Yarrawonga Chronicle

Best practice to help address sub-soil acidity

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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 subsoil 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.”

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.

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.

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.

 ??  ?? Soil testing can help identify acidity problems in the sub-soil.
Soil testing can help identify acidity problems in the sub-soil.

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