• Investigation of weed seedbank decline in nine chaff-lining systems of South Australia demonstrated that growers are achieving high concentration of weed seeds and crop residue at harvest.
• Assessment of the viable weed seed fraction after crop harvest suggests that large residual annual ryegrass, brome grass and Indian hedge mustard seedbanks have been established in cropping field because these species did not decay over the summer-autumn period in chaff-lines.
• Evaluation of chaff-tramlining systems showed that annual ryegrass seedbank decline is independent of chaff-line configuration and chaff density.
• The stability in the weed seedbanks in chaff-lines were consistent with the dry conditions over the summer-autumn period.
• Growers should be cautious of the magnitude of viable weed seeds in chaff-lines before the cropping season and expect variability in the effectiveness of this tactic between seasons.

TRIAL IN PROGRESS. 

For the current information please contact Nimesha Fernando - 0353279189/0434871969

Annual medics are widely
grown on neutral to alkaline
soils that commonly contain
high levels of boron in the
subsoil that reduce plant
growth.
• Boron tolerant barrel, strand
and disc medic cultivars
exist, but all spineless burr
medic cultivars are intolerant
of high boron levels.
• A cohort of boron tolerant
spineless burr medics have
been developed and entered
field evaluation trials at
Minnipa and Roseworthy in
2019.

• Pasture legumes sown
  in 2018 were allowed to
  regenerate in 2019 and were
  grazed with ewe hoggets.
  • Sheep live-weight increased
  on average by 13.8 kg
  (+26%, ~180 g/day) and
  was similar for all legume
  treatments, but differences
  between the sown legumes
  may have been masked by
  volunteer pasture species in
  the plots.
  • Sown legume intake ranged
  from 401 kg/ha (Trigonella
  balansae) to 1461 kg/ha
  (Harbinger medic). Sheep
  showed some grazing
  preference for medic over
  trigonella.
  • The site will be sown with
  wheat in 2020. Crop growth,
  grain yield and quality will
  be measured. Stubbles will
  be grazed. It will return to
  pasture in 2021.

• This is a component of a new five year Rural Research and Development for Profit funded project supported by GRDC, MLA and AWI; and involving Murdoch University, CSIRO, SARDI, Department of Primary Industries and Regional Development; Charles Sturt University and grower groups.
• This trial aims to assess a diverse range of annual pasture legumes in order to determine whether there are more productive and persistent options for the drier areas (<400 mm) of the mixed farming zone of southern Australia.
• Annual medics continue to be the best pasture option for neutral/alkaline soils on the upper Eyre Peninsula. Common vetch is an alternative option where a sown legume ley of one year duration is preferred.
• Building up a seed bank is critical to the longer term performance of the pasture. The aim in the pasture establishment year should be to maximise seed set.
• Levels of hard seed affect regeneration. Legumes with high hard seed levels should be cropped in the year following establishment.

• • The nodulation of strand
  medic was below potential,
  but was not increased by
  inoculation.
  • Trigonella formed more
  nodules than medic, but
  in the end PM-250 strand
  medic was more productive
  and fixed the most N.
  • Legume inoculation (2018)
  increased wheat grain
  protein (2019). The increase
  could not be attributed to
  any measure of legume
  performance.

This is a component of a
five year Rural Research
and Development for Profit
funded project supported
by GRDC, MLA and AWI;
and involving Murdoch
University, CSIRO, SARDI,
Department of Primary
Industries and Regional
Development; Charles
Sturt University and grower
groups.
• This trial aims to assess
a diverse range of annual
pasture legumes in order
to determine whether there
are more productive and
persistent options for the
drier areas (<400 mm) of
the mixed farming zone of
southern Australia.
• The annual medics were the
most productive pasture
legume producing > 2 t/ha
DM and setting > 500 kg/
ha of seed. A new Tetraploid
Barrel medic was the most
productive.
• Astragalus was the most
promising alternative
legume and warrants further
evaluation.

