Take Home Messages
- In 2022, which was characterised by a wet spring, mid-quick Koorabup and longer season varieties Kingbale, Wintaroo and Wallaby had the highest hay yields when cut at the watery ripe growth stage.
- Increasing oaten hay plant density can promote finer stems but may not increase hay yields.
- 60kg of applied N has been sufficient to maximise hay yields when soil N levels are >70–80kg N/ha. Higher rates may be beneficial when soil N levels are low or wanting to reserve soil N for the following crop.
- Research has shown hay quality is maintained for longer as hay crops mature in soft,wet springs compared to dry finishes.
Background
Preferred hay quality characteristics — visual, physical and chemical — and their target values, vary widely due to buyer and customer demand differences. Careful planning and attention to hay crop agronomy, testing hay quality and understanding buyer needs, are central to achieving the parameters sought for the desired appearance, nutrient content and subsequent livestock intake required by target markets.
We know how to maximise hay biomass using a range of management tools, but until recently we knew less about the effect of those yield drivers on hay quality, particularly for newer varieties.
For the past four seasons, the AgriFutures Export Fodder Program has been supporting National Hay Agronomy research across Australia to develop our understanding of how the different agronomic levers affect oaten hay yield and quality. Additional research has been supported by BCG members through their membership.
In Victoria, BCG hosted agronomy trials at Kalkee, Rupanyup, Curyo and Wallup. Results from 2022 at Nullawil (available at time of reporting) and summarised findings from the 2019–2021 trials are discussed.
Aim
To evaluate how yield and quality of oaten hay are affected by:
- Variety and plant growth stage at cutting
- Sowing rate
- Nitrogen (N) rate and application timing
Paddock Details
Location: Nullawil
Crop year rainfall (Nov–Oct): 497mm (decile 10)
GSR (Apr–Oct): 384mm (decile 10)
Soil type: Sandy clay
Paddock history: Lentils
Trial Details
Treatments:
Variety x Cutting growth stage
- Variety: Archer, Bannister, Brusher, Kingbale, Koorabup, Kultarr, Mulgara, Rakali, Wallaby, Wintaroo, Yallara, Intergrain breeding line 13008-18
- Cutting growth stages: GS61, GS71
Variety x Plant density
- Variety: Mulgara, Yallara
- Plant density: 120, 220, 320 plants/m2
N rate
- N rate: 20, 30, 40, 60, 90 kg N/ha
N timing x rate
- Application timings: all upfront, standard hay (2/3 upfront, 1/3 6 weeks after sowing (6WAS)), late application (1/3 upfront, 2/3 at GS31), very late application (1/3 upfront, 2/3 at GS37–39)
- N rates: 60, 90 kg N/ha
Target plant density: 320 plants/m², unless specified otherwise
Seeding equipment: Knife points, press wheels, 30cm row spacing (+ splitter boot (70mm split))
Sowing date: 9 May 2022
Replicates:
- Variety x growth stage and Variety x plant density trials: 4
- N rate and N timing x rate trials: 3
Hay cutting: 15 September – 4 October 2022
Trial average yield: GS61 4.5t/ha, GS71 6.4t/ha
Trial Inputs
Fertiliser:
- All treatments received Granulock® Supreme Z + Flutriafol (400mL/100kg) @ 60kg/ha at sowing.
- Variety x growth stage and Variety x plant density treatments were top‑dressed with 120kg/ha of urea at GS13 (3 June).
- N rate and N timing x rate treatments had urea top-dressed at sowing, mid-tillering (6 weeks after sowing), early (GS31) or late (GS37–39) stem elongation, at rates that met the N treatment amounts (as per Table 3).
Trial managed as per best practice for herbicides, insecticides and fungicides.
