Swinburne scientists have developed new soil-wetting agents that ensure water reaches growing crops to increase crop yield and farming sustainability.

Plants need water to grow. But what happens when your soil won’t let the water in?

In many areas of Australia, our soil has a tendency to become ‘hydrophobic’ – that is, it repels water instead of absorbing it. When it rains, water sits on the top of the soil and runs off rather than soaking in to reach seeds and plant roots.

In areas used to grow crops, water-repellent soil affects crop productivity. Without water, seeds do not germinate and plants grow poorly, reducing the amount of crop produced. Western Australia alone loses around $250 million each year in lost wheat crop production caused by water-repellent soils.

Drying climates represent a global challenge to agricultural production at a time when global population continues to increase.

Millions of hectares at risk

In Western Australia, it is estimated that 3.3 million hectares of agricultural soils are at high risk of water repellence and 6.9 million hectares are at moderate risk. A further 2 million hectares of water-repellent soils are spread across the cropping regions of south-east South Australia and western Victoria. Water repellence has a major effect on Australia’s crop production. Western Australia produces just under 50% of Australia’s annual wheat crop and 10% of the world’s tradeable wheat, which is threatened by these soils.

Swinburne tackled the problem

In 2011, the Grains Research and Development Corporation (GRDC) identified water-repellent soils as one of the most pressing problems for Australian grain growers. The GRDC approached Professor David Mainwaring from Swinburne to tackle the problem. This led to a collaborative project to develop and trial new polymer soilwetting agents.

Mainwaring assembled an international team of complementary experts including polymer and physical chemists from Swinburne, plant and soil nutritionists from CSIRO, microbiologists from the University of Western Australia and X-ray tomographers from the University of New England, who monitored soil water movement. Global chemical company BASF co-funded the research as a commercial partner. Swinburne and BASF co-led the project, which was conducted through the Cooperative Research Centre (CRC) for Polymers.

And the results are promising

The team developed two new polymer agents – one that encourages water movement through the soil and another that improves the capacity of soil to hold water. The agents are applied to the soil when the crop seeds are sown. The agents then remain active in the soils for up to seven months to ensure water is available to the plants throughout the growing season.

In research trials, the new agents increased seed germination by 30%, and increased grain yield by 7%. This represents an increased income of $19 per hectare. With more than 12 million hectares at risk of water repellence in Australia’s southern states, this could increase crop income by up to $228 million per year.

The team also developed a soil diagnostic tool to enable grain producers to choose the most effective combination of agents based on the physical and chemical characteristics of their particular soils. 

So we're telling people about it

To increase awareness of the benefits that polymer surfactants can yield to crop production and farm profitability, Swinburne and its partners participate in annual field days conducted by farming groups and coordinated by the GRDC and BASF.

The two new polymer surfactants and the soil diagnostic test were patented by the CRC for Polymers. With the closure of the CRC in 2017, the GRDC now owns the patents and is managing the licence. BASF will be the sole Australian supplier and distributor of the new soilwetting agents, marketed as Divine Agri and Divine Integrate. All royalties will go towards supporting new doctoral scholarships in polymer science.

This successful research will contribute to agricultural sustainability and economic growth in Australia, and an increase in global food production.

Project lead: Professor David Mainwaring

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