The 10 key lessons from the Optimised Canola Profitability project

Take home messages

  • Lesson 1: Crop planning and preparation.
  • Lesson 2: Variety selection.
  • Lesson 3: Matching varietal phenology with sowing time.
  • Lesson 4: Sow slow spring canola late March to mid-April.
  • Lesson 5: Sow mid spring canola mid-April to early-May.
  • Lesson 6: Sow fast spring canola late April to mid-May.
  • Lesson 7: Apply post sowing nutrition as required.
  • Lesson 8: Understand the critical growth period.
  • Lesson 9: Harvest management.
  • Lesson 10: Evaluate financial performance.

Background

Between 2014 and 2019 research to better understand the yield drivers of canola was conducted in southern and eastern Australia through the Optimised Canola Profitability (OCP) project, which is a project supported by a joint investment from CSIRO, NSW DPI and GRDC.

The aim of the project was to improve canola profitability through a better understanding of how phenology and physiology can guide tactical agronomy to improve canola yield and profit in different environments. This research is targeted at low to medium rainfall zones and is a collaboration between CSIRO, NSW DPI and GRDC, in partnership with SARDI, CSU, MSF and BCG (CSP00187). The project links closely with similar GRDC supported projects in Western Australia and in high rainfall zones (HRZ). From southern Queensland, through New South Wales (NSW), and into Victoria (Vic) and across to South Australia (SA) the OCP Project has conducted a range of field experiments and modelling simulations to improve canola profitability in the region.

This article will summarise ten of the key findings in the project, with further information available in the ‘20 tips for profitable canola’ guide found online here: 20 Tips for Profitable Canola in South Australia

Lesson 1: Crop planning and preparation

The two most important factors to consider when selecting paddocks for canola are nitrogen (N) and stored soil water. Growing canola after a pulse crop or long fallow will ensure relatively high N and plant available water (PAW) levels. In the low rainfall zones of SA (Upper Eyre Peninsula, Upper North and Mallee) it is risky to sow canola when either water or N levels are low, and especially when both are low. In South Australian areas with reliable winter and spring rainfall, selecting paddocks with high starting N will increase crop yield potential, especially for hybrid canola varieties.

Lesson 2: Variety selection

There are three key decision areas with variety selection:

1. Varietal phenology.

Each canola variety has a set of triggers that drive its development and control flowering time; thermal time (day degrees), vernalisation (cold) and photoperiod (day length). Each of the development triggers could play a different role in each variety.

2. Breeding type (hybrid or open-pollinated).

Whilst open pollinated (OP) canola varieties dominate much of the area planted in SA (due to reduced seed costs from retaining seed), hybrids are increasing in area as they currently offer a wider range of phenology, herbicide tolerance options, and disease resistance levels, as well as producing higher yields as varieties improve.

3. Herbicide tolerance

It is important to consider the spectrum of weeds (and resistance status) that may need controlling when selecting a canola variety so that the appropriate varietal herbicide tolerance is selected. Canola’s critical role as a break crop for weeds needs to be achieved to maximise benefits of their use.

Table 1. Phenology, maturity, herbicide tolerance and breeding type rating of most of the modern canola varieties.

Variety

Phenology*

Maturity

Herbicide tolerance

Breeding type

(hybrid or OP)

Nuseed Diamond

Fast

Early

Conventional

Hybrid

ATR Stingray

Fast

Early

Triazine

OP

Hyola®350TT

Fast

Early

Triazine

Hybrid

SF Spark TT

Fast*

Early

Triazine

Hybrid

Hyola®506RR

Fast

Mid-early

Roundup Ready

Hybrid

Hyola®580CT

Fast

Mid-early

lmi/Triazine

Hybrid

HyTTec® Trident

Mid-fast

Early

Triazine

Hybrid

Hyola®550TT

Mid-fast*

Mid

Triazine

Hybrid

InVigor®T3510

Mid-fast*

Early to early-mid

Triazine

Hybrid

Banker CL

Mid-fast

Mid

lmidazolinone

Hybrid

InVigor®T4510

Mid-fast

Early-mid

Triazine

Hybrid

Saintly CL®

Mid-fast

Early-mid

lmidazolinone

Hybrid

Pioneer®44T02 (TT)

Mid-fast

Early-mid

Triazine

Hybrid

Hyola®530XT

Mid-fast*

Mid

Truflex/Triazine

Hybrid

XseedTMRaptor

Mid-fast*

Mid-early

Truflex

Hybrid

Hyola®410XX

Mid-fast*

Mid-early

Truflex

Hybrid

ATR Flathead

Mid-fast*

Early

Triazine

OP

ATR Bonito

Mid-fast

Early to early-mid

Triazine

OP

lnVigor® R4022P

Mid-fast*

Mid-early

Truflex

Hybrid

Pioneer®43Y92 (CL)