Method
Replicated field trials were sown with completely randomised designs. Assessments included soil analysis and moisture, plant establishment, NDVI (data not shown), hay biomass at GS61 (V x GS trial only) and GS71 calculated from samples cut and dried in an oven, plant height, lodging, and stem diameter (V x GS and V x PD trials only). NIR (including DairyOne calibration) was being analysed at the time of writing and will be reported once data is available.
Results & Interpretation
2019–2021 results: Trial reports for 2019, 2020 and 2021 research can be found in the corresponding year of BCG Season Research Results.
2022 results: Measured in March, plant available water was 91mm and soil N to 1m was 80kg N/ha.
The 2022 growing season at Nullawil began after 39mm rain fell in the second half of April, though little rain fell in the week before sowing on 9 May. Trials established evenly, but became moisture limited on the clay soil during winter. This stress was visible in the trial with leaf tipping across all varieties. For the first four months, rainfall was recorded frequently, but only eight rain events exceeded 4mm. From 8 September, conditions improved, becoming very wet with regular rainfall for the rest of the month.
Crops recovered well with spring rain and the growing season grew to a decile 10, however hay yields were limited to an average of 6.4t/ha by GS71 due to the timing of the rainfall and moisture stress experienced during winter.
Hay yield was affected by oaten hay variety, growth stage and N timing, but not N rate or sowing rate. Physical hay characteristics were affected by variety, cutting growth stage and plant density.
Variety and growth stage
Hay yield responded to variety and growth stage at cutting time. Despite differences in maturity, all varieties responded similarly to the time of cutting (no interaction effects).
Oat crops cut early at the start of flowering (GS61) averaged 4.5t/ha across varieties but panicles were not fully emerged. Wintaroo and Kingbale yielded highest, closely followed by Wallaby and Kultarr.
Crops cut at the standard cutting time of watery ripe (GS71), when panicles were further emerged, benefited greatly from the delay in cutting date, averaging 6.4t/ha. Hay yield was highest for varieties previously shown to have a slower development speed. These were Wintaroo and Kingbale, Koorabup a mid-maturing variety and the new variety Wallaby, which all yielded 7t/ha or more at GS71 (Figure 1). Kultarr, Brusher and Yallara also yielded similarly, achieving more than 6.5t/ha.
Plant height was influenced by both variety and cutting growth stage, with varieties responding differently to the cutting growth stage. At GS61 Kingbale and Wintaroo were noticeably taller than other varieties, reaching 74cm, then Brusher grew quickly to reach a similar height by GS71, with Kingbale reaching 98cm, Wintaroo 94cm and Brusher 92cm.
Kingbale and Wintaroo also had wider stem diameter, but Brusher was 0.5cm finer. Stem width was influenced by cutting growth stage (P<0.001), widening on average from 3.9mm at GS61 to 4.4mm by GS71. Stem widths of all varieties responded similarly to cutting time (no interaction), and were of good quality at less than 6mm (Table 1).
Plant density
Mulgara and Yallara were sown at the recommended plant density for hay of 320 plants/m2 and compared to medium and lower densities at 220 plants/m2 and 120 plants/m2. The corresponding sowing rates are shown in Table 2.
For both varieties, establishment counts achieved the target plant density for lower densities 120/m2 and 220/m2 but didn’t quite reach the desired plant density of 320 plants/m2, possibly due to greater competition for moisture after sowing (Figure 2).
Groundcover
Groundcover from the different cereal crops and pastures in all plots was 100 per cent in October, covering plots with varying amounts of biomass and composition of plant material. Breakdown rates of crop and pasture residues are enhanced by nitrogen content, and contact with the soil, so cereal residues generally take longer to break down than legume residues. Depending on when and how standing crops are grazed, the volumes of biomass show great potential for providing greater groundcover over summer months, when other pastures have senesced or have been chemically fallowed.
Plants compensated for lower plant densities with no plant density effect on hay yield, averaging 5.8t/ha across the different sowing rates.
