Research prepares growers for drier winters

The effects of lower winter rainfall are being investigated in the Barossa Valley by SARDI and CSIRO scientists as part of a new GWRDC-funded project to develop practical means of maintaining grape quality and vine balance in drier winter conditions.

The three-year ‘winter drought’ project is part of GWRDC’s climate adaptability sub-program, one of the Corporation’s priority areas for investment in 2012-13. The study will be based at the Nuriootpa Agricultural Research Centre.

Principal Scientist of SARDI’s Water Resources, Viticulture and Irrigated Crops science program Dr Michael McCarthy said the outcomes of the project will ‘prepare growers for projected long-term reductions in winter and spring rainfall and help to secure the future of Australia’s wine regions’.

About 20 rainout shelters covered in clear plastic film will be erected in the Barossa-based trial vineyard, remaining in place from late May this year through to budburst. The shelters used in the project are a slight modification of the animal shelters used by the livestock industry, particularly in piggeries.

Annual assessments will involve drip irrigation and micro-sprinklers being used to simulate normal and reduced winter rainfall, with vegetative and reproductive growth being analysed during the growing season.

‘The shelters will exclude all winter rainfall from the vineyard floor, allowing for the simulation of a normal amount of winter and spring rainfall applied with drip irrigation to partially wet the root system, or micro-sprinklers to completely wet the root zone’, Michael said.

The shelters do not, in effect, act as a glasshouse given they are not heated. The clear plastic film will be removed at budburst to allow the vines to experience normal growing season conditions.

CSIRO Plant Industry scientist Dr Everard Edwards will investigate the effects of the drip versus micro-sprinkler irrigation application on root physiology, providing industry with a better understanding of how changing water availability at different points of the season can affect the roots.

Michael said that growers from the Riverland to McLaren Vale have reported that no amount of drip irrigation is a substitute for winter rainfall.

‘If we are going into a warmer, drier environment, we need to know how the effects of less rainfall during winter and spring can be offset by drip irrigation, or whether we need to consider other forms of irrigation, such as the micro-sprinklers’, Michael said.

The second key objective of the project is to look at salinity and how to leach all of the salt out of the soil profile in a warmer, drier climate.

‘We need to know how to manage the salt that is applied to the soil profile during the growing season if winter and spring rainfall is lacking’, Michael said.

In addition to monitoring the effects of irrigation on vine balance and determining the best means of managing salinity during drier winters, the project will also investigate vine storage reserves and vine physiological changes, root zone water content and climate indices.

For more information, contact Elise Heyes, GWRDC Program Manager,

Image: Principal Scientist of SARDI’s Water Resources, Viticulture and Irrigated Crops science program Dr Michael McCarthy (left) with fellow researcher CSIRO scientist Dr Everard Edwards.