Oaten hay yield and quality response to agronomic levers

Take home messages

• Oaten hay varieties respond similarly to different agronomic levers – choose high yielding varieties with best genetic quality traits to optimise production of export quality hay.
• Sowing early maximises hay yield but not always quality – let the variety maturity rating guide the ideal sowing time. Sow with higher plant densities than grain crops, and supply 60–90kg/ha of nitrogen depending on starting soil N levels to drive biomass without penalising quality.
• Cut oaten hay crops at watery ripe (Z71) not later to avoid the risk of hay quality declining.
• Strobilurin fungicides applied to manage crop disease four weeks before cutting reduced discolouration by saprophytes on the outside of the windrow compared to the control.

Background

The Australian export fodder industry has increased year on year over the last decade, now exporting about 1.2 million tonnes of hay, valued at more than $500 million. Over the past 10 years, the main export production states were Western Australia, South Australia and Victoria, averaging 40%, 31% and 21% of production volume respectively (AgriFutures Export Fodder Program Strategic RD&E Plan 2021–2026).

The AgriFutures Australia Export Fodder program invests in oaten hay quality research to influence grower practices and strengthen Australia's position as a supplier of choice within our export markets.

The National Hay Agronomy (NHA) project (2019–2022) was an investment with the objectives to:

• improve agronomic guidelines to maximise oaten hay production and quality (variety selection, nutrition, optimum seeding date to increase quality and decrease risk)
• clarify the potential for growth regulators in oaten hay production
• update disease management guidelines for oaten hay crops.

Method

To improve agronomic guidelines, a core trial series evaluated the performance of eight different varieties sown with three or six different nitrogen (N) rates and two sowing dates across three seasons (12 trials located in Western Australia (WA); Muresk (2019 to 2021), South Australia (SA); Hart (2019 to 2021), Victoria (Vic); Kalkee (2019), Rupanyup (2020), Wallup (2021) and New South Wales (NSW); Yanco (2019), Yenda (2020), Wagga Wagga (2021). Additional regionally specific trials were sown to 1) Evaluate five new oat varieties in WA; Muresk (2021) and SA; Jabuk, Tarlee (2021)), 2) Compare Kingbale versus its parent Wintaroo (four trials: WA; Wongan Hills, Muresk (2020), SA Tarlee, Lameroo (2020)) 3) Measure the effects of growth stage at cutting on hay performance (two trials: WA; Muresk (2020), Vic; Rupanyup (2020)), 4) Investigate the role of grazing in mixed farming systems and its impact on oaten hay (four trials: NSW; Dirnaseer, Gerogery (2020), Yenda (2020, 2021), Wagga Wagga (2021)), and 5) Identifying the target plant density for export oaten hay in NSW; Gerogery (2019 to 2021), Yanco, Marrar (2019), Dirnaseer, Yenda (2020), Wagga Wagga (2021)).

Glasshouse screening and field trials evaluated Moddus® Evo for lodging management (four trials: WA; Nunile, Highbury (2019), SA; Tarlee (2020), Vic; Kalkee (2019)) and ProGibb® SG for assisting panicle emergence (four trials: WA; Wongan Hills (2020), SA; Booleroo, Lameroo, Tarlee (2020)). Note, ProGibb® SG is not registered for use in oaten hay.

The project conducted a review of plant diseases impacting oaten hay and produced disease management factsheets with updated management guidelines for red leather leaf, Septoria, oat stem and leaf (crown) rust. Disease surveillance occurred on 20 crops annually (Vic, WA), and disease management trials were conducted for red leather leaf (RLL) (six trials: Vic), Septoria (five trials: WA), oat leaf (crown) rust (two trials: WA) and saprophyte suppression (management of weather damage) (five trials: WA, Vic).

Results and discussion

The following summarises key oaten hay agronomy results from the National Hay Agronomy trials 2019 to 2021.

Time of sowing

• Earlier sowing (late April/early May) increased the opportunity to maximise hay yield but did not always maximise hay quality compared to a conventional sowing time.
• Earlier sown hay tended to have thicker stems and lower crude protein, but had higher water-soluble carbohydrates (WSC) (except Koorabup) compared to sowing in late May/early June. This trend was not always consistent across sites and years but was the general trend when the data was averaged.
• The variety response to sowing date was variable, and not easily predicted at the start of the season; often the pattern of in-season rainfall had the most influence.

