The growth of deep-rooted crops has the potential to increase carbon deposition within deep subsoil layers, thereby contributing to climate change mitigation. Yet, the mechanisms of labile carbon stabilization in deep subsoils remain uncertain. Here we studied the effect of nitrogen, phosphorus and sulphur limitations on the microbial mineralization of added glucose and an artificial root exudate mixture (both spiked with ¹⁴C-glucose) in intact soil samples from a deep subsoil (5–6 m) over a 10-week incubation period, where the temporal respiration of CO₂ and ¹⁴CO₂ were quantified. We found that mineralization was co-limited by nitrogen and phosphorus, but the cumulative amount of CO₂ emitted was significantly larger from artificial root exudates than glucose, suggesting that the nitrogen carried in amino acids in root exudates (here, L-arginine) was sufficient to overcome the nitrogen limitation in this subsoil.

中文翻译：

---

氮磷共限对深层底土不稳定碳矿化

深根作物的生长有可能增加深层土壤中的碳沉积，从而有助于减缓气候变化。然而，深层底土中不稳定碳稳定的机制仍然不确定。在这里，我们研究了氮、磷和硫限制对来自深层底土（5-6 m）的完整土壤样品中添加的葡萄糖和人工根系分泌物混合物（均掺入¹⁴ C-葡萄糖）的微生物矿化的影响。10 周潜伏期，其中 CO ₂和¹⁴ CO ₂的时间呼吸被量化。我们发现矿化受氮和磷的共同限制，但 CO ₂的累积量 人工根系分泌物的排放量明显大于葡萄糖，这表明根系分泌物（此处为 L-精氨酸）中氨基酸携带的氮足以克服该底土中的氮限制。