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Bangor University DOCTOR OF PHILOSOPHY Increasing agricultural grass production using novel bio-inoculants Owen, Darren Award date: 2015 Awarding institution: Bangor University Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Download date: 10. Oct. 2021 Increasing agricultural grass production using novel bio-inoculants A thesis submitted to Bangor University by Darren Wayne Owen In candidature for the degree of Philosophiae Doctor School of Environment, Natural Resources and Geography Bangor Gwynedd LL57 2UW June 2015 SUMMARY Soil micro-organisms are a fundamental component of soil ecosystem services. Plant yields have shown to be increased through processes mediated by fungi, such as increased acquisition of important plant nutrients e.g. phosphate (P) and nitrogen (N). This has seen micro- organisms exploited commercially to create bio-inoculants (BIs). However, it is remarkably difficult to determine the effectiveness of commercially-available BIs that claim to promote crop yields as in most cases the underlying mechanisms responsible for these beneficial effects are unknown. The aims of the thesis were to examine, both within the laboratory and field, the efficacy of some commercially available BIs. Focusing on mechanisms of increased P acquisition mediated by the application of BIs. The effects of soil-P availability on BI performance were also explored. Whilst next generation DNA sequencing was utilised to explore changes in soil fungal assemblages after the introduction of BIs. As illustrated in Chapter 2, there exists much variability in efficacy testing and there is a distinct lack of robust field-based testing of commercial BIs. Chapter 3 consisted of two laboratory-based pot-trials; the first investigated the efficacy of five commercial BIs on Lolium perenne growth, the second explored the effect of an inert carrier media utilised in BI manufacture. Results found that all tested BIs increased grass yields significantly, and while many BIs contain non-living additives, treatments with living microbial fractions were found to have significantly more roots, leading to increased growth per unit P taken up by the grass. The second bioassay found the dual application of carrier media and mycorrhizal spores significantly increased grass yield, the inert carrier media a significant factor with respect to mycorrhizal root colonisation, increasing from 20% to 36%. Chapter 4 explored the phosphate solubilisation and mineralisation potential of the BI products. All BIs successfully mobilised P from recalcitrant P sources (ranging from 164 - 490 mg l-1, for inorganic-P and 0 - 39 mg l-1 for organic-P). A pot trial investigated the phosphorus efficiency ratio of Lolium perenne following application of two inorganic fertilisers of varying solubility, triple super phosphate and rock phosphate. Two of the tested BIs were found to exhibit P mediated growth gains in the form of increased yield, total shoot P, and phosphorous efficiency ratio. Yield and shoot P gains were found to be mediated by differing fractions of the living component of each BI dependent on P source. Chapters 5 and 6 were field trials exploring BI effectiveness on sites of varying P availability. Chapter 5 was on a soil of adequate P (21 mg kg-1). Overall the studies found limited benefits of BI application. Chapter 6 consisted of two field trials, one with a range of P availability (3.3 - 32 mg kg-1), the second with low P availability (8 mg kg-1). Results of the first found positive correlations with the % P and total forage P with increasing plant-available soil-P of BI-treated grass, but no significant increases in yield. The increased P acquisition and lack of yield would suggest that yield limitation was not driven by P. Similarly the results of the second trial found that while some of the BI treated grass yielded moderately higher than controls, there were no significant treatment effects on % P and total forage P, again suggesting yield gains were due to other factors. All BI treatments found to increase the N content of the forage compared to control. Chapter 7 examined the effects of various management practices on soil fungal abundances. Using DNA sequencing, fungal assemblages were found to be significantly affected by both treatment (BI application and N fertiliser), soil type and sampling date. N fertiliser was the only treatment to significantly affect fungal diversity and equitability measures. The study was able to show the potential of NGS technology, Ion Torrent™, for examining changes in fungal communities within the field. The results suggest soils with adequate levels of plant-available P may not see much benefit to warrant the application of BIs, or at least at the application rates recommended. Overall, much work is still required both within science and industry in the development and manufacture of bio-inoculants as a reliable method to increase crop yields. ii ACKNOWLEDGMENTS I would like to thank the following: - My supervisors: Dr. Prysor Williams and Prof. Paul J.A. Withers of Bangor University and Dr. Gareth Griffith of Aberystwyth University. This thesis would not have been possible if not for their tireless support, guidance and expertise. All of their input was, and still is, greatly appreciated - Mark Hughes and Llinos Hughes, Henfaes Research Centre, for all their help and support with the field trials - Dr. Andrew Dethridge for his support, guidance and expertise in all matters related to DNA sequencing - Mr Brian Murcutt and Dr. Penny Dowdney of The Knowledge Economy Skills Scholarships (KESS) European Convergence programme for their support and funding - The European Social Funds (ESF) for their funding - Mr Ian Robertson, Managing Director, and Mr Kevin Ashford, senior agronomist, of the Glenside Group for financial support, resources, expertise and an introduction to an industry I knew little about - Mr Jonathan P. Roberts, Mr Gordon Turner, Ms Sarah Chesworth and Mrs Helen Simpson for their technical support - My many colleagues in the School of Environment, Natural Resources and Geography and the Environment Centre for Wales (2nd floor) - My parents, family and friends for their encouragement and support throughout the project - Lastly, my Fiancé, Layla, who has patiently supported me throughout this period of study providing invaluable encouragement and giving me belief. Love you iii TABLE OF CONTENTS INCREASING AGRICULTURAL GRASS PRODUCTION USING NOVEL BIO- INOCULANTS............................................................................................................... i SUMMARY..................................................................................................................... ii ACKNOWLEDGMENTS.............................................................................................. iii LIST OF FIGURES........................................................................................................ xii LIST OF TABLES.......................................................................................................... xv ACRONYMS................................................................................................................... xix DECLERATION............................................................................................................ xxi CHAPTER 1: INTRODUCTION 1.1. General introduction.............................................................................. 3 1.2. Plan of thesis........................................................................................... 4 1.3. Aims and objectives................................................................................ 5 1.4. References............................................................................................... 5 CHAPTER 2: LITERATURE REVIEW Use of commercial bio-inoculants to increase agricultural production through improved phosphorus acquisition 2.1. Abstract................................................................................................... 9 2.2. Introduction............................................................................................ 10 2.2.1. Phosphorus................................................................................... 10 2.2.2. Phosphate reserves....................................................................... 13 2.2.3. Inorganic fertilisers...................................................................... 14 2.2.4. Fertiliser efficiency....................................................................... 16 2.2.5. Soil phosphorus............................................................................ 17 2.3. Bio-resources........................................................................................... 20 2.3.1. Bio-inoculant composition