A field trial was undertaken at Kinnabulla (VIC) in 2019 to investigate combinations of sowing time, seed rate and herbicide treatments to control brome grass in barley. Spartacus CL barley was used in this trial to enable the use of Intervix® for post-emergence control of brome grass. In 2019, the trial site received 181 mm rainfall during the growing season (April-October), which was 23% lower than the long-term average for the site. However in December 2018, the site received a heavy downpour of 199 mm, which created good growing conditions for barley crop grown in 2019. In this trial, barley seeding rate did not have a significant effect on either yield (P=0.213), brome panicles/m2 at maturity (P=0.889) or brome seed set/m2 (P=0.409). This lack of effect of crop seed rate on the number of brome panicles and seed set could be related to the high plant available water during the crop and weed life-cycle or due to Spartacus being a less competitive barley cultivar due to its erect architecture. Time of sowing had a significant effect on brome panicles/m2 at maturity and brome seed set/m2. TOS 2 had a lower brome panicle density at maturity than TOS 1 across all herbicide strategies, which was most likely due to low pre-sowing weed kill in TOS 1 as brome grass had not yet germinated. However, brome population that had germinated after the opening rains was killed by glyphosate application prior to seeding barley in TOS 2. As the numbers of panicles were lower in TOS 2, brome seed set was also reduced in TOS2 relative to TOS 1. Herbicide strategy had a significant effect on barley grain yield. As the herbicides reduced the impact of brome on barley, its yield increased from 3.24 t/ha in the knockdown treatment (NIL), to 3.72 t/ha in the pre-emergent herbicides only and to 3.96 t/ha when the pre-emergent herbicides were followed by post-emergent Intervix. Somewhat surprisingly, TOS 2 produced higher yields than TOS 1 across all the treatments, with the greatest difference being 0.46 t/ha in the Nil herbicide treatments. However, the yield difference between the two times of sowing decreased when more effective herbicides were used (0.08t/ha difference between TOS 1 and 2 in pre-emergent only and 0.04t/ha difference when pre-emergent herbicides followed by Intervix). Higher barley grain yield in the later sown crop is most likely due to a significantly greater weed density in barley in TOS 1 than in TOS 2, as large numbers of early germinating brome plants were controlled with glyphosate knockdown in TOS 2. TOS 1 also experienced a mild frost during flowering, resulting in patchy frost damage. Furthermore, May 23 (TOS 2) sowing date still falls within the optimum sowing window for Spartacus, which is an early maturity variety, and TOS 1 on April 29 was earlier than optimum for this variety.

A field trial was undertaken at Washpool in 2019 to investigate combinations of wheat sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was 2249 ± 284 seeds/m2. There was no evidence at this site of any reduction in ryegrass infestation in wheat by delaying sowing by three weeks between TOS 1 (77plants/m2) and TOS (74plants/m2). This result suggests the Washpool ARG population likely has a high level of seed dormancy, reducing the rate of ryegrass germination after the opening rainfall events. Herbicide treatment had a significant influence on ARG plant density (P<0.001). Boxer gold and Sakura + Avadex reduced ARG plant density by 45% and 73% from the untreated control (125 ARG plants/m2). Wheat was much more competitive against ARG when it was sown early. This was made evident by the large increase in ARG seed production when seeding was delayed. When averaged across all other treatments TOS 1 produced 1634 ARG seeds/m2, which was 73% lower than 5974 ARG seeds/m2 produced in TOS 2 (P=0.013). Wheat seed rate had a significant influence on ARG seed production (P=0.005), with the high wheat seed rate supressing ARG seed production by 37% when compared to the lowest wheat seed rate (100 seeds/m2). Wheat grain yield at this site was significantly influenced by the time of sowing (P=0.001), seed rate (P=0.001), herbicide treatments (P=0.001), and the interaction between the time of sowing and herbicides (P=0.011). Wheat was much more tolerant to ryegrass competition when sown early (TOS 1) as shown by the small increase in grain yield in herbicide treated plots. In contrast, there was a significant increase in wheat grain yield in herbicide treatments in TOS 2. The results of this study clearly show that delayed sowing of wheat allows for greater seed set by ryegrass and is also associated with a large yield penalty.

