Take home messages

• With planning and consideration given to match crop type and variety with the farming system, yield of pulses can be improved.
• Agronomy practices such as early sowing can offer opportunities to increase productivity in faba bean and lentil.
• Herbicide choice, rate, and application timing is important, particularly with lentil in order to reduce the risk associated with crop damage.
• An important consideration to achieving success with pulse crops is a good disease management strategy. The best approach is integrated disease management.

Background

Pulse production has continued to expand on the Eyre Peninsula, with high grain prices and the need for crop diversification driving this expansion. These crops are considered a cash crop rather than being utilised solely for their break crop benefits. As such, there is a need to understand strategies to improve crop yield and yield stability. In such dryland farming systems, improving crop yields can be achieved through improved breeding and agronomy. When considering agronomic crop management, several strategies can be considered to achieve improved yields including variety selection, sowing date, density, both pre-crop and in-crop pest management, and harvest timing. This paper describes some agronomic opportunities to improve yield in pulses.

Pulse performance on the lower Eyre Peninsula and agronomic opportunities

Historic yield performance demonstrates the variability of outcomes for faba bean, lentil, field pea and lupin on the lower Eyre Peninsula (Figure 1). Variability is to be expected when considering the level of seasonal variation experienced in dryland farming, however the variation also demonstrates there is a lot of unrealised yield potential for faba bean, lentil, and field pea particularly.

Species and variety selection

One of the starting points is variety selection. When selecting suitable varieties, it is important to consider the agronomic characteristics and how these match the local climate, soil type, paddock history, disease risk profile, and agronomic management. The South Australian Crop Sowing Guide is a good resource for this information and is updated annually (https://www.pir.sa.gov.au/__data/assets/pdf_file/0019/335602/grdc-2022-sowing-guide-sa.pdf). Increasingly, variety selection is influenced by the use of residual herbicides in the preceding crops, and the desire for in-season broadleaf weed control using an imidazolinone (IMI) herbicide. This is an important consideration due to the risk of herbicide damage and resulting yield reductions in sensitive species and varieties. Currently options are available in lentil, faba bean and field pea.

Figure 1. Variability of grain yields (t/ha) of A. faba bean, B. lentil, C. field pea, D. lupin from research and demonstration trials on the lower Eyre Peninsula. Data compiled from NVT and agronomic field trials 2016 to 2021.

Achieving yield gains with early time of sowing (ToS)

The next decision point is often the sowing time of the crop. Recent research has demonstrated the potential to achieve yield advantages through very early sowing of pulse crops. There is a consistent response to early sowing for faba bean in the medium rainfall zones, providing that there is an early season break or adequate soil moisture for early crop establishment (Roberts et al. 2019, Bruce et al. 2022a, Day et al. 2021). Grain yield advantages have been achieved at Tooligie in 2020 (Figure 2), and average grain yield increases of 21% and 12% were achieved for early sowing in each of 2020 and 2021 at Warnertown (Figures 3 and 4). However, selecting faba bean varieties to match time of sowing is important. The greatest yield response was seen in PBA Marne, a variety adapted to low rainfall, short growing seasons, and early sowing opportunities. In contrast, the popular mid-flowering variety PBA Samira has shown greater yield stability across all times of sowing (Roberts et al. 2019), with no or a small yield advantage from early sowing. Lentil can also be responsive to early sowing in the absence of substantial reproductive frost events. Early sowing benefits were not realised at Tooligie in 2020 (Figure 2), a site that experienced frost, while in the lower-risk frost environment at Warnertown, average lentil yield increases of 26% and 20% were achieved for 2020 and 2021 (Figures 3 and 4).

Early sowing limits opportunities for effective weed control by restricting the pre-sowing window for an effective herbicide knockdown. In these circumstances, paddocks with low weed burdens should be chosen, along with selecting varieties with improved herbicide tolerance traits, as pulses are generally poor competitors with weeds. Additionally, disease management requires particular attention when sowing early in average to wet seasons. It is well known that disease pressure and intensity is favoured by early sowing, which generally produces excessive early growth. Management options to combat this include maintaining sound crop rotations and farming practices, such as using varieties with the best-known disease resistance, choosing more erect varieties, and using disease-free seed.

Figure 2.Grain yield (t/ha) response of wheat, faba bean and lentil to different times of sowing (ToS 1 = 2 Apr, ToS 2 = 6 May) at Tooligie, 2020. Error bars represent standard error (P<0.05).

Figure 3. Grain yield (t/ha) response of wheat, lentil and faba bean to different times of sowing at Warnertown, 2020. Error bars represent standard error (P<0.05).

