Agricultural
12 August, 2024
Experts discuss annual ryegrass management at GRDC update
Over 120 growers and advisors attended the Grains Research and Development Corporation’s (GRDC) update on 1st August at the Pittsworth Motor Inn to hear a number of experts give insight into the latest research, development and outcomes of profitable farming practices.
“2023 was a significant year for GRDC,” Graeme Sandral, Grower Relations Manager (North) said.
“After extensive consultation with growers and the grain industry we announced our RD&E [research, development and extension] 2023-28 plan and a commitment to invest more than a billion dollars in research, development and extension to deliver improved outcomes for Australian grain growers.
“For more than a quarter of a century GRDC has
been driving grains research capability and capacity with the understanding that high quality, effective RD&E is vital to the continued viability of our grains industry,” Mr Sandral said.
A range of topics was touched on including strategies for improving dispersive soils, examining the greenhouse gas (GHG) emissions of farming practices, exploring soil organic carbon in long-term cultivated soils, weed management, impacts and management of fall armyworm, and the planting and harvesting of mungbeans.
The update included a number of guest speakers across three sessions beginning at 9am.
SOILS & GREENHOUSE GAS EMISSIONS (GHGs)
The first session focused on the soil constraints that limit agricultural productivity.
Cameron Silburn of the Queensland Department of Agriculture and Fisheries (QDAF) spoke of a number of trial sites, one of which is located at Millmerran, that have experimented with a number of amelioration strategies including shallow ripping, deep ripping, banded nutrients, deep elemental sulfur, surface and deep gypsum, and deep composted manure, to improve soil dispersion.
Mr Silburn said soil testing should be the first step for all growers beginning their soil amelioration journey, to determine the soil constraints and consequently amendment options available to them.
Lindsay Bell spoke of Commonwealth Scientific and Industrial Research Organisation’s (CSIRO) research into the GHG footprint of different farming systems.
A number of experiments have been underway at seven locations across Queensland and New South Wales, the closest to our area being at Pampas.
Mr Bell said the research serves as a benchmark for grain production in eastern Australia, and offers detailed insight into how altering agronomic practices such as crop rotation, nutrient inputs, and cultural methods, can impact GHG emissions and intensities.
A PhD student at the University of Queensland (UQ), Meghan Barnard, presented the impact of long-term cropping on the composition of soil organic carbon on the Downs.
“The conversion of native land to agricultural land drives the loss of soil organic carbon, and contributes directly to GHG emissions,” Ms Barnard said.
This study showed that the impacts of cropping on soil organic carbon can be better managed by prioritising the physical protection of soil organic matter rather than efforts to change the chemistry of the soil organic carbon.
HERBICIDES & WEED CONTROL
The second session included speakers from Jubilee Consulting, QDAF, Nutrien Ag Solutions and WeedSmart, with a focus on herbicides and weed management of milk thistle, fleabane, and ryegrass.
Andrew Somervaille (Jubilee Consulting) spoke about the benefits of Group 14 herbicides as an additional mode of action for pre-emergence weed control, and knockdown control of a range of broadleaf weeds.
In addition, Jeff Werth (QDAF) presented convincing evidence that crop competition through the narrowing of row spacing and/or increased crop density can reduce growth and seed production of feathertop Rhodes grass (FTR) and sow thistle.
There was much discussion in the second session around the appearance of annual ryegrass (Lolium rigidum) on the Downs.
Nutrien Ag Solution’s Garry Onus from Moree highlighted a number of management tools to prevent seed set, including spray topping, crop topping, row direction, crop rotation, and crop competition.
He said to not under-estimate the weed, but growers should test their population for resistance.
Before lunch, Paul McIntosh of WeedSmart, hosted a consultant panel with the three experts on problem weeds.
There was a question as to whether or not atrazine would do a good enough job removing annual ryegrass.
“I expect it would do the job, it’s only a shallow germinator, I haven’t used it yet,” Mr Onus said.
However, Mr Somervaille said his experience with atrazine is far less effective as a pre-emergence herbicide.
“My experience with atrazine, pre-emergence, on the Downs at least, is it’s persistence is far less than what it used to be,” he said.
“I think that’s partly because of the accelerated microbial breakdown, you’ve got a host of microbes that have adapted to the use of 40 to 50 years atrazine use, and we’re reaping that now.
“So, for example, three years ago over at Mt. Tyson on the river at Linthorpe Creek, I applied 2kg of atrazine and within 6 to 8 weeks there were weeds coming through.
“So, I’m thinking that it’s probably not a great strategy, but what would be, for those who have the opportunity to rotate out of winter crop, is to actually utilise a winter fallow in those areas,” he said.
Mr McIntosh and Michael Thompson (GRDC) travelled to Bongeen in November last year and found ryegrass on the roadside, around guide posts, in table drains and along some irrigation channels.
“It takes some controlling,” Mr McIntosh said.
“Two to three years ago out at Norwin, I was coming out of the paddock there one very hot day, and I saw these green shiny plants in the table drain.
“When I did some history, of that particular part, two bales of hay fell off into that table drain near the Norwin silos some years ago, and the truck went on to the feedlot.
“They came back and picked the two bales of hay up, and right there where that hay fell out, was a heap of ryegrass coming up,” Mr McIntosh said.
“When I went back to visit after a bit of a wet season that ryegrass was going down the table drain toward Norwin silos and round the corner heading toward Cecil Plains.
“It has the ability to move with water in overland flow, going everywhere, so be on the watch out for it,” he said.
Mr McIntosh put the question on table, as to what suggestions can be made for annual ryegrass growing from Dulacca, Miles, and all the way down the Darling Downs.
“Be vigilant, bar the water dispersion and overland flow,” Mr Onus said.
“The spread is pretty slow, but if the header picks it up, that’s going to stir it around a bit.
“You’ve just got to be vigilant, it can creep up on you,” he said.
FALL ARMYWORM & MUNGBEAN HARVEST
The final session of the day welcomed Joe Eyre (UQ), Melina Miles (QDAF) and Ross Pomroy (Nutrien Ag Solutions) on the impacts and thresholds of fall armyworm in sorghum and maize.
They also shared management guidance for the 2024/25 season.
Discussion on mungbeans followed, with Jayne Gentry (QDAF) presenting a report on the mechanical, and chemical desiccation of mungbeans.
UQ’s Kylie Wenham covered mitigating mungbean risk, and the optimum sowing times, and ideal conditions for high yields.
Ms Wenham said the basic principles of growing mungbean have not
typically changed, but understanding of how they yield and the key drivers within different environments has improved.
Sharing the results from their research is a key role of the annual GRDC updates, which bring together some of Australia’s leading grain research scientists and expert consultants.
Producers were able to ask questions of the panel of experts on mungbeans before the update came to a close around 3pm.
