Optimising Vineyard Floor Management Across Australian Viticultural Landscapes to Enahnce Functional Plant Diversity and Soil Health
Date
2023
Authors
Kesser, Merek Marie
Editors
Advisors
Collins, Cassandra
De Bei, Roberta (Plant and Food Research Australia)
Cavagnaro, Timothy (Flinders University)
De Bei, Roberta (Plant and Food Research Australia)
Cavagnaro, Timothy (Flinders University)
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Thesis
Citation
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Abstract
Intensive vineyard floor management practices such as tillage and herbicides to control unwanted vegetation are being increasingly replaced by less-intensive strategies that improve biodiversity and provide ecosystem services. This thesis investigated vineyard floor management in the Australian context to present insights to environment and production related outcomes associated with different vineyard floor management approaches. To start, plant species dynamics and soil properties were assessed seasonally at twenty-four vineyard sites and four native areas over one growing season. Results from this work suggested that ruderal weed species were decreased with less intensive vineyard floor management, particularly when no herbicides or tillage was applied to under-vine areas. Soil water infiltration was significantly greater in the under-vine areas where low intensity management was practiced, as was overall plant coverage and species richness. The under-vine areas were assessed in more detail at a subsequent study carried out at two long-term commercial trials in Eden Valley and McLaren Vale, where spontaneous vegetation was maintained in one treatment, while herbicides (Eden Valley) or tillage (McLaren Vale) were carried out in adjacent treatment blocks. Spontaneous vegetation treatments provided more consistent soil coverage, reduced coverage by ruderal weed species in the Asteraceae (thistles) family, and improved water infiltration in McLaren Vale. There were no significant impacts on yields at the two sites, however, there were reduced pruning weights and vegetative growth at Eden Valley, a site with loamy sand soils. To further investigate the vineyard floor management strategies used in a wider Australian context, a national survey was conducted from which 199 responses were collected. Vineyards that did not use chemical weed control were smaller in size, rated their soil management as more sustainable, and rated their biodiversity higher compared to vineyards that did use herbicides. To enhance terroir expression was a motivation correlated with not using herbicides, and this finding initiated research of the contribution of floor management to soil terroir factors. The exploration of soil microbiomes to contribute to terroir factors was carried out at twenty-four vineyards in six sub-regions of the Barossa. The structure of the bacterial community was most significantly correlated with soil pH, plant-available (Colwell) phosphorus, % clay, and sub-region; while the structure of the fungal community was most driven by soil phosphorus, % clay, pH, and latitude. Soil microbial communities and physiochemical properties differentiated the Eden Valley sub-region from the other five sub-regions, while under-vine floor management practices did not have clear effects on the microbial communities. A final chapter on the impact of bushfire in the Adelaide Hills on soil properties, soil microbiomes, and plant species at four commercial vineyards. There were not significant impacts on soil microbial diversity, although the evenness of both bacteria and fungi was lower with increasing burn severity. At one vineyard, there was higher plant biomass and plant coverage by species in the Asteraceae family, providing insights to vineyard managers of management implications post-bushfire.
School/Discipline
School of Agriculture, Food and Wine
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2023
Provenance
This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals