Soil preservation key to drought management

Soil and business management a focus of 'Dealing with Dry' forums

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Dr Rob Norton was one of the speakers at recent forums held in Victoria and NSW for drought-affected growers, agronomists and advisers. PHOTO Brad Collis

Dr Rob Norton was one of the speakers at recent forums held in Victoria and NSW for drought-affected growers, agronomists and advisers. PHOTO Brad Collis

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Practical forums provide advice about soil management for drought-affected growers.

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Drought-affected grain growers, agronomists and farm advisers expanded their soil and business management knowledge during practical forums held recently in Victoria and New South Wales.

Forum speaker and Norton Agronomic director, Dr Rob Norton, provided growers with information on soil management, focusing on the nutrition status of eroded paddocks and soil nutrition budgeting and applications.

"In these dry times, even a small amount of soil cover - stubble or even weeds - can reduce the amount of wind erosion," Dr Norton said.

"Having some cover, or creating some surface roughness, will help keep precious topsoil in the paddock.

"Losing just one millimetre of topsoil can result in a one to six per cent yield loss, as key soil nutrients are found in the top two centimetres of soil."

In these dry times, even a small amount of soil cover - stubble or even weeds - can reduce the amount of wind erosion. - Norton Agronomic director, Dr Rob Norton

Dr Norton said he recognised that in some places it might be impossible to retain this level of soil cover.

He said, in these situations, stock should be removed, particularly from sandhills, and a soil management plan should be put in place.

"Watching your paddocks drift can be heartbreaking, but at this time there is little that can be done. It's best to concentrate on the future and look at putting new soil management plans in place," he said.

Erosion prevention measure

In regions with clay soils, growers can look at roughening the soil surface by ridging or ploughing," Dr Norton said.

"This practice can be frowned upon in our modern no-till systems. However, doing this as a one-off to create ridges to reduce erosion can be of assistance.

Losing just one millimetre of topsoil can result in a one to six per cent yield loss, as key soil nutrients are found in the top two centimetres of soil. - Norton Agronomic director, Dr Rob Norton

"A 30-centimetre ridge can provide three metres of soil protection. The success of this is dependent on soil type and the ability to bring up clods, which usually requires clay soil, so knowing your soil type is essential."

Dr Norton said nutrient inputs would vary from paddock to paddock and were dependent on moisture, soil temperature and microbial activity.

"The amount of mineralised nitrogen available to the crop will depend on when the break occurs, soil type and paddock history. We find nitrogen soil levels can be under-estimated following a drought," he said.

"There can be 20 per cent carryover from the year before and increased mineralisation when the drought breaks.

"With these reserves, the need for nitrogen applications in 2020 could be low. In my experience, the rate of nitrogen is more important than timing of application and source."

Some phosphorus carryover was likely in 2020, Dr Norton said, and growers should use soil testing to adjust phosphorus applications.

"Phosphorous is largely preserved in soil year-to-year. However, erosion events can remove the pool as phosphorus is often concentrated in topsoil and is relatively immobile," he said.

Soil testing important for 2020

Dr Norton recommended nitrogen and phosphorus decisions for 2020 crops be based on soil testing.

"Where funds are limited and risks need to be carefully managed, growers could consider reducing nitrogen and phosphorus inputs at sowing and then top-dressing in response to crop growth, but soil testing should really underpin all decisions," Dr Norton said.

Dr Norton urged forum attendees to remember what is really important in tough times.

"Remember your family and community and those who you love. If you or those around you are struggling, seek help," he said.

More information: Rob Norton, 0428 877 119, robnorton001@gmail.com

Useful resources: Lifeline, lifeline.org.au, 13 11 14; Beyond Blue, beyondblue.org.au, 1300 224 636

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