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 small, with 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.
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 small, with 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.
| Original language | English |
|---|---|
| Pages (from-to) | 369-389 |
| Number of pages | 21 |
| Journal | Plant and Soil |
| Volume | 480 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - 28 Jul 2022 |
Bibliographical note
Funding Information:The authors wish to thank the NERC for partial funding of the National Environmental Isotope Facility (NEIF; contract no. NE/V003917/1) and the HEFCE SRIF and the University of Bristol for funding the GC-IRMS capabilities. Rothamsted Research are thanked for providing soils from the North Wyke Farm Platform for incubation experiments, and Liz Dixon at North Wyke is thanked for support with N analyses of soil and plant biomass. 15
Funding Information:
This work was conducted as part of K. Pears’ PhD studies at University of Bristol funded through the SWBio DTP BBSRC. Compound-specific N-analyses were conducted at the National Environmental Isotope Facility Bristol laboratory (NEIF-B) at University of Bristol (NE/S011587/1). 15
Publisher Copyright:
© 2022, The Author(s).
Research Groups and Themes
- Organic & Biological
Keywords
- Nitrogen transfer
- Clover
- 15N-stable isotope probing
- Soil microbial community