Mechanisms of nitrogen transfer in a model clover‑ryegrass pasture a 15N‑tracer approach

A - Papers appearing in refereed journals

Reay, M. K., Pears, K. A., Kuhl, A., Evershed, R. P., Murray, P. J., Cardenas, L. M., Dungait, J. A. J. and Bull, I. D. 2022. Mechanisms of nitrogen transfer in a model clover‑ryegrass pasture a 15N‑tracer approach. Plant and Soil. https://doi.org/10.1007/s11104-022-05585-0

AuthorsReay, M. K., Pears, K. A., Kuhl, A., Evershed, R. P., Murray, P. J., Cardenas, L. M., Dungait, J. A. J. and Bull, I. D.
Abstract

Purpose
Nitrogen (N) transfer from white clover (Trifolium repens cv.) to ryegrass (Lolium perenne cv.) has the potential to meet ryegrass N requirements. This study aimed to quantify N transfer in a mixed pasture and investigate the influence of the microbial community and land management on N transfer.
Methods
Split root 15N-labelling of clover quantified N transfer to ryegrass via exudation, microbial assimilation, decomposition, defoliation and soil biota. Incorporation into the microbial protein pool was determined using compound-specific 15N-stable isotope probing approaches.
Results
N transfer to ryegrass and soil microbial protein in the model system was relatively smallwith one-third arising from root exudation. N transfer to ryegrass increased with no microbial competition but soil microbes also increased N transfer via shoot decomposition. Addition of mycorrhizal fungi did not alter N transfer, due to the source-sink nature of this pathway, whilst weevil grazing on roots decreased
microbial N transfer. N transfer was bidirectional, and
comparable on a short-term scale.
Conclusions
N transfer was low in a model young pasture established from soil from a permanent grassland with long-term N fertilisation. Root exudation and decomposition were major N transfer pathways. N transfer was influenced by soil biota (weevils, mycorrhizae) and land management (e.g. grazing). Previous land management and the role of the microbial community in N transfer must be considered when determining the potential for N transfer to ryegrass

KeywordsNitrogen transfer ; CLover; 15N-stable isotope probing; Soil microbial community
Year of Publication2022
JournalPlant and Soil
Digital Object Identifier (DOI)https://doi.org/10.1007/s11104-022-05585-0
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Natural Environment Research Council
Funder project or codeSWBio DTP PhD studentship
NE/S011587/1
Publisher's version
Output statusPublished
Publication dates
Online28 Jul 2022
Publication process dates
Accepted25 Jun 2022
PublisherSpringer
ISSN0032-079X

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