Figure 4. Grain yield (t/ha) response of wheat, lentil and faba bean to different times of sowing (ToS 1 = 30 Mar, ToS 2 = 11 May) at Warnertown, 2021. Error bars represent standard error (P<0.05).

Herbicide choice and timing

Herbicide choice, rate, and application timing is important particularly with lentil in order to reduce the risk associated with crop damage. Lentil is extremely sensitive to Group 5 (previously Group C) herbicide use in dry conditions. Applying herbicide and incorporating by sowing (IBS) is considered a lower risk option than a post-sowing pre-emergent (PSPE) application. Herbicide application IBS will disperse the herbicide so that it does not sit close to the seed, thereby reducing risk of crop injury. In contrast, herbicides applied PSPE can leach into the seed bed in low rainfall environments with the first rainfall event post-application. It is important to follow all label rates and directions for use to minimise risk of crop injury. Crop injury from herbicides can result in reduced nitrogen fixation, more weed competition, reduced grain yields, and increase the risk of soil erosion over summer.

Broadleaf weed control options have expanded with the availability of Reflex® (Group 14; previously Group G), particularly for the control of weed populations that have developed resistance to imidazolinone (IMI) herbicides. It is important to understand the interaction between Reflex and Group 5 chemicals with specific soil types prior to using this product. Greater crop injury has been observed in alkaline soils compared to acidic sands (Bruce et al. 2022b).

Key outcomes from the first year of grass weeds research at Tooligie has found the new Group 23 herbicide Ultro® (active carbetamide) and commonly used Group 3 propyzamide proved equally effective for ryegrass and barley grass control in lentil.

Disease management

Another important consideration to achieving success with pulse crops is a good disease management strategy. Disease management strategies are based on the variety resistance rating, the disease, and the disease risk depending on seasonal conditions and intensity of production in that region. The best approach to disease management is integrated disease management, combining selection of a resistant variety, use of clean seed, paddock hygiene, application of seed dressings if recommended for that species, regular monitoring of the crop for disease, and the application of fungicides during reproductive growth stages to protect developing grain. It is important to implement a three to four year break between crops of the same type, revise variety selections and avoid sowing in paddock(s) in close proximity to the previous year’s crops (Blake et al. 2019). Crop sowing guides and GRDC Grow Notes provide key information on variety resistance characteristics and disease management approaches.

Conclusion

Pulse agronomy research and validation field experiments are continuing across South Australia with the aim to refine agronomic strategies for each rainfall zone, drive and support the continued expansion of areas grown to pulses and close the current yield gap. We will continue to see agronomic strategies refined, new varieties released to the market, and new herbicide tolerance traits becoming available in pulses. For this reason, it is important to stay up to date with pulse agronomic and variety information, and to evaluate variety selection each season to ensure the greatest yield potential. Be vigilant with disease monitoring and ensure fungicide applications are made ahead of rain events to minimise the spread of disease spores. Ensure herbicide label rates and directions for use are followed to reduce risk of crop injury. With careful and considered planning and management, pulse crops can be a profitable option for growers on the lower Eyre Peninsula.

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers through both trial cooperation and the support of the GRDC, the authors would like to thank them for their continued support. Research reported in this paper was also funded by Upper North Farming Systems Group and SARDI, and the authors would like to acknowledge these important investments.

References

Blake S, Farquharson L, Kimber R, Davidson J, Walela C, Hobson K (2019) Ascochyta blight in intensive cropping of pulses. Proceedings GRDC Grains Research Update, Adelaide, February 2019, p. 39.

Bruce D, Roberts P, Day S, McMurray L, Walela C (2022) Flipping the script on the 'failure bean' story: faba bean out-yielding in early sown opportunities. 20th Australian Agronomy Conference, Toowoomba.

Bruce J, Aggarwal N, Sherriff S, Trengove S, Roberts P (2021) Crop safety and broadleaf weed control implications for various herbicides and combinations in lentil. Eyre Peninsula Farming Systems Summary 2021, SARDI. Minnipa, South Australia, pp.126–132.

Day S, Roberts P, Gutsche A (2021) Low rainfall pulse production – one pulse does not fit all. Proceedings GRDC Grains Research Updates, Wudinna, July 2021, pp. 39–46.

Roberts P, Walela C, McMurray L, Oakey H (2019) South Australian pulse research update – multi-season results. Proceedings GRDC Grains Research Update, Adelaide, February 2019, pp. 49–54.

Contact details

Penny Roberts
SARDI
70 Farrell Flat Rd (PO Box 1078), Clare SA 5453
0436 678 982
Penny.Roberts@sa.gov.au
@PennyRo25927708