Mid-fast

Early

lmidazolinone

Hybrid

Pioneer®43Y29 (RR)

Mid-fast*

Early

Roundup Ready

Hybrid

Pioneer®44Y27 (RR)

Mid-fast

Early-mid

Roundup Ready

Hybrid

Pioneer 44Y90 (CL)

Mid-fast

Early-mid

lmidazolinone

Hybrid

ATR Mako

Mid-fast

Mid-early

Triazine

OP

Nuseed Quartz

Mid

Mid to mid-early

Conventional

Hybrid

HyTTec®Trophy

Mid

Early to early-mid

Triazine

Hybrid

Pioneer®45T03 (TT)

Mid

Mid

Triazine

Hybrid

ATR Gem

Mid

Mid-early

Triazine

OP

DG 670TT

Mid

Mid

Triazine

Hybrid

GT-53

Mid

Mid

Roundup Ready

Hybrid

Victory V75-03CL

Mid-slow*

Mid

lmidazolinone

Hybrid

Pioneer®45Y93 (CL)

Mid-slow*

Mid

lmidazolinone

Hybrid

Pioneer®45Y91 (CL)

Mid-slow

Mid

lmidazolinone

Hybrid

InVigor®R5520P

Mid-slow

Mid to mid-late

Roundup Ready

Hybrid

SF Ignite TT

Mid-slow

Mid to mid-late

Triazine

Hybrid

ATR Wahoo

Mid-slow

Mid-late

Triazine

OP

Pioneer®45Y25 (RR)

Mid-slow

Mid

Roundup Ready

Hybrid

Archer

Slow

Mid-late

lmidazolinone

Hybrid

Victory 7001 (CL)

Slow

Mid-late

lmidazolinone

Hybrid

Phoenix CL

Winter

Winter

lmidazolinone

Hybrid

Edimax CL

Winter

Winter

lmidazolinone

Hybrid

Hyola®970CL

Winter

Winter

lmidazolinone

Hybrid

# Phenology response to early sowing. Rankings may vary for later sowing dates. Varieties are ranked from fastest to slowest within phenology groups

* One-year (2019) experiment data only

Lesson 3: Matching varietal phenology with sowing time

Optimal start of flowering in canola

The optimal start of flowering (OSF) for canola has been identified for locations across Australia a subset of which is displayed in Table 2.

Table 2. Optimal start of flowering date for canola growing localities in South Australia

Location

Optimal start of flowering date

Acceptable range (days)*

Soil type

PAWC ** (mm)

Bute

18 July

42

Red sandy clay loam

139

Kadina

18 July

36

Calcic loam

102

Lameroo

19 July

32

Loamy sand

90

Yeelanna

19 July

53

Duplex

152

Minlaton

21 July

43

Red sodosol

88

Loxton

21 July

25

Sand

118

Wudinna

22 July

20

Red sandy clay loam

139

Karoonda

22 July

33

Sandy loam

136

Hart

25 July

37

Clay calcarosol

183

Booleroo

26 July

31

Clay loam

128

Naracoorte

28 July

29

Dark grey clay

80

Spalding

29 July

38

Red chromosol

143

Tarlee

4 August

47

Duplex

225

Bordertown

11 August

34

Grey vertosol

128

* Maximise yield by flowering in the period around the optimum flowering date. For example, at Hart canola should start flowering between 6 July and 12 August (from 19 days before 25 July to 19 days afterwards).

**PAWC = plant available water content (mm) of predominant soil type.

(Source: Lilley et al., 2019; further information at Canola Flowering Calculator - CSIRO ).

The duration and timing of the OSF varies with site and season but not with variety. Sowing date by variety combinations that achieve OSF and maximise yield have been identified.

  • Flowering in the OSF period maximises average yield.
  • Flower too early: the risk of frost stress during early grain fill is high.
  • Flower too late: the risk of heat stress during flowering is high.
  • Flowering too late increases the risk of water stress.
  • Locations differ in the relative importance of frost, heat and water stress.

Lesson 4: Sow slow spring canola late March to mid-April

Slow developing spring canola can be sown from late March to mid-April. Slow spring varieties respond to vernalisation, so they require more thermal time to flower when conditions are warm (for example, from early sowing) than when it is cold (later sowing). Slow spring varieties sown in this window will still flower at the optimum time in SA. There are currently both hybrid and OP varieties available to sow in this window (Table 2). Attention to detail in the fallow period will also increase the likelihood of canola establishing well from a March/early April sowing. Consider the likelihood of having enough moisture for canola to germinate in this period before selecting a slow developing variety. Early sowing of slow spring canola is a useful strategy after a wet summer, where the longer vegetative phase (compared with sowing faster varieties later) gives more time for roots to access subsoil water, resulting in higher biomass and higher grain yield. Sowing a slow spring variety is a useful strategy to avoid frost as they have a very stable flowering window, meaning that they will flower in a relatively tight window in late winter/early spring regardless of sowing date and they also provide grazing options on mixed farms.

