Key points
- Innovative technologies are needed to monitor and manage soil and water resources to ensure environmental and financial sustainability of the Australian grape and wine sector.
- In-field, low cost rapid analytical tools are being developed by the AWRI to support decision making processes.
- The use of such tools will vary depending on the unique requirements of Australia’s diverse regions.
- A portable ‘backpack’ style instrument is one such tool that can be used to determine characteristics of soil and also vine water requirements with important implications for efficient water use.
- The economic benefits of understanding better the whole ecosystem will result in an Australian grape and wine sector that will not just survive, but advance and thrive.
Background
Modern technological developments in positioning, sensing, and control systems have opened a new era in which many traditional agricultural practices are being left behind. Replacing them are ‘precision farming’ techniques in viticulture that manage variability within a field by applying agronomic inputs in the right place, at the right time, and in the right quantity to reduce the environmental impact of modern grape and wine production.
For example, soil carbon pool measurements which are needed to study carbon sequestration and measurements of soil nitrogen could be used to manage and minimise the leaching of nitrates into the ground water. Research has been initiated on the use of in-field sensors based on visible and near infrared (Vis-NIR) spectroscopy to enable the rapid and non-destructive analysis of chemical and physical properties of soil and plant components in the vineyard. A portable ‘backpack’ style instrument is one such tool being developed by the AWRI and its WIC partners. This instrument can be used to determine characteristics of soil and also vine water requirements in the field, with important implications for real time decision-making about efficient water use.
In the near infrared (NIR) region, several wavelengths (e.g. 950 nm, 1400 nm and 1900 nm) are strongly influenced by the presence of water and the particular state of water in the measured sample. A collaborative study is now underway between the AWRI, SARDI, The University of Adelaide and CSIRO to integrate different methods to assess and manage water in the vineyard. In particular, the AWRI is developing a NIR method combined with multivariate analysis that will relate NIR absorption spectra with physiological measures of leaf water status measured in field grown Shiraz, Cabernet Sauvignon and Chardonnay grapevines. In this preliminary study, leaf samples were taken from different treatments and analysed using a portable Vis-NIR instrument (800 1800 nm) in reflectance. Partial least square (PLS) calibrations between reference and NIR data were developed using cross validation. Preliminary NIR calibrations yielded good correlation coefficients between predicted and measured stem and leaf water potential (r > 0.60, Figure 1). These functions appear to hold within a variety for several weeks of measurement. It is also possible to determine clear trends in the spectra that would allow a rapid detection of the onset of water stress. This new development will allow irrigation to be more closely tailored to vine requirements, providing greater control, improved sustainability and reduced environmental impact.
For more information contact Dr Daniel Cozzolino (Senior Research Scientist, Rapid Analytical Methods) by phone: 83036600 or email: sustainability@awri.com.au
Figure 1 – Predicted Stem Water Potential (SWP) versus measured SWP using NIR spectra for Chardonnay vines measured in January and February. Each absorption spectrum was measured on the underside of a leaf on the same shoot as an adjacent bagged leaf used to measure SWP. Irrigation treatments are indicated with different coloured symbols (pd = predawn).