Best practice liming project to help address sub-soil acidity

23 August, 2021

Word Count: 499

Best practice liming project to help address sub-soil acidity

Acid soils have long been known to be a major constraint to crop and pasture production in north-east Victoria, with the reacidification of previously limed soils and pH stratification becoming increasingly important issues for the region’s grain farmers.

Given the local significance of the issue, Riverine Plains is pleased to be leading a new GRDC investment, Best practice liming to address sub-soil acidity in NE Victoria, which aims to increase awareness of acidity and pH stratification in local soils, as well as the management tools available to farmers.

Riverine Plains Project Officer, Jane McInnes, explained that acid soils can severely limit production rates and economic returns, especially when growing sensitive crops such as pulses.

“While many grain growers are working towards maintaining surface soil pH values above pH 5 through regular soil testing and targeted lime applications, we are increasingly seeing highly acidic layers in the 5-20cm sub-soil affect production” said Ms McInnes.

“Surface-applied lime only moves very slowly down the soil profile and this can mean that lime may only be acting in the surface zone, failing to reach acidic layers further down the profile” she added.

As part of the project, Riverine Plains will establish a replicated trial to look at how the incorporation of lime can improve the distribution of lime down the soil profile and lessen the impacts of soil acidity on subsequent crops. Some of the techniques which are being considered for the trial include spading, discing, ripping and prickle-chaining.

The lime treatment trial will be established during February 2022 and will compare crop performance of subsequent crops across the different treatments. These results will then be used to inform an economic analysis of the treatment options, while intensive soil sampling will also help to understand differences in nutrient availability, pH and soil organic carbon between treatments.

“Lime quality can be quite variable so we will also be establishing a demonstration trial at the same site looking at the quality effect of lime” explained Ms McInnes.

The demonstration will also include an elemental sulfur treatment to accelerate acidification and give an indication of the future effects if lime was not applied.

Project steering committee member, Rutherglen farmer and GRDC southern panellist, Andrew Russell, said that because soil testing has traditionally been done by bulking surface and subsoil layers together, many farmers may be unaware they have an acid soil layer that is limiting production.

“By raising awareness of this issue, and ways to manage it, we hope to be able to improve the effectiveness of local liming programs in the long-term” he said.

For further information about the project, or to learn how to become involved, please contact Riverine Plains Project Officer, Jane McInnes on 03 5744 1713 or email jane@riverineplains.org.au.

Riverine Plains is an independent farming systems group specialising in farmer driven research and extension across north-east Victoria and southern New South Wales. For more information, or to become a member, please visit www.riverineplains.org.au

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More Information or Interview:

Jane McInnes, Project Officer, Riverine Plains on 03 5744 1713.