Read time: 4 minutes

Daniel Fox, Marrar NSW

Stubble management for weeds and yield

Marrar farmer Daniel Fox is chasing higher yields across his 2100 ha cropping program while also driving down weed seed numbers.

For a few years Daniel has been adding components to his system to conserve moisture and keep herbicide resistant weeds at bay.

“A series of drought years got us started down this track of better soil moisture conservation,” he says. “We have been able to store more water than we expected really and this has been converted into better yields.”

Daniel (left) and David Fox are pleased with the chaff lining chute they have introduced as a harvest weed seed control method on their Marrar farm near Wagga Wagga.

The long-term average rainfall at Marrar, north of Wagga Wagga, NSW is 500 mm and although last year was extraordinarily wet, the 15 years prior to this were relatively dry. This long dry stretch made growers like Daniel and his father David think more about conserving soil moisture over summer and using stubble to protect the soil moisture from evaporation.

As they add more strategies to their management system they are seeing yields rise from an average 2.5 t/ha for wheat to 4 t/ha in years that would have seen the crop suffer due to a lack of spring rainfall.

To tackle increased pressure from annual ryegrass Daniel and David started narrow windrow burning but found that a combination of cutting the crop low at harvest and burning much of the crop residue was impacting on yields. To investigate, they participated in a trial run by Grassroots Agronomy to see if cutting the crop higher, at 30 cm rather than the recommended 15 cm for narrow windrow burning, would still be an effective harvest weed seed control measure.

“The results showed a half-tonne difference between cutting barley low and cutting higher,” he says. “It seems that the taller stubble provides better protection for the soil surface and the trial with the taller stubble had better conserved moisture, which was needed to finish the crop that year, where we had no rain from early September to mid October.”

Highly competitive crops, like this barley, tend to hold annual ryegrass seed heads up high in the canopy where they can be easily collected by the stripper front on the Fox’s harvester.

To maintain the effectiveness of harvest weed seed control Daniel has recently purchased a Shelbourne stripper for the header to collect the grain, and weed seeds, while leaving most of the stubble standing. “Using the stripper we are putting less material through the harvester but still collect grain and weed seed in the crop canopy,” he says. “This means we are picking up yield and reducing the weed seed bank without compromising harvesting efficiency.”

Having used narrow windrow burning for a few years and seeing the benefit of capturing seed from late germinated weeds at harvest, the Foxes have now built a chaff lining chute for the header and are delivering the chaff component, including weed seeds, into a 250 mm chaff line in the middle of the 12 m CTF lap. This maintains most of the crop residue evenly across the paddock and avoids the need for burning. “Having the weed seed concentrated in a narrow band reduces the amount of seed that germinates and also reduces the chance of weed seed being buried and ‘stored’ underground at planting now that we are using a disc seeder,” says Daniel.

Daniel has had no problem sowing through the chaff and is also able to apply more herbicide to the tramlines if the weed numbers appear to be increasing. He is also keeping an eye on the developments of microwave weed control technology as a potential non-herbicide method to treat the tramlines in the future. “We realise that there might be an impact on soil microbes and earthworms but if the microwave is only treating the chaff lines then it could still be a good option,” he says.

Croptopping in non-malting barley, canola and pulses provides an additional opportunity to stop seed set with the chaff lining providing an effective, non-herbicide second knock to support the herbicide.

The cereal stubble persists across the four-year rotation of two cereal crops followed by two break crops, providing more shade and wind protection, and keeping the soil surface cooler.

Daniel Fox has implemented a double break crop system where the cereal stubble is maintained on the soil surface across the 4-year rotation, conserving soil moisture and improving crop yields.

The double break cropping rotation enables Daniel to have a two-year shot at both grass and broadleaf weeds using a combination of herbicide and non-herbicide tactics. “With herbicides we are using robust pre-emergent and in-crop applications and double knocking our knockdown herbicides,” he says. “The non-herbicide tools are collecting weed seed at harvest with the chaff lining chute, strong crop competition from narrow row spacing and haymaking if required. In just three years we have seen a huge reduction in the ryegrass population on the farm.”

During the 2000s David stayed with the canola / wheat rotation they had in place even though it meant that they had a few failed crops, which they converted into silage. “By resisting the temptation to go with a long cereal rotation we avoided the weed blow-out that occurred on some farms,” he says.

The Foxes grow wheat and barley in the cereal phase with an option for oats on their frost-prone paddocks. “Wheat is our mainstay on the higher paddocks where we sow early and the crop flowers in cooler weather, which can make a 2 t/ha difference in yield compared to sowing later,” says Daniel. “We are wanting to raise our average wheat yield from 2.5 t/ha to 3 t/ha, even in lower rainfall and lower radiation years. Likewise, for barley we are confident that significant yield gains are possible in the system we have developed.”

In the broadleaf phase they grow canola and a pulse, usually lupins, and are considering faba bean and lentils as alternative pulse options. They are also investigating whether winter cover crops followed by a summer crop might have a fit in their system to give them the opportunity to use different chemistry at different times of the year to combat weeds.

“No-till and glyphosate generated a big jump in productivity on this farm and now we are seeing another big improvement with new gear such as the chaff lining chute, stripper front and high clearance sprayer,” says Daniel. “We could not have got through last season without the sprayer. It has allowed us to get onto weeds when they are small and cover a big area in the best conditions.”

Doing their own spraying and planting gives Daniel and David the opportunity to monitor their paddocks during the season to keep an eye on weed numbers, which also helps when they go around the farm with their agronomist to plan the weed control program.