As plant density changed from 120 plants/m2 to 220 plants/m2, stems became 5.7cm shorter and 0.5cm finer. Since establishment didn’t reach the desired target plant density for the higher sowing rate, there were no further changes to plant height or stem diameter at the highest sowing rate.
Nitrogen rate and timing
Nitrogen rate
There was no response in oaten hay biomass or plant height to increasing N rates from 20 to 90kg/ha applied to Mulgara in 2022.
This is unsurprising due to the moisture stress experienced during stem elongation limiting hay yields and N mineralisation during winter. The crop was unlikely to have been nitrogen limited as the available soil N in March was 80kg N/ha to a depth of 1m following a relatively poor lentil crop in 2021, although rain in April could have mineralised further N before sowing.
Nitrogen rate and timing
There were no differences in hay yields when the 60 or 90kg N/ha rates were applied to Mulgara, but there was a hay yield response to the application timing (Table 3).
Applying N at the start of stem elongation offered a yield benefit over applying it all upfront, likely due to the timing of in-season rainfall. Applying N very late (flag leaf emergence) didn’t offer a yield benefit, but we are interested to see if delaying the in-crop N application can change the protein quality of hay.
There were no plant height responses to N treatments and stem thickness was not measured due to funding limitations.
Commercial practice
To determine hay quality, visual indicators such as hay colour, stem thickness, texture and smell, are combined with feed testing measures to determine palatability, animal intake and performance.
Generally, high quality hay has soft textured, thin stems (<6mm), with high water-soluble carbohydrates (WSC) >22%, crude protein (CP) >4–10%, metabolisable energy (ME) >9.5 MJ ME/kg DM, and is low in fibre (require NDF <50–57% and ADF <27–35%).
The following summarises some of the key lessons about varieties and agronomic levers on hay quality relevant to Victorian growers from the National Hay Agronomy research conducted across 2019 to 2022.
Variety
- Dual-purpose variety Yallara (quick) was the best performing of 10 varieties, with comparable hay yield to the specialist hay varieties, Brusher (quick) and Wintaroo (mid maturing), but better quality. Yallara had the highest WSC and lowest ADF and NDF fibre levels, combined with thin stems. Note, as you head south from the southern Mallee to the medium rainfall Wimmera, Yallara becomes a bit too quick in better seasons.
- The new specialist hay variety, Koorabup (mid-quick), was generally disappointing when benchmarked against Brusher, yielding 0.5t/ha lower, and a higher ADF and NDF risk, lower WSC, but similar hay greenness and stem diameter.
- The release of Imi-tolerant varieties Kingbale (mid-slow) and Archer (mid) has offered oaten hay growers an option for weed control for brome and barley grass (IBS application only), or to sow into stubble containing Imi-residues.
- Other new hay varieties to watch include Kultarr (quick-mid) and Wallaby (mid-slow). Kultarr offers a taller height for the lower-rainfall regions whilst Wallaby has shown consistent high quality and maintains good yields.
- Hay quality was high across all varieties and seasons in Victoria and South Australia, but was more variable in other regions where large yields and fibrous stems reduced quality.
Time of sowing
- In general, earlier sowing increased the crop water use efficiency and opportunity to maximise hay yields, but does not always maximise hay quality.
- Variety response to sowing date was variable and not easily predicted before the season started or when the crop was planted.
- In a season with a dry spring, crops sown earlier yielded higher, with faster varieties Brusher, Mulgara, Yallara, and the mid-maturing Wintaroo yielding better
- For good spring years, delaying sowing until the end of May grew more hay when autumn was wet but winter was dry. However, if autumn was dry but the winter was wet, the time of sowing did not affect hay yield. In a season with a softer spring, longer season varieties like Wintaroo performed better.
- Due to variable seasons and inconsistencies between years, conclusions about the variety and sowing date interactions on hay quality were hard to make.
Time of sowing
- Nitrogen drives more biomass, taller plants, and can increase the risk of lodging in susceptible regions and seasons.
- Varieties responded the same to changing N (0–150kg N/ha) rates, across a range of seasons.