Nitrogen rate

N applications drove more biomass, taller and greener plants, and increased the risk of lodging, especially in susceptible varieties.

• Peak hay yield was achieved with 90kg N/ha, although 60kg N/ha was adequate when sites received below-average rain during critical growth periods.
• Nitrogen was not a major driver of hay quality defects (thick stem diameter, or high acid detergent fibre (ADF), neutral detergent fibre (NDF) or lignin), but was linked to increased crude protein and decreased WSC. Applying >90kg N/ha increased the risk of not meeting industry WSC guidelines for premium hay of more than 22%.
• Varieties responded the same to increasing N rates for hay quality traits, across a range of seasons. More N could be applied to varieties with higher genetic WSC, for example, Yallara, before they drop a grade, potentially growing more hay of export quality.
• The response to N was generally consistent between the planting dates, albeit with varying degrees of impact.
• Across trials, both season and variety were the larger drivers of hay quality rather than the rate of N applied.

Variety choice

Hay yield and quality was assessed for four dual-purpose varieties (Carrolup, Durack, Williams and Yallara) and four hay-only varieties (Brusher, Koorabup, Mulgara and Wintaroo).

• Brusher and Wintaroo were the leading varieties for hay yield, when yields were averaged across years, sites, N treatments and sowing dates, at the first sowing date (late April/early May), while Wintaroo had the highest yield of the second sowing date (late May/early June). The varietal hay yield differences at the early sowing date were 1.0t/ha and 0.6t/ha when sowing was delayed. Brusher lost the most hay yield with delayed sowing (1.8t/ha), while Carrolup and Durack were the least affected, with only a 1.0t/ha reduction in yield.
• Brusher and Wintaroo were most likely to experience lodging, followed by Mulgara. Varieties differed in stem diameter, with Carrolup, Durack and Koorabup averaging 0.5mm narrower stems than Mulgara, Williams and Wintaroo. Wintaroo was most likely to produce hay with a stem diameter wider than 6mm, the upper limit for premium hay.
• Brusher was more variable across years, sites, N treatments and sowing dates in its hay greenness, as measured by a Soil Plant Analysis Development (SPAD) chlorophyll meter, than the other seven varieties. Durack hay was the greenest, averaging five SPAD units darker than Carrolup, Mulgara and Wintaroo, which were the lightest green. Williams varied the least in the greenness of all the varieties. Their greenness was related to their performance and suitability for the different sowing dates.
• Hay variety quality traits were measured in the NHA trials.
  • Digestibility – Brusher, Mulgara and Yallara were more digestible than Durack.
  • Crude Protein (CP) – Williams had the highest CP and Wintaroo the lowest.
  • WSC – Yallara had the highest WSC, and Koorabup and Williams had the lowest.
  • ADF – Koorabup and Wintaroo had the highest average ADF, and Brusher and Yallara the lowest.
  • NDF – Koorabup and Wintaroo had the highest average NDF, and Yallara had the
    • lowest.
  • NDF digestibility after 30 hours (NDFDom30) – Brusher, Mulgara and Yallara hay had higher levels of rumen digestibility after 30 hours than Carrolup and Durack hay.
• Yallara, a quick dual-purpose variety, was best performing for quality, with the highest WSC and lowest fibre levels, and thin stems. Yallara had comparable hay yield to Brusher and Wintaroo, with lower lodging risk and similar hay colour. Its flag leaf is erect, making it more vulnerable to impact by adverse weather in a dry finish. Yallara can be a bit quick for better seasons in higher rainfall areas.
• New specialist hay variety Koorabup (released for superior Septoria resistance) did not perform well when benchmarked against Brusher, yielding 0.5t/ha lower, with a higher ADF and NDF risk, lower WSC, but had similar hay greenness and stem diameter.

New hay varieties

Intergrain are working hard to breed new oat varieties with improved hay and grain profitability (Allan Rattey, pers. comms. January 2023).