A field trial was undertaken at Minnipa in 2019 to investigate combinations of barley sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was 4168 ± 411 seeds/m². ARG plant density was significantly influenced by the time of sowing (P<0.001), herbicide treatment (P<0.001) and the interaction between the time of sowing and herbicide (P<0.001). There was a large impact of the 3 week delay in seeding barley on ARG plant density. This was particularly evident in the untreated control in which ARG density decreased from 676 plants/m² in TOS 1 to 379 plants/m² in TOS 2. This large reduction in ARG density due to delayed sowing is most likely related to rainfall events in early May, which would have caused weed emergence. Pre-emergence herbicides had higher efficacy in TOS 2 where the density of ARG plants had been reduced by the delay in seeding. This trend held through the season in the untreated control in which ARG spike density decreased from 306 spikes/m² in TOS 1 to 199 spikes/m² in TOS 2. In the trifluralin treatment, ARG produced 5078 seeds/m² in TOS 2 as compared to 9192 seeds/m² in TOS 1, a 45% reduction in ARG seed production. Unlike wheat in 2018, barley grain yield at Minnipa was not significantly influenced by the time of sowing (P=0.644). However, seed rate (P<0.001), herbicide treatment (P<0.001) and had a significant effect on barley grain yield. As stated earlier, there were large benefits of delayed sowing on weed control. In barley a three week delay did not significantly reduce grain yield as it had in the previous year in wheat. Lower yield penalty in barley from delayed sowing may be related to its earlier maturity than wheat.

A field trial was undertaken at Frances in 2019 to investigate combinations of barley sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was quite low (472 ± 143 seeds/m²), which was reflected in low plant density at the site. ARG plant density was significantly influenced by the time of sowing (P=0.037), and herbicide treatment (P=0.009). There was a 37% reduction in ARG plant density between TOS 1 (20 plants/m²) and TOS 2 (13 plants/m²). Herbicide treatment had a significant effect on ARG plant density, with Boxer Gold showing lower efficacy on ARG than Treflan and Boxer Gold + Treflan. Unlike ARG plant density, ARG spike density was not influenced by time of sowing (P=0.171). ARG spike density was significantly influenced by barley seed rate (P=0.016), herbicide treatment (P=0.01) and the interaction between TOS and herbicide treatment (P=0.019). ARG spike density was 34% and 40% lower in medium and high seed rates respectively when compared to the low seed rate. These results suggest an improvement in ARG suppression from increasing barley competiveness with increased seed rate. Barley grain yield at the site averaged 6.6 t/ha. Herbicide treatment had a small (4-6%), but significant effect (P=0.009) on grain yield with Boxer Gold < Treflan ≤ Boxer Gold + Treflan for barley yield.

With the varying results from this project, it is evident that response to N is both site and situation dependant. Further work needs to be undertaken to be able to create a broad rule of thumb around the cost/benefit of feeding N to crops on waterlogging soils

The growing season rainfall in 2019 was below average at Perillup, and the summer cropping demonstration did not suffer from water-logging.

Grain growers in this region believe that the soil drying effects from growing summer crops has the greatest potential benefit to winter cropping yields.

In 2019, there was a 770kg/ha barley yield increase above the control from the plots where cowpea was grown in the summer.

There was a 470kg/ha decline in winter barley yield in the plot that was planted to canola between January 30 and May 9, 2019.

Nutritional requirements of summer crops need to be considered when selecting species. Cowpeas fixed useful nitrogen in the 90 growing days.

The results of this study suggests:

• Whilst the streaming of UAN modestly reduced annual ryegrass N percentage in the tissue, no difference in annual ryegrass biomass or seed production was evident.
• Nitrogen placement did not affect Wheat biomass accumulation (NDVI results), however modest differences in Canopy closure percentage existed. UAN rate and timing however had a greater effect on wheat biomass (NDVI results and wheat biomass cut) and percent canopy closure.
• UAN rate, UAN timing (plus interaction of UAN timing and placement) were found to have significantly affected Radiation interception of the crop in the absence of weeds.
• Nitrogen placement affected the yield and protein content of the grain produced.

