The future of managing acidic soils

News article |

A decade-long soil acidity monitoring program on Eyre Peninsula farms has shown the importance of pH testing as well as testing at varying depths, not just the top 10cm of soil.

These findings come from a 13-year soil acidity program that the Eyre Peninsula Landscape Board has supported with the Department of Primary Industries and Regions, as part of the Board’s Regenerative Agriculture Program.

The five-year Regenerative Agriculture Program, delivered by the Eyre Peninsula Landscape Board and facilitated by Agriculture Innovation and Research Eyre Peninsula (AIR EP), through funding from the Australia Government’s National Landcare Program, is concluding this week, and has seen the final soil acidity workshop delivered to local farmers.

The focus of the Regenerative Agriculture Program has been to learn what sustainable agriculture practices can work on-ground for Eyre Peninsula farmers with farmer-led demonstrations and also involvement in the soil acidity monitoring program to help restore local soil pH levels.

“There has been an explosion of awareness about soil acidity on lower and eastern Eyre Peninsula over the past decade, as farmers have grasped the economic and agronomic penalties of having soil suffering from toxic acidity,” says Sustainable Agriculture Project Officer, Josh Telfer.

“This comes as our farmers now know that acidity can build up over time as well as knowing they can treat it with locally available lime sand.

“This knowledge has been supported by the soil acidity monitoring program which has seen 55 different sites in farmers’ paddocks having soil samples collected over time to provide insights into how different Eyre Peninsula soils respond to treatments as well as what happens when they don’t get treated.

“This has included common farm practices like different crops and fertiliser applications, but also differing the amount and timing of lime applications.

“From this program, we can say that farmers with soil acidity issues should definitely test the soil pH, both in the surface and subsurface with a field kit and also at a lab.

“In addition, we’ve compared sampling at 5cm and 10cm intervals and the data has shown that once liming has begun, farmers really need to be sampling at 5cm increments otherwise you might think your lime is working but it’s just stuck in the top 5cm.

“The soil work has also showed us that when lime is spread, it doesn’t all react instantly with the soil – it depends on the pH, soil texture and other soil properties.

“So it really is important to keep testing soil and trying to work out what is best for your type of soil and how you are working with it.”

The future of managing acidic soils
Testing soil profiles for pH in an Eyre Peninsula paddock, with Tony Wilson from PIRSA.

An Adelaide University researcher, Ruby Hume, has also been involved with the soil acidity program recently, applying cutting-edge spectrometry-based techniques to see small amounts of lime in soil samples. This work was supported by the GRDC.

Mr Telfer says it’s hoped that Ms Hume’s work will be able to shed some light about how much more farmers need to lime following initial applications, in the future. GRDC’s Acid Soils Southern Region project has a range of resources, information and research updates to help with soil acidity management.

“There’s been some really useful data come out of the soil program however there’s always more to learn as soil can vary so much and needs ongoing attention as the basis of our farming practices,” Mr Telfer says.

As part of the Regenerative Agriculture Program, a number of case studies have been written to help local farmers learn from the trials that others have undertaken. These are available on the Board’s Regenerative Agriculture Program page at www.landscape.sa.gov.au/ep/regen-ag.

A recording of the final soil acidity forum is also available to watch - https://youtu.be/N-prxwwIz54.

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