Read time: 3 minutes

Narrow spacing boosts yield in northern trial

Grain growers in medium and high-rainfall areas have much to gain by narrowing the row spacings used in their seeding programs.

That is the advice from weeds researcher Peter Newman, who coordinated a GRDC-funded trial in the northern wheatbelt in 2013 that showed reduced row spacing (using paired row seeding where a single seeding boot creates paired crop rows – usually 75 to 100mm apart) produced higher wheat yields.

He said narrow row spacing could also potentially help crops to outcompete weeds and this was an increasingly important non-herbicide weed control tactic.

Mr Newman, the communications leader with the Australian Herbicide Resistance Initiative and based at Planfarm in Geraldton, says wide row spacings remain common across WA’s wheatbelt.

He says this is due to the practicalities of continuous cropping, seeders needing to handle increased stubble loads, a need to harvest water in a bigger furrows, chemical safety, cheaper seeding bars, less horsepower required for pulling fewer tynes and perceptions that yields are not penalised.

However, new machinery innovations are making it possible to shift to narrower row systems, for example, harvesters that cut stubble shorter and seeders with well-spaced tyne ranks and no wheels in the frame of the seeder bar.

These machines can handle higher amounts of stubble and ensure good herbicide safety.

“All of the research from around Australia is pointing to significant and incremental yield benefits for every one-centimetre reduction in row spacing when wheat yield potential is higher than 1.5 tonnes/hectare,” Mr Newman says.

Yield benefits

Yield benefits were assessed in a GRDC and Department of Agriculture and Food, WA (DAFWA) 2013 northern crop competition trial that was hosted by Mingenew grower Peter Horwood. It compared:

  • single row, paired row and ribbon seeding systems;
  • row spacings of 15cm, 22cm and 30cm; and
  • seeding rates of 60, 90 and 120kg/ha.

The paired row plots were treated with a deep working knife point and Stiletto winged boot that created paired seeding rows 75mm apart – effectively doubling the length of the crop row.

The ribbon sowing involved planting seed evenly across an entire band (ribbon).

As expected, based on national historical research, the narrow row spacing plots (at 15cm) out-yielded the wider row spacings (at 22cm and 30cm) by an average of 240 kg/ha.

This is the equivalent of 16 kg/cm of row spacing and is consistent with findings from a recent GRDC-funded review of 50 years of national row spacing trial data. These findings were published in Row spacing of winter crops in broad scale agriculture in southern Australia.

Mr Newman says the preliminary data appears to show there is no difference in wheat yield between the single row, paired row and ribbon seeding systems at the Mingenew 2013 trial. “We didn’t really achieve a good paired row with the seeding gear we used in the trial, so unfortunately we didn’t see much yield difference between the seeding systems,” he says.

“There also appears to be little wheat yield variation in plots with different seeding rates – as was expected in this weed-free trial.

“But previous research has demonstrated that narrow row spacing in combination with high seeding rates has a big effect on weed seed set and yield through extra competition.”

Weed competition

Paired row seeding using 30.5cm tyne spacing and a winged boot effectively produced the same length of crop row in a paddock as using 15cm single row spacing.

This provided even seed distribution across the paddock and created a similar potential for crop plant density.

Mr Newman says the trials showed narrow row spacing using high seeding rates increased plant density per square metre, suppressing weed numbers and weed seed-set.

He says this supported previous local research that showed increasing seeding rates by 40kg/ha halved seed-set in annual ryegrass populations.

Narrow row spacing economics

Mr Newman recommends growers aim to use the narrowest row spacings that are practical for their area and this should be a consideration when upgrading machinery.

He says a lot of research has been conducted into row spacing and growers could access results when planning their cropping programs.

Mr Newman will be presenting a full analysis of results from the northern crop competition trial at the GRDC-DAFWA Agribusiness Crop Updates in Perth on 24 and 25 February.

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

Subscribe to the WeedSmart Newsletter