Technology targets weeds

Nov. 26, 2023 | 5 Min read
South Australian farmer Tim Williams is looking forward to a farming future with less weed pressure and reduced chemical application.

South Australian farmer Tim Williams is looking forward to a farming future with less weed pressure and reduced chemical application.

Operating a continuous cropping program of wheat barley and faba beans, Mr Williams said initially he was apprehensive about the large outlay for the Seed Terminator prototype (MY17) but after six years using an impact mill, he says the investment is paying off with less weed pressure and less chemical applied.

“There have been massive improvements in mill technology since 2017, resulting in reduced horsepower requirement and increased fuel efficiency.

“Harvest economy kept improving as we progressed from the prototype mill on a John Deere S670 to the 780 and now we have the 2022 model Seed Terminator on a 9.90 New Holland harvester.”

Farming at Conmurra in south-east South Australia in a high rainfall zone (650 mm annually), the Williams use standard screens in the mill to maintain a high weed seed kill rate of 99 per cent across annual ryegrass, wild oats and bedstraw on their 1100 ha property.

They use the barley phase to drive down the weed seed bank.

“We windrow the barley as early as possible, even if that means sacrificing a little yield and cut it as low to the ground as possible. This minimises weed seed shedding particularly in ryegrass, so we can capture the seed and process it through the mills at harvest.”

When the Williams were looking into their options for harvest weed seed control, they chose mills rather than a chaff cart or chaff lining due to the high amount of chaff and limited opportunities to burn, potentially interfering with seeding.

They use a disc seeder on 20cm row spacing and have recently dropped pre-emergents from the herbicide program for barley.

“We hit weeds pretty hard in barley and have reduced weed numbers across the farm.

“With the discs, we rely on Boxer Gold and don’t want to over-use it to the point of generating resistance. Applying pre-emergent chemistry in wheat and faba bean crops is more beneficial in our program.”

When windrowing Mr Williams usually starts on the opposite side of the paddock to where the seeder began, to pick up any lodged weeds in the inter-row and make sure they are cut and placed in the windrow.

“We started out using a windrowing front on the header, which cut the stems quite high.

“The windrowed material then tended to sink into the stubble and was hard to pick up later with the harvester.”

The business now has a self-propelled windrower and cut as close to the ground as possible around beer can height or even lower, in weedy areas.

In the bean phase, the Williams no longer practice desiccation because they find it increases the amount of dust present at harvest.

Instead, they find the straw separation system with the Seed Terminator mill does a good job of keeping the green material out of the mills and off the sieves.

“The standard separation belt in the New Holland is about 60 cm long, but the Seed Terminator belt is over 1.5 m and does a much better job than the baffles we had in our previous John Deere harvesters.

“Keeping green stems and green weeds like thistles and radish out of the mills avoids blockages, even in high yielding and bulky crops.”

Seed Terminator representative Mark Bastian said the company has brought to market several features that make their seed impact mills a very effective option for growers in high rainfall zones.

The Seed Terminator mills can achieve weed kill rates of up to 99 per cent for annual ryegrass.

“There are four screen types available, but the standard screen is the most common in the high rainfall zone. The other options, including blanking screens, bean screens and green screens, can be swapped in just 20 minutes if needed,” Mr Bastian said.

Harvesting in cool, damp conditions in high rainfall zones is not a problem with seed impact mills as there is often less damage to the straw.

The mills are set up to keep the straw and the chaff streams separate resulting in less ‘material other than grain’ on the sieves.

If necessary, the harvest operator can bypass the Seed Terminator mill.

Harvest weed seed control is one of WeedSmart big six tactics to limit the impact of weeds evading herbicide during the cropping phase.

There are three companies offering seed impact mills in Australia and all are WeedSmart partners.

WeedSmart is the industry voice delivering science-backed weed control solutions to enhance on-farm practices and promote the long term, sustainable use of herbicides in Australian agriculture. WeedSmart has support from the Grains Research and Development Corporation (GRDC), major herbicide, machinery and seed companies, and university and government research partners, all of whom have a stake in sustainable farming systems. The GRDC is a Platinum investor in WeedSmart to ensure Australian grain growers have access to world class research in strategies to mitigate weeds and control herbicide resistance.

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