Managing vineyards rootzone salinity and maximising water saving by sub-surface irrigation techniques

Summary

Objectives
To determine how to maximise the potential benefits of sub-surface drip irrigation (SDI) to better manage rootzone salinity and achieve improved water use efficiency. This will be achieved by developing sustainable management systems to maximise salt leaching and minimise nutrient loss from irrigated vineyards. The project will also quantify the potential water and nutrients savings from SDI compared with conventional above-ground drip irrigation.

Background
More than 60 per cent of Australia’s grape growers utilise conventional above-ground drip irrigation systems. Survey data indicate vineyards using record low water volumes and/or those adopting precision irrigation technologies are at great risk from rising rootzone salinity. Sub-surface irrigation offers potential to significantly lower crop water requirements due to reduced evaporation from the soil surface, lower root zone salinity, and lower requirements for other inputs such as herbicides due to reduced weed growth from off-target water application.

In the future, the availability of good quality irrigation water resources will be at further risk from reduced rainfall and increased evaporative demand as a result of climate change. To ensure a sustainable grape and wine industry, it is imperative that more efficient methods of irrigation such as sub-surface irrigation are identified and their impact on water use, root zone salinity and nutrient loss are thoroughly evaluated.

Scope
Experimental sites will be based in two climatically different regions (Riverland and McLaren Vale, SA), having different soil types, applied water quantities and qualities. The sites will generate data for model simulations to quantify water savings, rootzone salinity accumulations and nutrients losses. A Hydrus® computer simulation model framework will be developed to predict the water and solute behaviour under SDI and conventional drip irrigation, simulating a range of climatic and water management scenarios.

Industry benefit
The knowledge generated by this project will form a platform for better vineyard management during periods of variable water availability and quality. Significant quantities of water could be saved by adopting SDI, reducing the reliance of vineyards on declining water resources and offering cost savings through reduced purchase of water. Additional cost savings could be achieved from reduced pumping and associated diesel and electricity use.