Maximising systems benefits from dual-purpose crops – early sowing and grazing strategies

Take home messages

  • Winter and spring cereal and canola varieties can be used for dual-purpose. Early sowing with a suitable maturity type for the site and sowing date will maximise forage and yield potential.
  • Higher profits rely on attention to detail with both crop and livestock management – systems benefits include management flexibility and risk management.
  • Timing of lock-up based on growth stage AND residual biomass is a key decision point - but decisions depend on grain vs livestock prices.
  • The tough 2017 and 2018 years with good livestock prices demonstrated the flexible exit options of early-sown dual-purpose crops – graze-out, hay, silage or graze-grain were all profitable.

Introduction

Dual-purpose crops hold great potential to utilise early-season sowing opportunities to provide extra grazing for livestock and maintain grain yield.  With good management, the period of grazing can increase net crop returns by up to $600/ha and have a range of system benefits including widening sowing windows, reducing crop height, filling critical feed gaps, spelling pastures and providing flexible exit options in dry years.  Over ten years of experiments, simulation studies and collaborative on-farm validation across Australia has demonstrated that a wide range of cereal and canola varieties can be successfully grazed and recover to produce combined livestock and crop gross margins that exceed grain-only crops (Table 1).  Systems experiments and collaborating farmers have increased whole-farm profitability by up to $100 per farm hectare by introducing dual-purpose crops onto a portion of the farm.

Table 1. Typical examples of forage, grain yield and gross margins achieved from well-managed dual-purpose crops by collaborating growers in NSW

Crop type

Grazing achieved
(DSE.days/ha)

Grain yield
(t/ha)

Paddock $GM increase above grain only

Winter wheat

1600 - 2700

4.5 – 6.5

+$600 - $1000

Spring wheat

400 - 800

3.0 - 5.0

+$300 - $500

Winter canola

750 - 2500

2.0 – 4.0

+$600 - $1000

Spring canola

300 - 700

1.5 – 2.5

+$300 - $500

Here we provide brief explanations of how grazed crops are able to recover, some best-bet tips on increasing the success and profitability with dual-purpose crops and give some case studies of what we have achieved experimentally and with collaborating growers.

Early sowing with the right variety is the key

Early-sown, slower-maturing “winter” cereal and canola varieties have the longest vegetative period (i.e. produce leaves before heading/flowering) because they have a requirement to experience prolonged cold temperatures to stimulate flowering.  As a result, they can be sown very early (February/March) and provide the most grazing potential.  For example, each week delay in sowing wheat after early March reduces grazing potential by 200-250 DSE.days/ha and potential grain yield by 0.45 t/ha in central and southern NSW. Winter hybrid canolacan grow even faster than wheat in the autumn, so that similar reductions in potential forage with late sowing occur.

Though different strategies and crop types are better suited to different regions due to the rainfall and season length, a mix of the different approaches shown in Figure 1 can be used on the same farm to take advantage of early sowing opportunities in specific seasons to increase and widen the overall operational and crop grazing window.

Capitalising on early sowing opportunities means being prepared – careful paddock selection (manageable weed burdens), strict summer weed control and careful residue management will maximise surface soil water storage to increase the chances of successful establishment.

Safe grazing and lock-up rules

The ultimate goal for managing dual-purpose crops is to maximise profit from the combined income from the grazed forage and the grain.  This requires an understanding of how grain yield is affected by heavier or delayed grazing. The “safe” grazing period for cereal and canola crops is from the time the crop is well anchored, until the reproductive parts start to elongate above the ground and can be damaged or removed by the livestock (DC30 for cereals and bud elongation for canola).  Any crop can be grazed in this window and grazing will usually delay flowering from a few days to 2 weeks - depending on grazing duration.

Our studies have demonstrated that the time of lock-up and the residual biomass are the critical issues. We can define the overall grazing window into “safe”, “sensitive” and “unsafe” periods related to the impact on grain yield (Figure 1).  The early and “safe” grazing period is once the crop is well anchored and there is still plenty of time for recovery after a period of grazing, even if the crop is grazed quite heavily.  The late and “unsafe” period is when the reproductive parts of the crop (spikes in wheat, or buds in canola) are elongating above the ground, and can be removed by stock, and there is also too little time for the crop to recover enough biomass by anthesis to set a reasonable yield potential. Most growers can easily identify these two periods by testing crop anchorage to start grazing and checking crop development stage to stop grazing.