Lesson 5: Sow mid-spring canola mid-April to early May

Mid-spring canola has universal adaptability in SA. It can be sown from the second week of April if rainfall allows, and will also perform well when sown later, from the last week of April to early May. These mid-spring varieties often have a subtle vernalisation response (less than slow spring canola). This means that they are slower in warm autumn conditions than fast spring varieties. When sown later (late April to early May), this small vernalisation requirement is quickly met, so mid spring varieties may not be significantly slower than fast spring varieties from later sowing. In an ‘average’ season, mid-spring canola varieties have similar yield across sowing dates (not necessarily the highest at any one date), whereas slow spring varieties are higher yielding from early sowing and fast spring varieties higher yielding from later sowing.

Lesson 6: Sow fast spring canola late April to mid-May

Fast developing spring canola varieties have little to no vernalisation response. These varieties are suitable for sowing in late April to mid-May. When sown earlier, fast spring varieties develop rapidly and can be exposed to frost damage (dry frosty years) and disease (wet years) or produce low biomass. Sowing fast spring varieties early resulted in significant grain yield penalties from disease (2016) and frost (2014 and 2018) across OCP experiments in SA. In contrast, at very high yielding sites (> 4t/ha) fast spring canola sown late often had the highest yield.

Unlike mid-spring canola, there is little flexibility in the sowing window of fast spring canola. Fast spring canola is best suited to systems where sowing is likely to be later in the window, and in low rainfall environments. In seasons where there is a wet summer followed by dry winter, fast spring canola can be penalised as there is not enough time to access water stored deep in the subsoil.

Table 3. Recommended sowing dates for key South Australian locations for three phenology types. Following these sowing guidelines will ensure varieties flower within their ideal OSF window. Table 3. The table shows the recommended sowing dates for key South Australian locations, Lameroo, Hart, Yeelanna, for three phenology types, slow, mid, fast. Following these sowing guidelines will ensure varieties flower within their ideal OSF window.

Lesson 7: Apply post-sowing nutrition as required

Once the crop has established well and growers and agronomists have a better gauge of the season, further N decisions need to be made.

The average seed protein content across all OCP experiments was 22.6%. On average N removal in grain was 36kg N/t. Assuming 50% efficiency, 72kg N/ha was required for each t/ha expected yield.

Protein ranged from 17% (low N, high rainfall sites) to 32% (low rainfall, high N sites), meaning that N removal ranged from 27 to 51kg N per tonne of grain. Seed protein concentration was always negatively correlated with oil concentration, so as protein increased, oil declined. On average, oil and protein comprised 64% of the canola seed. Nitrogen use efficiency was highly variable across trials, but a rule of thumb is to use a figure of 50%, meaning that 50% of the N available to the crop (mineral N at sowing + mineralisation in-crop + fertiliser inputs) will be converted into grain (in an average season). Therefore, growers should budget on 72kg/ha N (through a combination of mineral N at sowing + mineralisation in-crop + fertiliser inputs) per tonne of targeted grain yield.

Despite being one of the most widely researched aspects of grain production, there have been few major advances in N nutrition management over the time canola has been widely cultivated. However, it is known that under intensive cropping the levels of soil organic C, and therefore, the ability of the soil to supply N to crops is in decline. This means that in the future more fertiliser N may need to be supplied or more efficient techniques to achieve crop yield need to be found. Applying N by mid-row banding may be a useful option as a method of using available inputs in a different way and there has been some recent research on mid-row banding N in cereals. Further experiments exploring mid-row banding of N fertiliser for canola nitrogen use efficiency are underway.

Lesson 8: Understand the critical growth period

All grain crops have a ‘critical period’ for yield determination during their growth; when the number of grains, and hence, the yield potential is determined. During the critical period, yield is very sensitive to any kind of stress (for example, water, nutrition, temperature and radiation) and so in any environment it is important to sow and manage crops to minimise the risk of stress and ensure adequate water and nutrients are available to the crop at this time.

The critical period for cereals has been established as the period approximately 20 days before flowering, while for grain legumes it has been identified as the period approximately 20 days after flowering. Surprisingly the critical period for canola had never been identified prior to OCP. Understanding the timing of the critical growth period enables growers to select a sowing date and variety combination which ensures the critical growth period occurs when the growing environment is likely to be the most favourable (balancing risks of water, heat and frost stress). The critical period for canola occurred approximately 350°C days after the start of flowering (Kirkegaard et al., 2018). The crop at this stage has the largest number of very sensitive organs – recently opened flowers, flower buds and small pods. Any significant stress at this time causes the abortion of flowers and pods, and those pods that remain will be smaller and develop fewer and smaller seeds due to the impacts of stress on their developing ovaries during the critical period. Yield was significantly reduced by 40% when stress was applied during this period but was less affected before or after that period (see next section of this paper). Oil% was also reduced by stress during this period.

