Read time: 5 minutes

Zero row spacing could take crop competition to a new level

Grain grower Leigh Bryan doesn’t shy away from an unconventional idea. His crop-guided shielded sprayer is working a treat, he is confident with chaff lining and now he is testing the possible advantages of zero row spacing.

His aim is weed-free paddocks with crops growing at their full potential across the 2400 ha of cultivation within 30 km of Swan Hill in Victoria’s Mallee region.

“Being crop-guided, the shielded sprayer provides precise control over weeds and crop volunteers,” he says. “It makes it possible to suppress medic and other hard-to-kill weeds in lentil crops and take self-sown wheat plants out of barley paddocks. Keeping crops as clean as possible.”


Shielded sprayer used to apply paraquat for control of medic in lentils.

Using the shields strategically over the past seven years, Leigh has drastically reduced weed numbers and can concentrate on preventing seed set in just the odd plant here or there. The shields allow Leigh to use more cost-effective pre and post emergence herbicide options to prevent seed set of grass and broadleaf weeds in cereal crops.

“The shielded sprayer also makes it possible for me to crop top at the optimum time to have maximum impact on weed seed set without damaging the crop, regardless of the crop maturity stage,” he says.

The shielded sprayer has played a significant role in managing herbicide resistant brome grass and annual ryegrass.


Leigh’s crop-guided shielded sprayer in action, controlling brome grass in a barley crop.

As a harvest weed seed control tactic, narrow windrow burning was a good ‘get out of gaol’ tactic but Leigh has been chaff lining now for three years. He says depositing the chaff-only fraction in a narrow line between the harvester wheeltracks is a very effective way to keep weed numbers low.

“Dropping the chaff line between the wheeltracks, rather than into the wheeltracks, minimises disturbance of the seeds, reduces weed seed contact with soil and promotes more rotting down over summer,” says Leigh. “The chaff lining chute is also cheaper to make and install than a chaff deck.”

Last year Leigh used the chaff lining chute in all crops except canola and found there was no problem pulling the tines through at planting this year.

“We first tested the idea in clean paddocks hoping to keep them clean,” he says. “We are now completely confident in the system and will be using the chaff lining chute in all crops across the farm this season. It has proven particularly valuable in lentil crops.”

If weeds become a problem in the chaff line Leigh is prepared to band spray the chaff line with pre-emergent herbicide, but this has not been necessary to date.

For the last three years Leigh has also been trialling zero row spacing in a bid to capture optimal yield from his crops. The planter has been fitted with splash plates that spread 35 per cent of the seed at random while the remaining 65 per cent of the seed is sown conventionally, down the tube.


Leigh uses splash plates fitted to his planter to spread 35% of the seed randomly across the soil surface to achieve ‘zero row’ spacing.


Close-up on the splash plate.

“This will only work in relatively clean paddocks,” he says. “With no trifluralin applied the in-crop weed control is reliant on strong crop competition and very, very low weed seed bank. Next year I will be looking at different pre-emergent herbicide options and how they might fit in this system.”

The seeding operation is faster than normal and this helps throw sufficient soil to enable successful germination and establishment for the seeds spread on the surface. In Leigh’s on-farm side-by-side trials, the zero row spacing strips are showing that the idea has promise.

“There are others playing around with the idea of zero row spacing too and I think it has potential,” he says. “In 2016, a strip-trial in barley resulted in the zero row spacing strip yielding 4.994 t/ha compared to 4.889 t/ha in the conventionally sown crop at 375 mm spacing.”

This result gave Leigh the confidence to sow one-third of the farm using zero row spacing this season. To achieve the best results Leigh sows considerably more seed but says this is cheaper than pre-emergent herbicide and results in potentially higher yielding crops. The results of this large scale trial will be very interesting in terms of both weed management and crop yield.


Leigh takes a weed-point view in zero row spacing (left) and 375 mm spacing (right).

“The random placement of stubble is easier to sow through the next year. It still provides trellising for pulse crops and shades the soil to conserve moisture and reduce soil surface temperatures,” he says. “There can be a 10-day delay in germination between seeds sown on the surface compared to those sown into the soil because the surface seed needs rain to germinate.”

When it comes to growing a competitive crop Leigh emphasises the need to get the crop planted on time, keep it healthy and well-fed.

Leigh’s continuous, no-till cropping system includes wheat, barley, canola, lentil, field pea and lupin brown manure. When planning the crop rotation for paddocks he ranks them according to weed burden and uses a 4-year break crop system to clean up paddocks with high levels of grass weeds.

