Innovative nutrient management for the Australian Potato Industry

Is the DGT soil phosphorous test any good for potatoes?

Phosphorus (P) is an important plant nutrient that is required to ensure optimum productivity of agricultural and horticultural crops. Australian soils have inherently low P levels, so the application of P fertilisers is widely employed across cropping, horticultural and pastoral systems and is often a significant input cost. Whereas the application of P is vital to ensuring productivity, the over application of P has been shown to pollute waterways, causing eutrophication. It is therefore both economically and environmentally crucial that accurate P application rates are applied to our cropping and pasture systems.

However, there are scientifically documented challenges for the established soil testing methods (Colwell and Olsen P tests) to reliably predict crop P requirements over a range of soil types. Researchers from the University of Adelaide have been working on a new soil P test to overcome this – the DGT test.

The DGT test

Dr Sean Mason and the team at the University of Adelaide have been working on the Diffusive Gradients in Thin-films technology (DGT) as a new method to measure plant available P in the soil and to predict yield responses for a range of crop types. His research has proven the viability of the test for use in a range of Australian soils and broad-acre cropping systems (see factsheet).

However, horticultural crops often require greater amounts of P fertiliser than agricultural crops and commercial potato growing is no exception. Due to the high fertiliser P inputs that are being employed in the potato industry at present, it is possible that over application is occurring, which can affect natural resource condition and threaten economic viability. Hence, applied science based application rates are critical to ensuring the financial and environmental sustainability of the industry.

Project Aim

The aim of the ‘Innovative nutrient management for the Australian potato industry’ project was to assess the applicability of the DGT test for potatoes to determine whether the test can more reliably predict crop responses to applied P fertiliser than the commonly used soil P tests.

The development of DGT critical P values and the uptake of the test and its recommendations by the Potato Industry will reduce the overuse of P fertilisers, ensuring that economically and environmentally sustainable application rates are used, thereby optimising productivity and profitability.

Funded by the Federal Government Department of Agriculture and Water Resources through the Landcare Innovation Grants scheme and delivered in collaboration between Potatoes South Australia, Primary Industries and Regions SA, the University of Adelaide and the South Australian Potato Industry, the research is the first of its kind in Australia for a horticultural crop.

Project Partners

Potatoes South Australia PIRSA RSSA National Landcare Programme The University of Adelaide premiumgreen-logo