Overview
The report provides a detailed assessment of the distribution of soil fungi and bacteria species across four Australian wine regions: the Barossa Valley, McLaren Vale, Sunraysia and the Yarra Valley. More recent research extends the knowledge and management techniques described here. At the time, DNA-based sequencing showed fungal and bacterial community composition differed significantly by region and by vineyard location (undervine, midrow and native vegetation), driven mainly by soil pH, organic carbon and nitrogen. A detailed case study linked distinct soil bacterial communities to vine vigour and wine quality zones within one vineyard, consistent with a microbial terroir concept not yet fully understood.
Perhaps the most exciting prospect to emerge from this research is the establishment of the relationship between soil microbial communities, vine vigour and wine quality. This research has demonstrated the strong influence of region, location and vine vigour on specific groups of microbes. The significance of these relationships is yet to be fully elucidated but it is entirely possible that signature communities in soil will have a direct relationship on wine quality (i.e. ‘microbial terroir’). Knowledge of the chemical factors that influence or drive this relationship provides the means for manipulating these microbial communities to achieve the desired wine quality outcome.
Some challenges remain in terms of both sampling regimes and commercial availability of tests. Microbial communities are dynamic and therefore sensitive to sample handling. Stringency and standardised sampling regimes are required to preserve the integrity of the microbial communities at the point of sampling. Unfortunately the consequence of less stringency in sampling was seen for the SA wine growing regions where a significant number of samples did not yield sufficient high quality DNA to be useful for subsequent sequencing protocols. In terms of availability of testing facilities, even the standard biological tests chosen for the MDS proved to be difficult to get from commercial laboratories (refer to DPI1101). Labile carbon, potentially mineralisable nitrogen (PMN) and microbial biomass analyses are generally available on a semi-commercial basis only. For the more sophisticated tests, an existing DNA based testing platform, SARDI’s PreDicta B platform could be utilised as is the case for the Grains industry soil quality monitoring program. An added advantage is access to a whole range of new measures of soil biota.
Abstract
This project evaluated the potential application of more precise measures of soil microbiology as a component of a wider soil health monitoring program developed by AGWA project ‘Setting benchmarks and recommendations for management of soil health in Australian viticulture’ (DPI1101). These new DNA based measures have provided unprecedented insights into the composition and function of microbial communities in vineyard soils of four wine growing regions; the Barossa Valley, McLaren Vale, Sunraysia and the Yarra Valley. This project has identified key relationships between these microbial and prevailing soil chemical features and to a lesser extent, vine performance parameters. It provides recommendations on the types of measures that could be integrated into existing minimum data sets as well and on a web based repository for capturing and interpreting this data as part of a long term, monitoring program.
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Categories
Soil health
Vineyard management
Sustainability & Climate
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