• Wallaby is a mid-late maturity line with market leading quality, suitable for sowing in the last week of April until the third week of May, like Kingbale and Wintaroo, and 7–10 days earlier than Mulgara.
• Kultarr is a tall, mid-maturity line with market leading biomass and export suitable quality for May sowing.
• Archer and Kingbale produce high biomass and export suitable quality. Archer and Kingbale are suitable for IMI residue (IBS) systems.
• 13008-18 is a promising new line, with improved grain yield and grain quality, being slightly taller and earlier to flower than Bannister. Early dual-purpose data for 13008-18 is encouraging.

Cutting growth stage

Watery ripe (Z71) (when grain is formed but only contains clear, greenish liquid and is not drawing heavily on carbohydrate from photosynthesis or storage) is considered the ideal cutting time for optimising hay yield and achieving quality targets. As the industry looks to optimise hay quality, one option available to growers is to cut the crop before it reaches the watery-ripe stage. Choosing the best cutting time is a careful balance between quality, yield, panicle emergence, current and forecast weather.

NHA trials demonstrated the effect of spring growing conditions on delayed cutting and the subsequent effect on hay quality. In 2020, WA trials at Muresk experienced a drier than average spring. Hay quality and quantity was optimised between panicle emergence (Z59) and Z71. During this growth window, traits such as WSC, ADF, NDF and leaf chlorophyll content plateaued, but then deteriorated as the crop growth progressed beyond Z71. Crude protein progressively reduced following Z59. Further yield increase beyond Z71 was outweighed by lower quality, and profitability fell. Victorian trials at Rupanyup experienced a wetter than average spring, and most oat varieties held hay quality from Z59 through to 14 days after Z71. Yield increased significantly as the crop matured.

Cutting in the Z59 to Z71 window helps minimise curing time before quality starts to rapidly decline. Slight delays in cutting can be tolerated when there is adequate spring moisture and mild conditions.

Spikelets ripen down the panicle, so inspect the top florets to make growth stage cutting decisions. Note however, that panicle emergence and watery ripe growth stage aren’t always sequential, i.e. genetics and environmental conditions influence the degree of panicle emergence prior to the onset of watery ripe.

Effects of grazing

Southern NSW hay crop production typically achieves high yields which may not meet export quality standards, therefore the focus is on supplying domestic dairy markets. Grazing dual purpose oats is common. In NSW crop defoliation trials sown in 2020 and 2021, both very wet, high yielding years, simulated grazing significantly reduced hay yield compared to the control (from 13.5–15.5t/ha ungrazed to 10–11t/ha grazed), however, produced more manageable crop canopies with quality better aligned to the requirements of export hay customers for hay production.

An SA trial at Tarlee in 2020 measured similar responses to grazing on oaten hay crops, reducing hay yield by 2t/ha, with a reduction in plant height and lodging, and finer stems compared to the ungrazed crop.

Gains achieved from grazing crops and potential hay quality improvements will depend on livestock returns and the export price premium over the domestic market at that time.

Target plant density

Southern NSW growers typically sow fodder crops at grain-crop densities, which can be more than 50% lower than what is beneficial in other states (targeting 320 plants/m2). Research evaluated the effect of plant densities ranging from 160–360 plants/m2.

Hay yield responded to the different seasonal conditions.

• In the dry 2019 season, hay yield was maintained across increasing plant density.
• Hay yield increased in the wetter seasons of 2020 and 2021, but only by 1.2t/ha.
• As plant densities increased, stem diameter decreased, improving physical hay quality in all seasons.
• In a more average season, the cost of higher plant densities positive impact on hay yield should offset the cost of sowing extra seed.

To target higher quality oaten hay, set the crop up at the beginning of the season with higher target plant densities than grain-only crops to reduce stem diameter, and other hay quality traits, while also providing a stronger plant base structure to support cut hay off the ground, reducing potential quality losses from slower drying hay windrows or wet soil.

Lodging management using Moddus Evo

Moddus Evo inhibits the formation of gibberellic acid (GA), which promotes cell elongation. It is sometimes used to reduce height of wheat or barley crops grown in higher rainfall or high fertility situations that are prone to lodging.

Trials on oaten hay varieties showed the label rate of 400mL/ha of Moddus Evo applied at Z31–Z32, compared to the control:

• improved straw strength and reduced the lodging risk
• reduced yield and height
• did not change stem diameter when cut at 15cm
• affected panicle emergence for some varieties which could cause curing time issues.