“In a weedy paddock we start with a pea/lupin brown manure, then plant canola, in year 3 we plant a cereal and use the shielded sprayer in-crop then finish with a lentil crop,” he says. “This gives us a 4-year run at grass weed control and then we can return to ‘normal’ rotation with a low weed seed bank.”

Once weed numbers are low, Leigh says it is relatively easy to keep them low through the consistent use of both herbicide and cultural practices. “When weed numbers are low it is possible to look at ways to improve yields and reduce production costs,” he says. “That’s what I hope to achieve with zero row space planting, supported by crop rotation and chaff lining to manage survivors. If there is evidence that weed numbers are increasing, then we have other tools at the ready to stop a weed blow-out.”

Related Articles

View all
Article
News

Never cut the herbicide application rate

Scientific studies have demonstrated that resistance can rapidly evolve in weeds subjected to low doses of herbicide. Some weeds can develop resistance within a few generations. Full rates when mixing herbicides too! When mixing herbicides it is important that each product is still applied at the full label rate to ensure high mortality. Applying different chemicals in one mix can provide an additive advantage. It is important to understand the mode of action of each herbicide on the plant when preparing a herbicide mix. This is just as important for pre-emergent grass weed mixes as it is for post-emergent mixes aimed at broadleaf weed control. ALWAYS READ THE LABEL. Surrounding weed seeds with a combination of pre-emergent herbicides with different modes of action can give a high level of control and help extend the useful life of all the chemicals used. The high level of control must be supported with additional control measures for all survivors. All products with different modes of action must be applied at full label rates for this to be an effective strategy.   Mixing two chemicals with the same mode of action can achieve some additional efficacy, however, the mix should deliver the combined full rate to ensure a lethal dose. The amount of stubble present and crop safety are all important considerations when mixing chemicals. For example, when using a tank mix of Avadex® and trifluralin to control ryegrass in wheat, the rates used will vary depending on the sowing system and level of stubble retention. Be sure to get good advice. Many herbicides on the market are a combination of two or more modes of action within the one product. These products must be applied at the full label rate to be effective. Having dual action does not negate the need to change herbicide products and rotate modes of action. Repeated use of any single strategy will reduce the effectiveness of that strategy over time.  
Article
News

Spray well – correct nozzles, adjuvants and water rates

Spray application is a technical field and growers need to make sure their equipment and application techniques are spot-on. The GRDC Spray Application GrowNote provides detailed information and about 80 videos to demonstrate key skills. Prevent spray-drift The focus of spraying herbicide needs to be on doing the job right so the weeds receive the correct dose and die, and this includes reducing the air borne fraction to a bare minimum. Bill Gordon’s 10 Tips for Reducing Spray Drift Choose all products in the tank mix carefully. Understand the product mode of action and coverage requirements. Select (and check) the coarsest spray quality that will provide effective control. Expect that surface temperature inversions will form as sunset approaches and will likely persist overnight and even beyond sunrise on many occasions. DO NOT SPRAY. Use weather forecasts to inform your spray decisions. Only start spraying when the sun is about 20 degrees above the horizon and when the wind speed has been above 4–5 km/hr for more than 20–30 minutes, and clearly blowing away from any adjacent sensitive crops or areas. Set the boom height to achieve a double overlap of the spray patterns. Avoid higher spraying speeds. Leave buffers unsprayed if necessary and come back. Continue to monitor conditions, particularly wind speed, at the site during the spray operation High water rates don’t have to slow you down Some growers are concerned that increasing the water rate when applying herbicide will slow down their spray operation and cost them money. However, the biggest financial loss during spraying usually comes from a failed spray job. To keep your spray operation as time efficient as possible when using more effective and reliable application volumes, you can: Use nurse tanks around the farm to reduce the time spent travelling back to a central re-fill point. Use a larger pump, e.g. 2.5 inch, to make re-filling quicker. Pre-mix the batch while the sprayer is operating. Many mixes can be held in the mixing tank for up to 6 hours. However, wettable granules and suspension concentrates will need agitation to keep them in solution. For pre-emergent herbicides in high stubble situations, carrier volume has a large effect on the level of control achieved. Across four trial sites Dr Borger’s research demonstrated that ryegrass control with trifluralin or Sakura® increased from 53% control when the carrier volume was 30 L/ha to 78% control when the carrier volume was increased to 150 L water/ha in high Water quality and mixing order Water quality is often overlooked as a possible contributor to herbicide failure and can lead to confusion over the herbicide resistance status of weeds on a property. Water should be considered as one of the chemicals in any mix, given that water quality varies markedly depending on its source. Getting the mixing order right is essential for effective spray results. Don’t start mixing until the water quality is right Podcast – Mixing herbicides Adjuvants Sometimes adding an adjuvant is beneficial and sometimes it is detrimental; and there is an art to knowing how to best deploy these additives. When weeds are susceptible to the applied herbicides, the effectiveness of adjuvants generally goes un-noticed. Correctly applied adjuvants can reduce the impact of low level herbicide resistance by helping to maximise the amount of herbicide taken up by the plant.
Article
News

