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A novel 15N vertical split-root method for in situ estimation of N rhizodeposition

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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.

Antal sider5
StatusUdgivet - feb. 2021

Bibliografisk note

Funding Information:
We thank Jørgen Olesen and Lars Elsgaard for discussions, Karin Dyrberg and Bodil Stensgaard for technical assistance, and Kristian Thorup-Kristensen for providing access to the RootTower facility. This work was performed as part of the Deep Frontier project, which is a research collaboration between University of Copenhagen, Aarhus University and International Centre for Research in Organic Food Systems (ICROFS), financed by the Villum Foundation. Kirsten Lønne Enggrob and Jim Rasmussen was further supported by the “Stable or fertile” project funded by the Danish Independent Research Fund (project no. 9041-00132A).

Publisher Copyright:
© 2020 Elsevier B.V.

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