The “sensitive” period is the period in which the crop has not yet begun to elongate, but where yield recovery can be very sensitive to the amount of residual biomass left. This is the period where some idea of how much residual biomass is needed to reach a specified target grain yield can assist growers with lock-up decisions to avoid yield loss while maximising grazing potential.

This is a graph showing yield recovery (% of un-grazed crop) of grazed dual-purpose crops highlighting the safe, sensitive and unsafe periods of grazing.  Yield recovery from grazing during the sensitive period for a given target yield is affected by the residual biomass at lock-up.  Late grazing reduces the time for recovery, so more residual biomass is needed.

Figure 1. Yield recovery (% of un-grazed crop) of grazed dual-purpose crops highlighting the safe, sensitive and unsafe periods of grazing.  Yield recovery from grazing during the sensitive period for a given target yield is affected by the residual biomass at lock-up.  Late grazing reduces the time for recovery, so more residual biomass is needed.

At our main experimental site near Greenethorpe, we used experiments with different times and intensity of grazing to investigate the relationship between:

Residual biomass (lock-up) <---> Critical biomass (anthesis) <---> Target yield

An example is that a typical grazing Kittyhawk wheat crop sown on 10 April with a target yield of 4.5 t/ha would require a critical anthesis biomass of around 8 to 9 t/ha.  This critical biomass would require at least 0.5 t/ha of residual biomass to be left in late July when the crop becomes unsafe to graze without removing elongating heads (i.e. heads removed if past Z30).  Grazing past this point would require close attention to grazing height to ensure heads were not being removed, and more residual biomass (1.0 -1.5 t/ha) would be needed to be left at lock-up in mid-August to achieve the same critical anthesis biomass, because there is less time left to reach the biomass for the target yield (see Table 2). Note that the spring wheat EGA Gregory sown on 8 May generally had similar critical and residual biomass levels to attain similar yields.

Table 2. Indicative biomass requirements on different lock-up dates to reach different yield targets in wheat. As the target grain yield increases from 3 to 5 t/ha, it is necessary to either lock-up earlier or leave more residual biomass to achieve the critical anthesis biomass required.

Target grain yield (t/ha)

Critical anthesis biomass (t/ha on 1 October)

Residual lock-up biomass required (t/ha) on:

14 July

1 August

14 August

28 August

3.0 t/ha

5.4

<0.2

<0.2

<0.2

1.3

4.0 t/ha

7.2

<0.2

<0.2

1.2

3.5

5.0 t/ha

9.0

0.8

1.8

3.0

5.3

For canola the residual biomass requirement left after grazing is higher than wheat, due to the inherently heavy and thick stem bases and slower regrowth after grazing. Spring canola requires about 1.5 t/ha of residual biomass left when locked up at the end of July (when the stems begin to elongate) to ensure 2.5 to 3.0 t/ha yield potential. Earlier-sown winter canola has even thicker stem bases and requires around 2.5 t/ha of residual biomass for recovery.

Trade-offs and economics

Ultimately economics (feed value vs grain value) in the farm enterprise dictates the acceptable level of grain yield loss (if any) for dual-purpose crops.  In many cases, especially where the feed is being used to fatten or finish lambs or cattle, it is possible that accepting a grain yield penalty makes the most economic sense, as shown for the moderately grazed crop (shaded in Table 3).

Table 3. Amount of grazing achieved and grain yield from different grazing treatments in a EGA Wedgetail crop at Greenethorpe in 2013.  Income was highest with a small grain yield penalty as the extra grazing was more profitable than yield lost.

Lock-up time

Grazing intensity

Sheep grazing
d/ha

Grain yield

Paddock $GM increase above un-grazed

Un-grazed

None

0

4.35

0

DC30 (safe)

Hard

1730

4.36

$653

DC32 (sensitive)

Moderate

2530

3.96

$853

DC32 (sensitive)

Hard

2730

3.28

$758

In a review of 134 different grazing wheat experiments we found <10% returned less than grain only, the median increase in net returns from grazing was 25% and in one third of cases, net returns increased by 75% or more.  In the 87 canola grazing experiments returns were somewhat less (median 17%) due to less grazing, and higher grain-value and so increased economic risks from yield reductions.