Clean borders – avoid evolving resistance on the fence line

About one-quarter of glyphosate-resistant populations within broadacre cropping situations across Australia come from fencelines and other non-cropping areas of the farm. Along paddock borders, where there is no crop competition, weeds can flourish and, if not controlled, set lots of seed. The traditional approach has been to treat these weeds with glyphosate to keep borders clean but after 20-odd years this option is now failing and paddock borders are becoming a significant source of glyphosate-resistant weed seed. Weed researcher Eric Koetz said the limited options for managing weeds along irrigation infrastructure and other non-crop areas is a problem and is putting additional pressure on knock-down herbicides in irrigated systems. In some situations, cultivation can be used to kill the weeds and provide a firebreak, but on light soils this may pose an erosion risk and mowing or slashing may be safer options. Another possible tactic is to continue using herbicides but to ensure that a clean-up operation is carried out before any survivors can set seed. Some growers are choosing to increase the heat on weeds along the borders by planting the crop right to the fence and then baling the outside lap and spraying with a knockdown herbicide to kill any weeds and provide a firebreak. Another good option in some situations is to maintain a healthy border of vegetation using non-invasive grasses. In Queensland, buffel grass is a good example of a grass that can outcompete other weeds while not invading crop lands. If only herbicides are used on fencelines, resistance is inevitable. Surviving weeds on fencelines have no competition and access to plenty of soil moisture, so they set a lot of seed and resistance can easily flow into neighbouring paddocks. Other resources It’s time for a glyphosate intervention Farm hygiene cottons on – Cleave Rogan, St George What’s new in management of herbicide resistant weeds on fencelines? Keeping the farm clean – Graham Clapham, Norwin Don’t jeopardise glyphosate for clean fencelines Keeping fencelines clean Resistance risk to knock-down herbicides on irrigated cotton farms

Webinars

View all
Video
Webinar

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. Resources: Ask an Expert column with Colin McMaster GRDC Summer Fallow Weed Management Manual   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. As American weeds researcher, Pat Tranel, puts it, “rotating buys you time, mixing buys you shots (of herbicide)”. Listen to Pat and Pete as they explore the benefits of the mix and rotate strategy.
Video
Webinar

Post emergent herbicides

Resources Spray resistant radish early for best efficacy and yield (Grant Thompson, Crop Updates paper 2014) Herbicide resistant wild radish (Peter Newman) Controlling herbicide resistant Wild Radish in wheat in the Northern Agricultural Region of WA with a two spray strategy (Peter Newman) Diverse weed control: Left jab, right hook (AHRI insight)   Part 2:When is it worth rotating from clethodim (Select®) to butroxydim (Factor®)? Is there any value in rotating the post-emergent herbicides clethodim (Select®) and butroxydim (Factor®)? The research suggests that Factor® will sometimes kill plants that are moderately-resistant to Select® that could help in driving down the weed seed bank. Dr Peter Boutsalis from the University of Adelaide discusses his latest research and observations using both products with AHRI’s Peter Newman.

Videos

View all
Video
Video

Double breaks – a double shot at annual ryegrass

Perhaps you’re a ‘short black’ wheat-canola type, strong on inputs? Or a ‘long black’ type who likes to dilute their rotations a bit more? Or are you a ‘double shot’, throwing in a few break crops in a row for maximum effect? When it comes to managing annual ryegrass populations, Tony Swan and the research team from CSIRO Plant Industry and FarmLink, have shown that ‘double shots’ are the key. Growing two break crops in sequence (broadleaf crop, hay crop or long fallow) was more effective in reducing resistant ryegrass numbers to manageable levels than a single break crop or continuous wheat over a three-year rotation. And it can still be profitable.
Video
Video

RIM: Ryegrass Integrated Management

RIM is a hands on, user-friendly decision support software that allows farmers and advisors to evaluate the long-term cropping profitability of strategic and tactical ryegrass control methods, on the long-term and at the paddock scale. RIM lets you test your ideas: How can you run your ryegrass down and profit up? New rotation? New technique? View the full video here
Video
Video

AHRI features

Sustaining herbicides with harvest weed seed management Rotate, rotate, rotate! Incorporating non-chemical harvest weed seed control methods into cropping systems provides another set of tools to fight weeds and to delay the onset of herbicide resistance. View full video at the AHRI website

Factsheets

View all
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.

Subscribe to the WeedSmart Newsletter