Lessons for growers from the Hyper Yielding Crops (HYC) and High Rainfall Zone (HRZ) Farming Systems projects in Western Australia

Key messages

• Ameliorated sandplain soils deep ripped to 800mm increased wheat yield by approximately 0.5t/ha at a cost benefit ratio of just less than $2 return for every $1 spent.
• Winter wheat cultivars extend the ability to sow early (early – mid April) on large acreages, however, with yields of 6-8t/ha (2020 & 2021) the HRZ project has to date shown no difference in yield between the best winter and spring cultivars on ameliorated soil in a frost-free environment.
• Increased inputs, particularly nutrition have been the key to cost effective yield increases in wheat trials over the last two seasons, while in barley both disease management and nutrition hold the key to higher output in seasons of higher yield potential.
• The principles of canopy management are more applicable to the increased yield potentials of ameliorated soils and to maximise crop yields in the better seasons of the WA HRZ.

Hyper yielding crops research and WA HRZ farming systems project – project objectives

Led by Field Applied Research (FAR) Australia, the Hyper Yielding Crops (HYC) project is a Grains Research and Development Corporation (GRDC) national initiative which aims to push the economically attainable yield boundaries of wheat, barley and canola in those regions with higher yield potential. In WA, the project team is working on barley at Frankland River in the Albany Port Zone. The WA HRZ farming systems project is a GRDC multi-agency (DPIRD, FAR Australia, CSIRO) investment that aims to reduce the gap between current and potential yield in wheat and canola in WA’s HRZ. The concept of the cereal research programme for the HRZ project is to explore the productivity and profitability of cereal crops (primarily wheat) sown in mid-April (16 April) as part of a soil ameliorated farming system. This research is primarily being conducted on sandplain in the Esperance region with a small site at Frankland River.

Soil amelioration and crop establishment

Results from the HRZ project in 2020 and 2021 illustrated that there was a significant yield advantage of 0.45 & 0.47 t/ha respectively to deep ripping to a depth of 800mm on a sandplain soil prior to establishing wheat. With ripping costed at $80/ha and grain at $310/t soil amelioration produced an approximate return of just under $2 for each $ spent (assuming benefits were only apparent for one year). Spade seeding superimposed on deep ripping (costing approximately $140/ha) generated higher yields (0.69t/ha) than deep ripping alone but was less responsive to higher levels of nutrition input (both extra N and extra NPKS), indicating that spade seeded crops had access to greater nutrient availability without the need for the increased fertiliser input (Table 1).

Using management to build and protect high yielding crops in wet environments (seasons)

Canopy management is a broad term but fundamentally relies upon adopting techniques that allow crops to intercept more radiation (sunlight) and transpire more water into biomass at the time in the season that contributes to yield. This is first achieved by ensuring flowering is matched to environment (optimally for WA HRZ mid-September) and second by ensuring that a high proportion of the upper crop canopy leaves remain intercepting light (retain green leaf area, disease control) during the ‘critical period’ for grain number formation (month before flowering in cereals). Unlike low rainfall environments, excessive growth before stem elongation can be unproductive and lead to lodging, shading and poor light interception in the critical period. Equally nitrogen (N) limitation, and/or poor disease control during this period will lower grain number potential and yield either by limiting biomass production or its conversion into yield (harvest index). Harvest indices of 50% or slightly higher should be possible with good management, so to achieve 10t/ha cereal grain yields the final biomass needs to be greater than 20t/ha. In 2021, where crops stayed free of frost and waterlogging, the project team could explore higher yields in WA. So, what are we achieving in our cereal projects in WA in terms of wheat grain yields and final harvest dry matters (Figure 1)?

While canopy management techniques can improve harvest index, they should not be done at the expense of reduced final biomass. For example, grazing (mowing) spring and winter wheats has been noted to increase harvest index (HI) at some of the HYC trial sites (e.g., Wallendbeen, NSW) but grain yields were not increased due to lower final dry matter at harvest. Effects of grazing on HI in WA cereal trials have been largely neutral. Equally, increases in dry matter at harvest associated with late developing wheats that spend too long in the vegetative period and have flowering windows past the optimum for the region do not maximise grain yield. For example, at Esperance, RGT Accroc PBR Symbol (a red grained feed wheat) flowered in mid-October and had a harvest index of 30% (Figure 1 & Table 2).  In contrast, at Frankland River where grain yields were higher, RGT Accroc PBR Symbo was able to translate a greater proportion of its harvest dry matter into higher grain yield with an HI of 39% (Table 3).