A grazing tool to assist decision making at lock-up

Advice on grazing and lock-up management has mostly revolved around crop phenology rules, or calendar dates that come from trial and error over many years.  The significant impacts on yield from the removal of reproductive parts by late-grazing are well known. To maximise grain yield growers are advised to remove stock before DC30 for cereals and bud elongation in canola.

Our work demonstrates that the risk of a yield penalty associated with grazing is likely to increase as the grain yield potential increases, because a 5 t/ha crop requires a higher level of biomass at anthesis than a 3 t/ha crop.  As a result, either an earlier lock-up, or more residual biomass at lock-up is required to reach the higher yield target.  Decisions to continue grazing at the possible expense of grain yield depend on the yield target (Table 2).

Decisions about lock-up times and trade-offs between grazing and grain will be specific to seasonal prices and grazing enterprises.  Our grazing tool allows users to set the yield target and investigate the consequences of different lock-up decisions based on relative prices for grain and livestock.  The tool at present does not deal with situations such as 2017 and 2018 where high livestock prices and probable yield failure meant grazing out was a wise financial decision.

Whole-farm flexibility and risk management

A well-chosen dual-purpose crop should flower in a suitable window – even if not grazed.  This maximises yield potential for the crops whether they are grazed or not and provides peace-of-mind if circumstances change making grazing impossible or unwise.  Likewise, where seasonal conditions deteriorate (as in 2018) and crop recovery after grazing is poor, the crops can be cut for hay, silage or grazed out as sacrifice crops.  In this way, dual-purpose crops provide an excellent risk-management tool on mixed farms with several “exit points” as seasonal conditions and relative prices change.

On a typical 1500ha cropping program, the inclusions of around 500ha of dual-purpose crops might create an extra 2-3 DSE/ha of winter stocking that can be considered as available. Growers can utilise this as feed by increasing the stocking rate, or maintain livestock at the same farm level, but take the opportunity to winter-clean areas of pastures.  Dual-purpose crops can also be introduced onto graze-only farms to assist in rejuvenating areas of perennial pastures, and to generate income to control difficult weeds, with an excellent opportunity to re-establish clean pastures after a period of cropping.

At Greenethorpe in 2018, the value of early-sown grazing crops was demonstrated in a Decile 1 Year (Table 4 – grazed treatment EBIT are shown in bold).  The Manning winter wheat failed to produce grain due to very late flowering under drought but grazing it out (i.e. an extra 3.2 t/ha forage in early summer) proved to be the most profitable option.  The dual-purpose (graze/grain) Kittyhawk wheat and Hyola970 canola both provided much higher profitability than the grain only options and were also more profitable than either of the grain only spring crop options (Coolah wheat or Invigour4510TT) sown in early May (Table 4).

Table 4. Forage and grain production and summary economics of different graze and grain crop options at Greenethorpe in 2018 in a Decile 1 rainfall year.  Estimated at real 2018 costs and prices.

Crop

Sow

Grain Yield (t/ha)

Winter graze (t/ha)

Summer graze (t/ha)

Gross income ($/ha)

Total costs ($/ha)

EBIT ($/ha)

Wheat

Manning (graze out)

3/4

0.0

2.3

3.2

2,058

349

1,709

Kittyhawk (graze/grain)

3/4

1.9

1.5

0.0

1,360

497

862

Kittyhawk (grain only)

3/4

1.6

0.0

0.0

685

561

123

Coolah (grain only)

8/5

2.5

0.0

0.0

1,102

452

650

Canola

Hyola® 970CL (graze/grain)

4/4

0.9

3.5

0.0

1,816

565

1,251

Hyola970CL (grain only)

4/4

1.0

0.0

0.0

527

568

-41

InVigor® 4510TT (grain only)

7/5

1.1

0.0

0.0

609

566

43

Grazing value ($/ha) = Plant DM (kg) removed x Dressed wt. (c/kg) x FCE (0.12)/kg DM x dressing percentage [DM removed x $6.25/kg x 0.12 x 0.5].  All grazing was done by lambs.
Lamb prices=average of light/heavy/trade at correct distribution across NSW for last 3 yrs.=$6.25/kg dressed.
All grain yields are from HI cuts and are at 8% moisture (canola, pulses) or 12% moisture (wheat).
All wheat was at APH2 (>15% protein with < 5% screenings).