Careful consideration should be given before applying Moddus Evo at the label rate to oats for export hay, as it is hard to predict the likelihood of lodging at Z31 and could cause panicle emergence issues.

A lower (unregistered) trial rate of 200mL/ha of Moddus Evo at Z31–Z32, compared to the control and higher rate of Moddus Evo:

• maintained the benefit of better straw strength and lowered lodging risk
• reduced the risk of yield loss.

Managing panicle emergence using gibberellic acid

In dry seasons, and in low rainfall environments, the panicles of oats can be slow to emerge from the leaf sheath, often only partially emerging prior to the watery ripe growth stage. This results in growers either delaying cutting until they have fully emerged or cutting at the right growth stage with extended curing time due to the biomass contained within the leaf sheath. Both of these scenarios can result in reduced hay quality due to the decline in water soluble carbohydrates and increase in fibre when cutting occurs at the later growth stages, or the increased environmental exposure and potential for weather damage as the hay cures over a longer period of time.

Trials showed application of GA as ProGibb SG at 40g/ha at Z31–Z32, Z37–Z39, or both times, did not improve panicle emergence. Note, ProGibb SG is not registered for use in oaten hay (but is recommended on oats for forage).

• GA elongated the nodes, but it elongated them all, producing taller plants, not just the peduncle.
• There was no adverse effect on hay yield or quality of applying ProGibb SG.
• Later applications (post-flag leaf emergence) of GA may be required, or other growth regulator products, so that effect is only seen on the peduncle.

Plant pathology

Disease surveillance

Disease surveillance conducted across Western Australia and Victoria from 2018 to 2021 showed:

• Septoria avenae blotch was the most common disease in WA (>90% paddocks surveyed)
• RLL is the most common and severe foliar disease in Southeastern Australia
• RLL was detected and confirmed in WA oat crops.

Saprophyte suppression/weather damage trials

Post-cutting hay discoloration due to saprophytes reduces visual quality, suitability for export markets and economic returns. Saprophytes feed on dead and decaying plant tissue, so curing hay provides an ideal environment for colonisation, especially when it coincides with rainfall events.

• Late season strobilurin application reduced the visual quantity of saprophytic fungal growth on the exposed/bleached portion of the windrow (the green portion of the windrow was unaffected), without impacting yield and nutritional quality.
• Strobilurin fungicides were more effective at decreasing saprophytic growth than triazole based chemistries. Strobilurin chemistries all had the same level of impact as each other.
• Applying strobilurins 4 weeks prior to cutting at Z71, was just as effective as applying 3 weeks prior to cutting and provided a wider cutting window while reducing hay residue risk compared to no application.
• Fungicides should be applied to manage the diseases present in-crop, with any additional saprophyte suppression an off-target bonus rather than being for the sole purpose of the application.

Conclusion

Growing oaten hay that meets export quality standards is achieved by choosing high yielding varieties with favourable quality traits, and by managing the crop for with optimal nutrition and disease protection, coupled with timely cutting and curing that maintains this high quality.

Varieties respond similarly to agronomic levers, but by choosing varieties with genetically higher quality traits, their hay quality response to sowing time, higher nitrogen rates that drive biomass and seasonal rainfall patterns, growers will be more likely to meet export quality hay standards.

Understand your hay tests for quality and understand your buyer needs to plan agronomic strategies that help improve or continue to produce a consistent quality product.

Acknowledgements

This research was made possible through the contributions of growers and industry through the support of AgriFutures Australia. Thank you to the partner organisations; Department of Primary Industries and Regional Development, South Australian Research and Development Institute, Agriculture Victoria, New South Wales Department of Primary Industries, Birchip Cropping Group, Hart Field Site group and Intergrain.

References

AgriFutures Export Fodder Program Strategic RD&E Plan 2021–2026 

Producing quality oat hay booklet 

Plant diseases impacting oaten hay production in Australia – a review

Red leather leaf of hay oats disease management guide 

Septoria avenae blotch disease management guide 

Oat stem and leaf (crown) rust disease management guide

Contact details

Alison Frischke
BCG
73 Cumming Ave, Birchip VIC 3453
0429 922 787
alison@bcg.org.au
@BCG_Birchip