- The tipping point for yield was 90N across Australia, although 60N was adequate when sites received below-average rain during critical periods, or if soil N was >80kg N/ha.
- The season and variety were generally a larger factor in determining hay quality than the rate of N applied, except for CP which increased, and WSC which decreased with increasing N.
- Applying more than 90kg N/ha increased the risk of not meeting industry WSC limits for premium hay of more than 22 per cent. Fortunately, in Victorian trials >90kg N/ha dropped WSC but it still remained >25 per cent.
- Protein rose with increasing N rate from about 5.5 to 8.5 per cent — this is still in livestock maintenance range at higher N levels.
- Even though varieties responded the same, variety choice still determines how much N can be applied. Varieties with the highest inherent hay quality will allow you to maximise hay yield and returns driven by higher fertiliser N rates. Planting varieties with lower hay quality, particularly WSC, limits how much N can be applied before quality drops and discounting occurs.
- N management requires early decisions — understand soil moisture and soil N at sowing to decide on an appropriate rate. The least risk N strategy for hay is to sow with starter N and then by six weeks being able to respond with in-crop N (two-thirds at sowing, one-third in-crop) to a seasonal outlook that is hopefully increasing in confidence.
Time of sowing
- At watery ripe, GS71 is considered the ideal cutting time for optimising yield and achieving quality targets for cereal hay. In reality, considering logistics and weather, it can be challenging to cut hay at exactly GS71. 2022 was a perfect example where weather conditions stopped some growers accessing paddocks for cutting on time.
- From trials in 2020 we found if spring growing conditions became water limited, WSC, ADF, NDF and leaf chlorophyll were maintained between GS59 (full panicle emergence) and GS71, but deteriorated as crops matured past GS71. CP declined progressively after growth stage Z59. Waiting for the increase in yield can be outweighed by lower quality, causing overall return per hectare to fall.
- Quality didn’t decline as rapidly past GS71 if spring conditions were wet and mild.
- Aim to cut after full head emergence GS59 and by watery ripe GS71. Cutting in this window helps minimise curing time before quality starts to rapidly decline. Cutting before full head emergence, as occurred in 2022 for the GS61 cut (when the panicles had started flowering), can lead to increased curing time due to moisture pockets when panicles are stuck in the boot.
Time of sowing
- To target higher quality oaten hay, the crop should be set up at the beginning of the season with higher target plant densities than grain-only crops.
- As plant density increases, hay yield is maintained or may improve, and stem diameter can reduce improving quality. Both responses depend on the seasonal conditions, however our trials have not shown reductions in yield or quality with increasing plant density.
References
Frischke A., Clarke G., and Jackson S., 2022, 2021 BCG Season Research Results, ‘Oaten Hay Agronomy – Wimmera 2021’, pp. 85–92.
Frischke A., Clarke G., and Troup G., 2021, 2020 BCG Season Research Results, ‘Oaten Hay Agronomy – Wimmera’, pp. 177–184.
Frischke A., Clarke G., and Troup G., 2020, 2019 BCG Season Research Results, ‘National Hay Agronomy – What variety, when to sow and what N rate to use?’, pp. 50–54.
Acknowledgements
This research was part of the ‘National Hay Agronomy project’ extension year, funded by the AgriFutures™ Export Fodder Program. It is a southern Australia collaboration between South Australian Research and Development Institute (SARDI), BCG and the Hart Field Site Group.
The sowing rate trial was supported by BCG members through their membership.
Results summarised in the Commercial Practice section were from the ‘National Hay Agronomy’ project PRJ 011029 funded by the AgriFutures™ Export Fodder Program. This was a collaboration between the Department of Primary Industries and Regional Development (DPIRD) in WA, South Australian Research and Development Institute (SARDI), Agriculture Victoria, New South Wales Department of Primary Industries (NSW DPI) and grower groups BCG and Hart Field Site.
