Abstract Estimates of nitrogen (N) losses from living plants (phyllo- and rhizodeposition) are needed to improve the sustainability of the present agricultural cropping systems. These estimates are hard to achieve under field conditions among others due to a lack of suitable methods to study these N flows. A novel vertical split-root with 15N placement in deeper soils layers is suggested here as a means to improve the present tracer based methods for phyllo- and rhizodeposition estimation. We found enrichment of soil above the point of tracer injection (at 290 cm) with rhizosphere having higher enrichment than bulk soil underlining that 15N was derived from roots. The relative net N rhizodeposition was highest for lucerne and decreased with depth for all three plant species investigated (lucerne, kernza®, rosinweed). The quantity of N lost via rhizodeposition amounted to 10–13 kg N ha−1 in the topsoil, but the majority of the N rhizodeposition was found below (25–250 cm) showing the importance of including deeper soil layers in such studies.

中文翻译：

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一种新的 15N 垂直分根法原位估计 N 根际沉积

摘要 需要对活植物（叶状和根际沉积）的氮 (N) 损失进行估算，以提高当前农业种植系统的可持续性。由于缺乏合适的方法来研究这些 N 流，这些估计在现场条件下很难实现。这里建议采用一种在较深土壤层中放置 15N 的新型垂直分根，作为改进目前基于示踪剂的叶状和根际沉积估计方法的一种手段。我们发现在示踪剂注入点（290 厘米）以上的土壤富集，根际富集比大块土壤高，强调 15N 来自根。苜蓿的相对净氮根沉积量最高，并随着研究的所有三种植物物种（苜蓿、kernza®、松香）的深度而降低。