The herbicide treatment had a significant effect on annual ryegrass (ARG) plant density (P<0.001) in this field trial at Minnipa. Favourable rain events in May were highly suitable for the activity of both pre-emergent herbicides investigated in this trial. Averaged across the row spacing and seed boot treatments, Trifluralin and Boxer Gold reduced ARG plant density by 20% and 90%, respectively. The density of ARG spikes was significantly influenced by the row spacing (P<0.001), seed boot treatment (P=0.027), and the herbicide treatment (P<0.001). The 25cm row spacing had 20% lower ARG spike density than the 37.5cm row spacing treatment. The splitter seed boot treatment had 12% lower ARG spike density than the narrow seed boot treatment. Trifluralin only reduced ARG spike density by 20% compared to the untreated control, whereas Boxer Gold caused a 73% reduction in ARG spike density. ARG seed production was also significantly affected by the row spacing (P=0.003), seed boot (P=0.01), and the herbicide treatment (P<0.001). The normal (25 cm) row spacing set 38% less seed than the wide row spacing. The splitter seed boot treatment also had 32% lower ARG seed set compared to the narrow seed boot. ARG produced 4792 seeds/m² in the untreated control, which was reduced by 11% by Trifluralin and 69% by Boxer Gold. Presence of ARG at 262 plants/m² in the untreated control, reduced barley grain yield by 8% compared to Trifluralin or 16% compared to Boxer Gold. However, it was still profitable to control ARG with effective herbicide treatments. Based on cash grain price of Feed Barley of $250/t in 2019, Trifluralin would be expected to increase the gross margin by $32/ha as compared $71/ha increase for Boxer Gold.

The results of this study suggest:

• Increasing the canola seeding rate of both OP and Hybrid varieties increased the crops potential competitiveness by increasing early biomass (NDVI) and % radiation interception.
• Increasing canola row spacing increased the crops light interception.
• At Cunderdin, the greatest decrease in ARG establishment in response to canola seeding rate occurred where both OP and Hybrid canola varieties were sown at wider (50cm) row spacing’s.
• The Mingenew site had a significantly higher weed density, reducing the trials competitive effect on ARG density, biomass, and seed production. Sites with lower weed seed banks will be identified in 2019.

At the Mingenew site, canola yield was higher in open pollinated variety (Bonito). At Cunderdin, no effects were identified.

The results of this study suggest:

• Crop emergence was affected by pollination type (greater in open pollinated var. Bonito), increased seeding rates and increased row-spacing, with variety and row-spacing interaction.
• Weed densities were affected by the interaction between variety and row-spacing only.
• Wild radish seed production was reduced by increased seeding rate.
• In general, canola yield was increased by increasing seeding rate and row-spacing in both weedy and weed free situations.

The results of this study suggests:

• Crop emergence was affected by pollination type (greater in open pollinated var. Bonito), increased seeding rates and increased seed size at both the Cunderdin and Mingenew sites, with seed size and seeding rate interactions at Mingenew.
• Weed densities were reduced by seed size and seeding rates at Cunderdin. No significant decreases were identifies at Mingenew due to the high weed densities.
• Ryegrass biomass was reduced by Pollination type (reduced in the open pollinated var. Bonito), increased seed size at both the Cunderdin and Mingenew sites. Seeding rate was found to reduce ryegrass biomass at the Cunderdin site.
• Canola yield was increased by increasing seeding rate and seed size in both weedy and weed free situations at the Cunderdin and Mingenew sites.

• Removing subsoil compaction is critical and for some soil types can dramatically improve access to deep soil moisture.
• Correctly ground-truthing the depth of the compaction layer can drive the success or failure of ripping outcomes.
• Yield increases at the Goomalling site were largely driven by very deep ripping, with either the very deep ripper or delver, with yield increases of 0.55-0.74 t/ha, an increase of 74-93%. The only other treatment to increase yield was mouldboard ploughing on its own with a 0.44 t/ha, 55% yield increase.

Wheat, barley and canola were tested in 2018, and wheat and barley in 2019, representing a range of quality segregations. Trials were located close to Hyden, Kojonup, Jerramungup, South Stirling, Mt Madden, Munglinup, Gibson and Scadden and Salmon Gums.

The 2018 season was characterised by significant autumn rainfall and below average seasonal rainfall for most sites. The first time of sowing was seeded dry for most cereal and canola trials and the second sowing followed opening rains.

