系发育较低以及碳分解条件更有利，因此其他两个地点的变异性较高。在所有地点的土壤剖面中，木栓质对土壤有机碳 (SOC) 库的贡献大于角质。在深耕地块中，Banteln 粉质地点和 Essemühle 沙质地点的木栓质单体对大量 SOC 储量的贡献分别比参考地块高 38%，这些差异在 Essemühle 的底土中最为明显。我们得出的结论是，随着碳储量和根系发育的增加，木栓质 SOC 储量也会增加，特别是在 pH 值较低的沙质底土中。