Although APSIM modelling of the Esperance research site clearly shows a yield advantage to sowing winter wheat over spring wheat in mid-April, trial results to date have indicated no difference in yield in this relatively frost-free environment. This is despite spring wheats flowering in August prior to the recognised optimal flowering window of mid-September. Similar findings have been observed at the Frankland site (which did not suffer frost or waterlogging) where Rockstar (spring wheat) and Illabo (winter wheat) both yielded just under 9t/ha from a 29 April sowing (Table 3).  Side by side trials planted on the same day at Esperance research centre in mid-April have shown no yield advantage to winter wheat cultivars over spring wheats sown in mid-May. Despite achieving similar yields to spring wheats, low harvest indices have been a consistent theme with winter genetics that are not as well adapted to the environment. Breeding efforts for WA have historically focussed on spring wheats that have been selected for a higher harvest index and faster development that suit WA’s shorter grain filling period (relative to the HRZs in other states). While management can improve HI to some extent, it is likely that quicker winter types and more breeding selection are required to improve this metric in WA before some of the modelled yields can be realised in winter wheats.

Hyper Yielding barley crops – importance of disease management to maximise yield potential in barley

The importance of disease management in keeping the upper canopy leaves free of infection in both the critical period four weeks before flowering and during grain fill was observed in barley research at both the Frankland and Esperance sites. RGT Planet and Rosalind PBR Symbol have been consistently high yielding cultivars in most high rainfall zones of Australia, particularly those like WA where the season is slightly shorter and subject to higher temperatures during grain fill. While new germplasm introductions such as winter cultivars show promise in the cooler climate HRZ’s they still are not stable in yield and are more vulnerable to lodging and head loss. Under high disease pressure and with poor disease management other spring cultivars (such as Laperouse PBR Symbol) can yield similar or higher than RGT Planet PBR Symbol but do not always have the same yield potential when disease is managed. Improving yield in RGT Planet PBR Symbol relies upon effective disease control with robust fungicide regimes and highlights the need for growers to consider carefully when better chemistries such as the SDHI’s are applied to maximise yield response and to manage fungicide resistance. The need for higher fungicide input in Planet PBR Symbol was observed at both Esperance and Frankland in 2021. In Esperance in the WA HRZ farming systems project, barley yields matched and exceeded those of wheat sown at the same time. Laperouse PBR Symbol was significantly higher yielding than Planet PBR Symbol under a standard fungicide input, but under a high input fungicide strategy, including SDHI and strobilurin chemistry, yields of both were higher at 8t/ha with no difference between the two cultivars (Table 4).

Even at Green Range in 2020, in the absence of significant disease pressure, a more robust fungicide strategy increased barley yield. At Frankland River in 2021, in RGT Planet PBR Symbol, shifting from two relatively modest triazole applications to three fungicides (including an SDHI seed treatment and strobilurin chemistry) increased yield from 6.1t/ha to 6.9t/ha. When combined with other management factors such as plant growth regulation, yield was increased to 7.1t/ha (1t/ha total increase compared to standard management), and then when additional nitrogen was applied to this system (to take account of increased yield potential) yields increased to 7.4t/ha, a 1.3t/ha yield increase relative to what is considered standard management (Figure 2).

Other management is important and compliments disease management, for example Rosalind barley yield ranged from 6.0t/ha in the standard management system to 7.4t/ha in the hyper yielding system, however this was due to increased N and PGR application, and there was no difference between the fungicide regimes. This also highlights the effectiveness of improved varietal disease resistance. In other winter cultivars such as Pixel PBR Symbol and Madness PBR Symbol, which have far superior disease resistance, there was no influence of any of these management factors and flowering was too late to realise their yield potential in WA. It’s unlikely these winter cultivars will ever be adopted in WA until a faster developing winter type is developed.

Investment acknowledgement

FAR Australia gratefully acknowledges the investment of the Grains Research and Development Corporation (GRDC) for the Hyper Yielding Crops Project which is a national initiative and the WA HRZ Farming Systems project which is a regional WA project.

Collaborating partners acknowledgement

FAR Australia gratefully acknowledges the support of all its research and extension partners in the Hyper Yielding Crops project. These are CSIRO, the Department of Primary Industries and Regional Development (DPIRD) in WA, Brill Ag, Southern Farming Systems (SFS), Techcrop, the Centre for eResearch and Digital Innovation (CeRDI) at Federation University Australia, MacKillop Farm Management Group (MFMG), Riverine Plains Inc and Stirling to Coast Farmers. We would also like to thank our host farmer in WA Kellie Shields, Donald Pentz and Terry Scott

Field Applied Research (FAR) Australia gratefully acknowledges the support of project partners DPIRD and CSIRO in the WA HRZ Farming Systems project and the input of the Whiting Family in managing the research site at Esperance and Kellie Shields, Donald Pentz and Terry Scott in managing the research site at Frankland River.

Contact details

Name: Nick Poole, Kenton Porker and James Rollason (FAR Australia) and Jeremy Curry (DPIRD)
Business Address: Shed 2/63 Holder Rd, Bannockburn, Victoria 3331
Phone: 08 5266 1290 / 0499 888 066
Email: nick.poole@faraustralia.com.au, kenton.porker@faraustralia.com.au, james.rollason@faraustralia.com.au, Jeremy.Curry@dpird.wa.gov.au

Varieties displaying PBR Symbol beside them are protected under the Plant Breeders Rights Act 1994