There was little evidence from the eight locations in 2018 to support the idea that the latest varieties differ in their response to increasing N and P inputs in wheat, barley and canola such that it could be exploitable by growers. Some interactions between variety and N and P nutrition were identified but responses were isolated and varied with crop and site. For example, significant interactions were measured for wheat yield at Gibson and protein percent at South Stirling; barley yield at Jerramungup, protein at Hyden, protein at South Stirling and screenings at Kojonup; canolayield at Gibson and oil content at Hyden.

In 2019 the Western Australian wheatbelt experienced a late start to the winter growing season and one of its driest. Data from the Bureau of Meteorology show all sites tested in 2019 experienced a Decile 1 season with well below average seasonal rainfall.

The 8 locations for wheat and barley in 2019 tested N rate and timing and supported the findings of 2018 with very little evidence to support the idea that varieties differed in their response to increasing N inputs. In fact, the opposite was true with the four varieties of wheat and barley tested responding in very similar ways for yield and grain quality.

The lack of consistent variety x fertiliser interactions in these environments suggests growers need only consider a crop and not specific varieties in their agronomic management.

N and P nutrition in 2018 and N nutrition in 2019 data supports current farmer practices of adequate basal nutrient upfront for the season, followed by post-emergent nitrogen as season and yield potential warrant.

Conclusions of this study are limited by the site-specific growing conditions and choice of varieties.

• Low potash treatments were easily observed in the lupin rotation (2018). They had less vigour and plant biomass and yielded significantly less than the other treatments.
• The low potash treatments were also low yielding in the 2017 wheat phase.

• Four field trials in 2018 assessed the influence of plant density, nitrogen timing and grazing on yield and quality of three long maturing wheat varieties sown early April in Western Australia.
• Based on yield, Forrest and Longsword wheat varieties are more suitable for the early sowing opportunities in April than growing a mid winter (ie EGA Wedgetail) earlier.
• If there are establishment issues sowing in early April, there is generally no penalty if establishment is down to 50 plants/m². Some varietal specific responses were observed although these responses were also driven by nitrogen timing.
• For early April sown crops, delaying nitrogen application until stem elongation improved yields at Esperance, Katanning and Yuna.
• Grazing did reduce yields by up to 0.9t/ha depending on environment and variety choice, but could be achieved with minimal yield loss for some varieties and environments.

• Water repellence resulted in low plant numbers on the control plots. Ripping with inclusion plates substantially increased crop establishment which were further increased by spading, with the greatest plant density on spaded plots with lucerne pellets added.
• Physical intervention increased wheat yields on a deep water repellent sand. The controls using best practice agronomy on unmodified sands, yielded 0.5 t/ha. Ripping with inclusion plates to 30 cm doubled yield, ripping deeper to 41 cm delivered an additional 0.4 t/ha and spading to 30 cm delivered a further yield increase of 0.5 t/ha, or 1.4 t/ha better than the control.
• The addition of 5 t/ha of lucerne pellets or high rates of fertiliser increased wheat yields when incorporated by ripping to 41 cm or spading, and delivered the highest yields of 3.1 t/ha.

1. Removing subsurface soil compaction can provide benefits over many years.
2. Deep ripping provides the opportunity to address other soil constraints such as sub surface acidity

• Deep ripping provided a 260kg/ha yield increase in barley in 2016,
• Deeper ripping and the use of inclusion plates did not improve barley yield at this site,

• Assessing yield responses on different soil types will guide where future deep ripping work is carried out, with priority given to those soils with the greatest yield increases.

The next step is to engage a Carbon Farming service provider, to work with the proponents to prepare a submission to register both a revegetation project and a natural regeneration project with the Emissions Reduciton Fund.

• Field pea, vetch, faba bean and lentil had 3-125% higher biomass yield and 51-110% higher grain yield than chickpea and canola at Minnipa, 2018.
• Current high demand and grain prices for faba bean meant they were the most profitable break crop species.
• Low grain yield of canola (0.43 t/ha) and chickpea (0.39 t/ha) resulted in these crop species not being profitable as grain crops.
• Field pea and vetch, in particular, have multiple alternative end-use options in dry seasonal conditions that can be utilised to recover crop input costs.