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The intricacies of a tall stubble system

Unpacking the pros and cons of retaining tall standing stubble has led Dylan Hirsch to host trials on the topic for a GRDC-invested project.
Photo: Evan Collis

Moisture retention is the number-one priority for Dylan Hirsch, who crops at Latham in the medium-low rainfall region of Western Australia, 250 kilometres north-east of Perth.

For this purpose, Dylan has been exploring the role that retaining tall stubble might have in his cropping system.

“It is proving to be a complex change, raising many questions and posing implications for machinery use,” he says.

Dylan crops 5800 hectares of primarily yellow sand plain country with his parents, Bradley and Joanne. Growing season rainfall is approximately 180 millimetres, but has been declining with drier winters and more summer rainfall.

“Our challenge is to make the most of the moisture available to us, to capture and retain rainfall, sow in a flexible and timely way and ensure crops are avoiding heat stress towards the end of the season. Additionally, we need to look after our fragile sands that are prone to erosion and evaporation,” he says.

To create tall standing stubble, Dylan is using a stripper front on his harvester.

This front works well in high-yielding cereal crops and can create stubble as tall as 60 centimetres. When done right it will leave the backbone of the cereal head (rachis) behind.

“However, harvest performance, capacity and losses are conditional to variety, crop biomass and the weather, so we will only use the stripper when conditions are right.”

Sowing into paddocks with tall stubble poses further challenges and Dylan is using a double-disc system.

“I learnt a lot about different sowing systems when travelling overseas on a Nuffield Scholarship in 2018. This prompted me to look further into the technology and I travelled east in 2019 to learn more about disc seeders.”

Following seeder technology development on social media and talking directly to growers also guided Dylan in constructing his own double-disc seeder, at significantly lower cost than buying a unit.

“This seeder gives us greater flexibility and capacity, as we can even sow during and immediately after rainfall events and we can sow on to stubble rows with minimum disturbance, reducing weed germination. We also retain the previous year’s residue as soil cover, which will insulate our crop from our hot April weather.

“As we have only a single shoot with our disc seeder, in certain conditions we need to broadcast fertilisers in a separate pass to avoid any fertiliser toxicity by placing fertiliser in the narrow row with the seed.

While retaining stubble and ground cover retains more moisture, there are many potential issues. The range of herbicides we can use is restricted as they can tie up on the high stubble loads. The increased stubble load and changes to canopy temperature may have implications for frost and diseases.

To learn more about the risks and rewards of tall stubble, the Hirsches are hosting a field site as part of a Liebe Group-managed, GRDC National Grower Network investment examining tall stubble systems.

As well as measuring aspects of these paddock-scale trials, the project will also be considering the economics, dissecting the operational efficiencies that arise with the use of the new machinery and other costs of the tall stubble system.

Read also: The WA tall stubble story – a tale of pros and cons.

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