Break crops in retained stubble systems in Tasmania

  • SFS_FINAL_LogoRetaining standing stubble resulted in lower poppy establishment, reduced poppy plant size and vigour.
  • High levels of Red-legged earth mite (RLEM) damage may occur to poppies where previous wheat stubble is retained.
  • Windrow burning and burning stubble showed potential as stubble management techniques for better poppy establishment.
  • Faba beans show great promise as an alternative winter crop under irrigation. With a high yield of 7.85 t/ha, and average just below 6t/ha, they could compare favourably with cereal crops for economic benefit.
  • The limitation for Tasmanian growers will be the marketing of the grain. Faba beans are exported to the Middle East for human consumption, but from Tasmania this may not be an option. Development of a local market, most likely for feed, will be critical to the success of the crop.

Stubble retention is gaining momentum is Tasmania, at least for part of the rotation, as growers update their equipment and increase utilisation of irrigation. However  the diversity of cropping, which includes small seed crops such as poppies and broadacre vegetable production, in rotation in grain growing areas, means that conventional cultivation is currently still very much a part of the program.

SFS research: 2014

Wheat stubble management effects on poppy establishment

As part of the GRDC-funded stubble project (BWD00024), the Tasmanian branch of SFS designed field trials to test the viability of retaining stubble prior to seeding poppies – an important cash crop for many Tasmanian growers.

This work will now have significance for Victorian growers as the poppy industry expands in the western districts.

A trial was established at ‘Rokeby’, Cressy in 2014 examining ‘short rotation break crops for managing stubble and soil health’.

The aim of the trial was to evaluate the effects of retaining, burning or cultivating wheat stubble on establishment of poppies sown in July.

Trial treatments included: Windrow burn (Figure 1), Retain standing (Figure 2), Burnt, Cultivated and Grower treatment-also cultivation).

The results (Table 1) showed that retaining stubble had a negative effect on poppy establishment, growth and vigour.

cressy sfs stubble break crops

Figure 1. Windrow burn treatment

sfs cressy stubble break crops 2

Figure 2. Standing stubble treatment

Table 1: Poppy and radish emergence and RLEM presence
 Treatment Poppy/m² Radish/m² RLEM score
Windrow burn 48.6 a 1.8 b 4
Retain/standing 27.3 c 2.2 b 5
Burnt 46.5 a 2.0 b 4
Cultivated 39.7 ab 1.0 b 3
Grower 55.8 a 10.0 a 1
LSD (P=0.05) 9.5 2.4

RLEM ratings: 1 = 1-2 RLEM/m2; 2 = Present on <10% plants no vigour reduction; 3 = Present on 10-50% plants some vigour reduction; 4 = Present on >50% plants vigour reduced; 5 = Present or damage on most plants, significant vigour reduction

Figure 1: Biomass reductions resulting from stubble treatments.

Figure 3: Biomass reductions resulting from stubble treatments.

Irrigated faba beans in Tasmania

Faba beans are one of the most water-logging tolerant grain legume species (Solaiman et al. 2007), as well as being tolerant of acid sub-soils, which should make them an ideal crop choice for Tasmanian conditions.

They are also relatively frost tolerant and respond well to cool spring conditions for pod-fill (Agriculture Victoria 20132), but they have not been popular, mostly due to the inherent susceptibility to disease and availability of other more valuable crop species, such as poppies.

New, more disease-resistant (common diseases chocolate spot and ascochyta blight), varieties have recently been released, making this a good time to test them in Tasmanian conditions.

Two trials were established on 13 May 2015 under irrigation at Cressy, to test faba bean variety yield response to fungicide regimes and establishment rate.

Results

Yields achieved were considerably higher than the target yield of 5t/ha with the exception of plots established at 10 plants/m².

The management decision that had the greatest effect on yield was seeding rate (Figure 4).

PBA Samira established at 30 plants/m² yielded 7.85 t/ha, significantly higher than any other treatment. The next highest yielding variety was Nura, with 6.65 t/ha established at 25 plants/m² in the fungicide management trial (Table 1).

These results suggest that growers should target higher seeding rates under irrigation, and we may not have found the ceiling for optimum seeding rate yet.

Figure 3. Varietal yield responses to plant establishment rate. LSD (P=0.05) 1.36t/ha

Figure 4. Varietal yield responses to plant establishment rate. LSD (P=0.05) 1.36t/ha

Table 2. Fungicide regime and variety effect on yield.

Yield Early disease
(9 Sep)
Late disease
(7 Oct)
t/ha severity (1-10) % infect
Variety effect
PBA Zahra 6.12 3.6 1.1a
PBA Rana 5.46 2.4 0.6b
Nura 6.66 2.3 0.8a

Disease

Disease levels in the trials were very low during the 2015 season. There was therefore no significant difference in disease control between fungicide treatments, but a slight variety effect was recorded with PBA Zahra and Nura being more susceptible to chocolate spot infection (Table 1).

Conclusion

Faba beans showed great promise as an alternative winter crop under irrigation.

Figure 4: Faba bean root mass and plant nodulation as at September 18, 2015.

Figure 4: Faba bean root mass and plant nodulation as at September 18, 2015.

With a high yield of 7.85 t/ha, and average just below 6t/ha, they could compare favourably with cereal crops for economic benefit.

  • PBA Samira had the highest yield under irrigation at Cressy focus site.
  • Nura and new variety PBA Zahra also showed promise.
  • Establishment rate of 30 plants/m2 resulted in highest yield.
  • Low disease pressure meant that there was no significant difference between a moderate and intensive fungicide program.

The limitation for Tasmanian growers will be the marketing of the grain. Faba beans are exported to the Middle East for human consumption, but from Tasmania this may not be an option. Development of a local market, most likely for feed, will be critical to the success of the crop.

For more information on current and future trial work in Tasmania, please contact Heather Cosgriff on 0488 600 722.

By  Heather Cosgriff
Tasmanian project & trials manager
E: hcosgriff@sfs.org.au

This research is GRDCLogoStacked_TM_CMYKbeing conducted by BCG as part of the GRDC Maintaining profitable farming systems with retained stubble initiative (project BWD00024 ‘Maintaining profitable farming systems with retained stubble in Victoria and Tasmania’).

Disclaimer: Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Birchip Cropping Group (BCG) or the Grains Research and Development Corporation (GRDC). No person should act on the basis of the contents of this publication without first obtaining specific, independent professional advice. BCG and GRDC and contributors to these guidelines may identify products by proprietary or trade names to help readers identify particular types of products. We do not endorse or recommend the products of any manufacturer referred to. Other products may perform as well as or better than those specifically referred to. BCG and GRDC will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information in this publication. 
Stubble project overview: This guideline has been developed for BCG Farming Systems Group as part of the Maintaining Profitable Farming Systems with Retained Stubble initiative, funded by the Grains Research and Development Corporation (GRDC). The initiative involves farming systems groups in Victoria, South Australia, southern and central New South Wales and Tasmania collaborating with research organisation’s and agribusiness to explore and address issues for growers that impact the profitability of cropping systems with stubble, including pests, diseases, weeds, nutrition and the physical aspects of sowing and establishing crops in heavy residues.
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2 Responses to Break crops in retained stubble systems in Tasmania

  1. Pingback: Break crops in retained stubble systems in south west Victoria | The stubble project: Victoria and Tasmania

  2. Pingback: Break crops in retained stubble systems | The stubble project: Victoria and Tasmania

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