With wet conditions saturating large areas of crop production land across Victoria and Tasmania, a GRDC project is identifying ways to maximise crop performance when waterlogging occurs.

Waterlogging creates a stressful environment that can reduce yields and, in the worst cases, leads to plant deaths.

According to project leader Greta Duff, Senior Research and Extension Officer, Southern Farming Systems (SFS), waterlogging is the main issue raised by growers in the high rainfall zone of Victoria and Tasmania.

“Growers want solutions to waterlogging and a starting point from which to salvage their crops after it occurs,” says Ms Duff.

Under waterlogged conditions, nitrogen is lost from the soil through denitrification and leaching. Plants also have a limited ability to take up nutrients when soils are waterlogged.

With SFS, the GRDC project set out to help farmers implement nutrient strategies to recover a waterlogged crop.

In 2021, SFS established three trial sites in Victoria – Hamilton, Streatham and Vite Vite – and one in Hagley, Tasmania. All sites experience waterlogging.

Different treatments of urea, sulphate of ammonia, Urea Ammonia Nitrate (UAN) and trace elements were applied across the trial sites.

Ms Duff says that the aim of the trials was to provide growers with knowledge and resources to help salvage their paddock after waterlogging occurred.

“Providing crops with adequate nutrition is of upmost importance to help the plants recover from the stress of waterlogging,” she says.

“Applying any form of nitrogen, whether its granular or liquid, seems to be the best bet to give crops a chance at recovering.”

She added that improving paddock drainage is the underlying solution.

“Now is the time to look at paddocks and see where waterlogging is occurring – where the water is pooling, how it is moving, how severe it is and how the crops are affected.

“Assessing the paddock now will enable growers to see where they need to start with drainage work.

“Growers who have invested in drainage say that while it is expensive, it is one of the best investments they have ever made.”

GRDC has made significant investments to help growers reduce the impact of waterlogging.

“Waterlogging is one of the biggest concerns raised by growers in the high rainfall zones of Victoria and Tasmania and this constraint has been both dramatic and very costly in recent seasons,” says Andrew Smith, GRDC Manager Agronomy, Soils and Farming Systems, for the southern region.

“Over the past few years, GRDC has invested more than $2 million in a suite of projects to help find solutions including those related to sub-surface water management and into the future of plants which are better adapted to waterlogged conditions.”

View the results of the 2021 SFS waterlogging trial results and keep up to date with project outcomes on the GRDC project landing page: Strategies for waterlogged crops in the High Rainfall Zone of the Southern Region.