Presenter: Tim Pitt (SARDI)
Recorded: 5 May 2016

Irrigation with saline water can increase soil salinity, raise the concentrations of sodium and chloride ions in the leaves and fruit and reduce vine performance. With supplementary irrigation, rainfall supplies the water to leach the salts applied during irrigation. Salt-affected vineyards in supplementary irrigation districts often have high salinity in the soil under-vine and low salinity in the mid-row. This suggests potential benefits from increasing the amount of rain leaching under-vine soils and reducing that leaching mid-row soils. In a study to evaluate rainfall harvesting strategies, the most effective treatments consisted of a plastic covered mid-row mound, which was either exposed or buried beneath the soil surface. Both options reduced average soil salinity by more than 27% and reduced concentrations of sodium and chloride in juice by 28% relative to undisturbed controls. Bare earthen mid-row mounds did not achieve the same salinity reductions, nor did the periodic application of a crusting agent to that mid-row mound. Rainfall redirection showed potential as a salinity management option not requiring the use of additional irrigation water, making it valuable during periods of water scarcity.

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