A new disc seeder has also made stubble management easier and allowed Daniel to move to 6.5 inch (165 mm) row spacing for all crops. The single disc seeder has 72 units over the 12 m span which, like the sprayer, fits within the controlled traffic system.

Daniel is conscious of brome grass and black oats entering the farm from the roadside so he is spraying through the external fences with a mix of glyphosate and residual herbicide to help minimise the risk of weeds moving into the cropping areas. “We sow right up to the fence to maintain competition and if we need to, we bale the outside lap of the crop,” he says. “After harvest we plough along the fencelines as a firebreak, which is a council requirement.”

The Foxes look for crop traits that provide a competitive edge such as hybrid canola over open-pollinated types and taller wheats such as Spitfire, while still maximising yield and profit from the available moisture. “The 29 year row spacing trial in WA demonstrated that narrow rows produce more crop and less weeds, and we have seen a 400 to 500 kg/ha benefit through less tiller deaths and more heads here too,” says Daniel. “To achieve this it is essential that the soil fertility is able to support the increased production. Our granite soils tend to leach nitrogen in wet years and that has a big impact on yield.”

Related information

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Increase pre-em efficacy through a mix and rotate strategy

Part 1: Control summer weeds for yield and profit
Every $1 spent on summer weed control can potentially return up to $8/ha through moisture and nitrogen conservation. The impact on grain yield as a result of various summer weed control treatments is what Colin McMaster (NSW DPI R&D) refers to as “buying a spring”.  Listen to Colin and Pete Newman (AHRI) as they investigate the $$ benefits of controlling summer weeds.
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Part 2: Increase pre-em efficacy through a mix and rotate strategy
We’ve done a good job of promoting herbicide rotation over the years. And whilst this advice still stands, recent research shows the benefits of mixing herbicides as well.
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Jump to a section

Simon’s client experience with RR Canola and decision-making process 00:27
What’s the decision-making process when it comes to growing a glyphosate tolerant variety over conventional/TT canola? 01:36
Herbicide strategy & resistance testing: 02:44
Timing of glyphosate sprays 05:02
Varietal performance 07:06
Broadleaf weeds 09:33
Dealing with survivors, WeedSmart Big 6 11:12
Desiccation & windrowing 13:48
GM canola marketing 14:46
On-farm storage 15:14

In this new segment, WeedSmart Shorts, our expert agronomists around the country interview experts on topics in a ‘Question and Answer’ video format.
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Simon says there has been uptake by his clients of glyphosate tolerant canola in South Australia, but there has been a varied response.

“We are finding that some are wanting to try a paddock, some are wanting to sit back and see how it goes. So, it is probably very similar to what happened in Victoria when it rolled out there as an option,” he says.
South Australian farmers in the past have been able to control the weeds with the existing canola options they have, says Simon, but what they are finding now is there is an increase in clethodim resistance, particularly at higher rates and so that is what is likely to be driving the decision-making process around what other canola options are available, such as RR canola.
While it is exciting to have another option for SA growers, Simon says it is critical that growers know their ryegrass resistance status before committing to planting glyphosate tolerant canola.
“Testing is the backbone behind the decision making around canola options and so once we’re aware of what herbicides still work effectively, that’s where we’re able to make a good, informed decision.”
Simon said it was important to know what works on ryegrass across the whole spectrum of herbicide groups.
“An example is, I did some testing for a new client recently and one of his populations came back as 80% resistant to glyphosate. Now, had we not done that test and put glyphosate resistant canola into that paddock, we would’ve been facing a disaster, but because we had that information on hand, we knew what our options were and what they weren’t,” Simon says.
 
 

Video
Webinar

Considerations for pre-emergent herbicides with dry sowing

In this webinar, we focus on what factors influence the residual control of weeds by pre-emergent herbicides with a focus on Trifluralin, Sakura and new-to-market herbicides.
Join Chris Davey, YPAG and WeedSmart Extension Agronomist and Mark Congreve, ICAN Senior Agronomist as they assess the sowing issues in South Australia and discuss strategies on using pre-emergents.
Factors covered include

Soil type/texture
Rainfall forecast (after application)
Characteristics of the herbicide
Characteristics of the crop
Sowing time (tine vs disc) – sowing depth, speed, soil throw, stubble
Resistance status

GRDC Spray Application Manual
This Spray Application GrowNotes™ manual provides information on how various spraying systems and components work, along with those factors that the operator should consider to ensure the sprayer is operating to its full potential.
This manual focuses on issues that will assist in maintaining the accuracy of the sprayer output while improving the efficiency and safety of spraying operations. It contains many useful tips for your spray operations.

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Fact Sheet

Farm Business Management Factsheet

Key points

Effective decision-making is at the core of successful farm business management.
Making informed, logical and timely business decisions is crucial to achieving business objectivess.
Understand the different elements that influence how decisions are made and the possible outcomes.
Consider who is responsible for the final decisions in the different areas of your farm business.
Ensure the decision is finalised and implemented in a timely manner.

Want to link to this fact sheet/publication?

Full article can be found here

Fact Sheet

Stewardship First SprayBest Guide

The application of herbicides late in the season to prevent weeds setting seed or to desiccate crops must be carried out with caution and in line with herbicide label recommendations.
It is essential to check if these practices are acceptable to buyers, as in some situations markets have extremely low or even zero tolerance to some pesticide and herbicide residues.

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