Managing canola to avoid stress in the critical period

There are two main ways in which growers and consultants can use this information:

1. Careful sowing date and variety selection:

Sowing suitable varieties at the correct time to ensure that flowering commences at the optimum time (optimal start of flowering; OSF) will minimise the exposure of the crop to the combined risks of temperature, water and radiation stress.

2. Managing water and N supply

Managing the crop to ensure there is adequate water and N available during the critical period is important. Rainfall may be uncertain, but agronomic strategies can include:

  • Good fallow weed and stubble management to conserve summer rain and mineralise N. If there is no fallow rain, it may be better to abandon plans of growing canola in low rainfall environments.
  • Sowing canola after grain legumes, hay, pasture or fallow.
  • Ensure sufficient N (soil and fertiliser) for yield potential (70–80kg N/t expected seed yield).
  • Split N fertiliser application or mid/side row banding to ensure N is available at flowering.

Lesson 9: Harvest management

Windrowing canola is a useful tool to even and hasten the crop ripening process, and to reduce shattering losses at harvest. Industry recommendations in the past state that canola should be windrowed when 40–60% of seeds on the main stem have changed colour from green to red or brown or black. However, more research conducted in northern NSW over four seasons as part of OCP showed that branches contributed up to 80% of grain yield. Seed colour change (SCC) on the branches starts later than the main stem, so relying solely on the main stem for windrowing decisions will underestimate seed colour change across the whole plant. Windrowing early will lead to smaller seed at harvest, lower yield and lower oil concentration.

It is now recommended that windrowing is carried out when 60% of seed sampled from the middle third of main stem and branches across the whole plant has changed colour from green to red, brown or black.

There can also be significant decreases in oil concentration as a result of windrowing at early stages of SCC. At Tamworth, there was a 6.3 percentage point reduction in oil concentration (38.9% versus 45.2%) when windrowing at the start of SCC compared with windrowing at approximately 60% SCC (averaged across the plant). Findings from this study highlight the potential for significant yield and quality penalties due to early windrow timings with yield losses of up to 55% and decreases in oil concentration of up to 7.7% (37.5% versus 45.2%). Seed should be sampled from across the whole plant to accurately assess seed colour change. Furthermore, results demonstrated the potential benefit of delaying windrow timings with yields optimised at the upper end of traditional industry guidelines of 60% or greater SCC.

Lesson 10: Evaluate financial performance

Crop yield and cost of production as well as risk must be considered when determining the profitability of a canola crop. There is a trade-off between gross income and the expense and risk of producing that crop. The profit-risk effect of critical decisions for canola management has been explored including cultivar (hybrid versus OP), time of sowing and sowing conditions (dry sown versus sown on establishment opportunity) and N fertiliser inputs across the project area (examples for SA include Yeelanna, Hart, Mallee, Upper EP and Brinkworth).

Matching variety to the sowing date in order to achieve flowering in the optimal window is critical to maximising canola annual gross margin ($/ha). As an example, at Yeelanna, modelling using data from OCP field trials, showed sowing hybrid canola with adequate N between 16 and 30 April produced an average gross margin of $1,010/ha (ranging from $309 to $1,153/ha). If sowing was delayed to between 1 and 15 May, average gross margin was $942/ha ($-39 to $1,161/ha), with losses in low rainfall years.

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. This work is a component of the 'Optimised Canola Profitability' project (CSP00187) a collaboration between NSW DPI, CSIRO and GRDC in partnership with SARDI, CSU, MSF and BCG. Thank-you to the South Australian growers and Hart Field Site group for making their land available for the field trials and to the technical officers of the SARDI New Variety Agronomy group for their assistance in conducting the field trials.

Useful resources

20 Tips for Profitable Canola in South Australia

10 Tips to Early Sown Canola

Canola Flowering Calculator - CSIRO

References

Kirkegaard JA, Lilley JM, Brill RD, Ware AH, Walela CK (2018) The critical period for yield and quality determination in canola (Brassica napus L.) Field Crops Research 222, 180-188.

Lilley JM, Flohr BM, Whish JPM, Farre I, Kirkegaard JA (2019) Defining optimal sowing and flowering periods for canola in Australia. Field Crops Research 235, 118-128.

Contact details

Andrew Ware,
Director, EPAG Research
7 Seaton Ave., Port Lincoln
0427 884 272
andrew@epagresearch.com.au
@Ware_AH

GRDC Project code: CSP00187