Fostering populations of arbuscular mycorrhizal fungi (AMF) through cover crop choices and soil management (PhD)

Summary

Over 70% of land plants form a beneficial, symbiotic relationship with arbuscular mycorrhizal (AM) fungi, including many key agricultural crops. This has triggered interest in the potential role of these fungi in sustainable food production.

However, many common farming practices can negatively influence – both the diversity and abundance – of AM fungi. It is desirable to identify farming practices that could foster these fungal populations to increase crop (including yield) and soil benefits.

Cover cropping (cultivation of crops or crop mixtures, usually during winter months) is used to protect and improve soil. The practice potentially contributes to ecosystem services, including enhancing the diversity and abundance of AM fungi.

This study aimed to determine the impact of cover cropping and other amendments (including mycorrhizal inoculum, and various forms of nitrogen) on the diversity and abundance of AM fungi and, critically, the resulting impact on crop yield and quality.

A large-scale analysis of AM fungal diversity in UK agriculture, in collaboration with FERA, provided a framework for further analysis of how cover crops and soil amendments influence AM fungal communities. In total, 84 AM fungal virtual taxa were identified from across the 67 independent sites in the trial.

Building on this baseline understanding, results from replicated field trials provided evidence that multiple iterations of cover crops can increase the extent to which plants are colonised by AM fungi, but single iterations had no measurable impact.

In the New Farming Systems: Fertility Building Rotations trial, it was shown that repeated applications of nitrogen fertiliser over several years influenced AM fungal community composition. However, this observation was not made in a shorter field-scale validation experiment that used AD (digestate from anaerobic digestion) as the nitrogen source. In this trial, there was no link between increased diversity or abundance of AM fungi, and increased crop growth or yield.

In another trial (Bawburgh, Norfolk), addition of a commercial AM fungal inoculum had little impact on the AM fungal community, crop growth, or yield in field conditions. This further suggests that multiple iterations of soil amendments are required to cause measurable, long-term shifts in AM fungal diversity and other soil benefits.

Finally, results from field-scale experimentation provided evidence that cover crops or AM fungal inoculum could positively influence AM fungal abundance or diversity and improve crop yield. However, cover crops were found to assimilate soil nitrogen, following autumn applications, especially from deeper soil horizons, which may reduce environmental impact, such as diffuse pollution resulting from application of nitrogen-based fertiliser.

Final report

The final report for this project will be released following the publication of related in-press scientific papers.

Also..

Sector:
Cereals & Oilseeds
Project code:
SR54
Date:
01 January 2018 - 31 December 2021
Funders:
AgriFood Charities Partnership funding
AHDB sector cost:
£45,250
Total project value:
£70,250
Project leader:
University of Cambridge (Scientific partner: NIAB. Industry partner: PlantWorks).

Downloads

21140024 Annual Project Report (2019) 21140024 Annual Project Report (2020) 21140024 Annual Project Report (2021)
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