What was it all about?

This project ran from 2016 to 2020 to assess groundwater quality in areas of potato production in South Australia (where groundwater quality is most variable) and investigated how regional and seasonal water-quality variability impacts on potato production and quality.

The project delivered four Salinity and Potato Production fact sheets (available in the ACT NOW section below) that outline effective management strategies and tools for sustainable and profitable potato production under varying soil and water conditions.

On average, Australia grows 1.3million tonnes of potatoes per year, accounting for 40% of all vegetable production. South Australia is the country’s largest producer, growing 385,000 tonnes annually, however growers in key production areas are challenged with saline irrigation water sources and variable soil salinity which limits crop potential.

Irrigation water quality was variable between regions, with major groundwater systems driving regional water quality, however all was consistently saline with conductivity levels (ECw) ranging between 1.7 and 3.9dS/m. Sodium and chloride were dominant salts, with levels 2-8 times above the desirable threshold for potatoes.

The application of these highly saline irrigation water supplies not only impacted directly on potato health, but also added salts to soils, where root zone salinity levels increased throughout crop life and soil structure declined. Inherent soil variability within centre pivot irrigation systems and the presence of hydrophobic sands, combined with long periods of heat stress, created additional challenges for growers to achieve optimal potato production.

The team assessed management options available for growers to maximise productivity and profitability. Understanding irrigation water quality, what salts cause high conductivity levels, and what salts are applied in fertiliser programs formed the foundation of all trial work.

Fertilisers low in chloride and high in soluble calcium, nitrates, sulphates and phosphorus, were trialled to help improve chloride and sodium flushing, as well as improve uptake of nutrients that are otherwise unavailable in highly saline conditions. Biological products designed to boost nutrient and moisture uptake and improve disease resistance, such as mycorrhizal fungi, were also trialled, along with a soil conditioner for improved water infiltration and wetting uniformity within the rootzone.

All the trials yielded promising results, presenting cost effective opportunities for fresh and processing potato growers to improve production across the major growing regions of South Australia. The outcomes of this project have been shared with industry and growers, supporting long-term productivity goals and competitiveness in overseas markets.

ACT NOW

Access the four Salinity and Potato Production fact sheets prepared by the project team to share the research outcomes:

• Monitoring for improved management
• Know your salts to better manage potato nutrition
• Managing hydrophobic soils in potato production
• Organic soil amendments, biologicals and biostimulants

Read about Tim Heysen’s involvement with the project on page 8 of 2017 Grower Success Stories – Real results from the Potato R & D levy

Read about the project in this article, Understanding the Impact of Groundwater on Potato Crops, on page 8 of the July 2018 edition of Potatoes Australia.