Water Watch: Grape Days Central Otago

That was one of the messages shared at the Central Otago Grape Days event in July, alongside talks about measuring carbon emissions, using artificial intelligence, improving efficiencies, practicing precision irrigation, and ensuring location-specific frost fighting.

New Zealand Winegrowers (NZW) General Manager Sustainability Edwin Massey told attendees that the looming regulations for Freshwater Farm Management Plans (FMP) would affect all vineyard properties of 5 hectares or larger. Sustainable Winegrowing New Zealand (SWNZ) aims to be able to assist growers with developing plans and potentially auditing them, but at this stage will not be involved with FMP certification, he said. However, NZW is engaged with the Crown to amend current legislation so that SWNZ has the potential to play a more comprehensive role in assisting members to develop plans and certify and audit them. “We are New Zealand’s most sustainable sector for land use,” Edwin said at the event. “We are a lower-risk industry to freshwater takes, so hopefully this will impact what we need to do and the costs.” The new regulations went live in Southland in August and were likely to begin in 2024 in Central Otago, at which point growers would have 18 months to develop and lodge their plans.

The Grape Days audience also heard from Plant & Food Research Principal Scientist Brett Clothier, who discussed his latest work with the Vineyard Ecosystems programme. Brett explained findings from the use of drainage flux meters or “giant rain gauges buried in the soil”, which mimicked how water behaved as it entered the soil, including capillary action, leaching, and drainage. His work offered insights into how much water “quits” the soil as grey water or drainage water. Viticulture returned more water to the environment than it took for plant use, Brent said. He reiterated that investing in soil capital resulted in enhanced support services from the soil, ensuring more efficient irrigation use.

John Bright, from Aqualink in Canterbury, discussed the use of the online tool MyCatchment (mycatchment.info) to help with the process of irrigation planning, consenting and design. “Put the very best, most favourable irrigation system in that you can afford”, he said. “Use an independent certified irrigation designer, and then take it to a range of installers for quotes.” Good planning and design from day one created the potential for long-term effective and efficient irrigation, John told attendees, emphasising the need to be future-focussed. Irrigation demand would increase over time, while water availability and security would very likely reduce, he said, also noting that storage would become increasingly important as extreme weather events brought droughts, while availability of alpine-fed water sources decreased.

Central Otago Grape Days drew a range of talent, including Marilyn Duxson, Tom Bullen, Mike Winter, Nick Gill and the local Young Viticulturist of the Year winner Nina Downer. Take home points from a great day included being prepared for changes to management, such as irrigation use, storage, and design, putting freshwater at the forefront of production plans, and considering location when making frost-fighting decisions, including an understanding of inversion and the behaviour of downward flows of cold, dense (katabatic) air.

Rachel Petrie is senior lecturer and vineyard manager at Otago Polytechnic’s Central Otago Campus.