The opportunities are significant, but the crop and livestock management requirements to capitalise on dual-purpose crops are considerable.  Successful early establishment, weed control and withholding requirements, stock planning, management and logistics are not trivial to optimise the whole-farm benefits of the extra winter forage.

Managing in and out of early-sown dual-purpose crops

We have mentioned that managing into the DP crop requires good planning and paddock selection, managing weed seed banks down, and choosing situations with good water and N storage (e.g. after cleaned pasture, grain legume or fallow).

Managing out of the crop also requires some consideration.  Long-season, dual-purpose crops can leave profiles extremely dry, especially after dry seasons such as 2017 and 2018.  For example, in 2018 at Greenethorpe, the roots of dual-purpose winter wheat and canola sown on April 1 reached depths of 3.8m and left the subsoils extremely dry.  Depending upon the summer and autumn rainfall, some consideration needs to be given to a wise crop/pasture option in the following season.  For example, following a winter canola with another early-sown DP cereal would only be advisable if substantial rainfall had refilled the profile to reduce the risk of poor forage production in a dry autumn. In contrast, should a wet summer and autumn refill the profile to facilitate a subsequent early-sown winter wheat (an excellent option under those circumstances), then high nitrogen levels are likely to be required (i.e. ensure the crop has at least 150 kg/ha N available at sowing from soil and fertiliser).

A few tips for success with grazing crops

  • First time?  Get good agronomic advice and plan well ahead.
    • What is your livestock plan to make money from the extra winter feed?
  • Select a suitable paddock and be prepared to sow early
    • Weed control, withholding periods, stubble management, stored water for early-sown crops
  • Sow early with the right crop and variety – several options available
    • Winter wheats in March, long-season springs wheats in mid-April, spring wheat late-April
    • Winter canola types in March, spring hybrid types from mid-April
    • Select vigorous canola varieties (hybrids) with good blackleg resistance (>R-MR)
  • Protect early-sown crops from establishment pests and aphids that transmit virus
    • Seed dressings are affordable and effective, but follow-up aphid sprays in warm autumns may be required if aphids persist due to Barley Yellow Dwarf virus.
  • Aim for a good plant population for good early biomass production for grazing
    • 150 plants/m2 for wheat; 40 plants/m2 for canola
  • Ensure sufficient N up-front for good early biomass production
    • 100-150 kg/N for winter wheats and canola; 50-100 kg/ha for spring wheats and canola
  • Don’t graze too early as crops are building root mass and can be checked
    • Twist and pull test – usually need at least 1.5 t/ha biomass (6-8 leaf stage in canola)
    • Recovery and winter growth of canola slower than cereals
    • Graze canola once for longer as animals take some time to adjust (at least 2 weeks grazing)
  • Animal health issues
    • Take usual precautions for bloat and nitrate poisoning as usual for palatable feed
    • Don’t fertilise with N close to grazing, apply upfront and post-grazing
  • *Na/Mg supplements required for grazing wheat to maximise live-weight gain
    • For canola take usual Brassica precautions, cattle are more sensitive than sheep
  • Grazing management
    • Stocking rates around 1000 kg/ha live-weight work well, but adjust to feed on offer
    • Animals take time to adjust to feed and do best if grazed for longer – avoid frequent change
  • Lock-up time is key!!
    • Remove stock before DC30 in wheat and bud elongation in canola
    • If grazing later, ensure grazing does not remove reproductive parts
  • Top-dress N after grazing to assist yield recovery
    • Assume wheat needs to see 40 kg N/ha for every 1 t/ha of yield and canola 80 kg N/ha  - and adjust topdressing according to existing N and target yield.

Further reading

GRDC Factsheet Dual purpose crops

Australian Grain - Match flowering, sowing date for dual-purpose crop success

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 Rod Kershaw, “Iandra”, Greenethorpe for the use of land since 2013, Peter Hamblin and staff at Kalyx (Young) for management of the field experiments at Greenethorpe in 2013 and 2014, and staff at CSIRO Ginninderra Experiment Station for assistance with field experiments in 2017 and 2018.

Contact details

John Kirkegaard
CSIRO Agriculture
GPO Box 1600, Canberra ACT 2601
Ph: 0458 354 630
Email: john.kirkegaard@csiro.au

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