BILOELA GRAINS RESEARCH UPDATE - Home - GRDC · 2018. 12. 6. · Getting crop nutrition right in CQ. Panel session on deep P, K & N. Doug Sands, DAF Qld., Chris Dowling, Back Paddock

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GRAINS RESEARCH UPDATEDRIVING PROFIT THROUGH RESEARCH

CENTRAL QLD EMERALD - DECEMBER 4 BILOELA - DECEMBER 5

10107 GRDC CQ Updates cover 2018.indd 1 9/11/2018 11:57 AM

EMERALD GRDC Grains Research Update

Tuesday 4th December 2018 McIndoe Function Centre

AGENDA Time Topic Speaker(s)

9:00 am Welcome

9:10 am Chaff lining & tramlining problem weeds. Plus: Is glyphosate resistant milk (sow) thistle a concern for CQ?

Paul McIntosh, Pulse Australia/AHRI

9:40 am CQ sorghum agronomy. New research: lodging, row spacing, weeds, time of sowing.

Darren Aisthorpe, DAF Qld. & Trevor Philp, Pacific Seeds

10:25 am PBA Drummond - A new chickpea variety for CQ in 2019! How it performs? Making it perform!

Penny Borger, DAF Qld.

10:35 am MORNING TEA

11:05 am Designing flexible mid-size on-farm grain handling facilities.

Andrew Kotzur, Kotzur Silos

11:40 am What's new in storage? Fumigating large silos. Fumigants & protectants– latest trials.

Philip Burrill, DAF Qld.

12:10 pm CQ farming systems - GM & $ return/mm water. Darren Aisthorpe, DAF Qld.

12:35 pm LUNCH

1:30 pm Helicoverpa resistance – protecting pulse profits. Melina Miles, DAF Qld.

1:55 pm Nitrogen - what's new & how does it apply to CQ? Surface applied urea; how fast does N move in soil; N use efficiency in older crop soils. Implications for how & when you apply N in CQ.

Chris Dowling, Back Paddock Co

2:25 pm Getting crop nutrition right in CQ. Panel session on deep P, K & N.

Doug Sands, DAF Qld., Chris Dowling, Back Paddock Co. plus growers Brian Gregg & Shane Eden

3:05 pm CLOSE

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BILOELA GRDC Grains Research Update

Wednesday 5th December 2018 ANZAC Memorial Club

AGENDA Time Topic Speaker(s)

9:00 am Welcome

9:10 am PBA Drummond - A new chickpea variety for CQ in 2019! How it performs? Making it perform!

Merrill Ryan, DAF Qld.

9:35 am CQ sorghum agronomy. New research: lodging, row spacing, weeds, time of sowing.

Darren Aisthorpe, DAF Qld. & Trevor Philp, Pacific Seeds

10:05 am Chaff lining & tramlining problem weeds. Plus: Is glyphosate resistant milk (sow) thistle a concern for CQ?


10:35 am MORNING TEA

11:05 am Sowthistle - biology, management & glyphosate resistance. How big is the threat in CQ?


11:30 am Designing flexible mid-size on-farm grain handling facilities.

Andrew Kotzur, Kotzur Silos

12:00 pm What's new in storage? Fumigating large silos. Fumigants & protectants– latest trials.

Philip Burrill, DAF Qld.

12:35 pm LUNCH

1:35 pm Helicoverpa resistance – protecting pulse profits. Melina Miles, DAF Qld

2:05 pm Nitrogen - what's new & how does it apply to CQ? Surface applied urea; how fast does N move in soil; N use efficiency in older crop soils. Implications for how & when you apply N in CQ.

Chris Dowling, Back Paddock Co

2:40 pm Getting crop nutrition right in CQ. Panel session on deep P, K & N.

Doug Sands, DAF Qld., Chris Dowling, Back Paddock Co. plus grower Lee Jones

3:15 pm CLOSE

Central Qld GRDC Grains Research Updates 2018

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Contents

PBA Drummond - A high yielding desi chickpea variety for Central Queensland ........................................... 5 Merrill Ryan, Kristy Hobson, William Martin, Penny Borger, Kevin Moore, Col Douglas and Peter Keys

Finding a balance – optimising sorghum agronomy in central queensland and how it has changed over the last 15 years ................................................................................................................................................... 11

Darren Aisthorpe

Farming systems: GM and $ return/mm water for farming systems in CQ ..................................................... 19 Darren Aisthorpe

On-farm grain storage: planning for profit ..................................................................................................... 26 Andrew Kotzur

Grain storage – updates for fumigation in large silos and grain protectants .................................................. 29 Philip Burrill, Greg Daglish and Manoj Nayak

Helicoverpa armigera resistance management in grains ................................................................................ 39 Melina Miles

Chaff lining and chaff tramlining to reduce problem weed populations......................................................... 47 Annie Ruttledge, Paul McIntosh, John Broster, Annie Rayner, Kerry Bell, Michael Walsh, Michael Widderick

Sowthistle biology – management & resistance status .................................................................................. 55 Paul McIntosh

Nitrogen management. A seasonal journey with many routes and destinations .......................................... 64 Chris Dowling

Getting nutrition right in Central Queensland ................................................................................................ 70 Doug Sands, Mike Bell and David Lester

Central Queensland Grower Solutions managing subsoil nutrition – Grower experience, Lee Jones.............. 78 Compiled by: Hayley Eames

Central Queensland Grower Solutions managing subsoil nutrition – Grower experience, James Olsson ....... 81 Compiled by: Hayley Eames

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Compiled by Independent Consultants Australia Network (ICAN) Pty Ltd.

PO Box 718, Hornsby NSW 1630 Ph: (02) 9482 4930, Fx: (02) 9482 4931, E-mail: [email protected]

Follow us on twitter @GRDCNorth or Facebook: http://www.facebook.com/icanrural

DISCLAIMER

This publication has been prepared by the Grains Research and Development Corporation, on the basis of information available at the time of publication without any independent verification. Neither the Corporation and its editors nor any contributor to this publication represent that the contents of this publication are accurate or complete; nor do we accept any omissions in the contents, however they may arise. Readers who act on the information in this publication do so at their risk. The Corporation and contributors may identify products by proprietary or trade names to help readers identify any products of any manufacturer referred to. Other products may perform as well or better than those specifically referred to.

CAUTION: RESEARCH ON UNREGISTERED PESTICIDE USE

Any research with unregistered pesticides or unregistered products reported in this document does not constitute a recommendation for that particular use by the authors, the authors’ organisations or the management committee. All pesticide applications must be in accord with the currently registered label for that particular pesticide, crop, pest, use pattern and region.

Varieties displaying this symbol beside them are protected under the Plant Breeders Rights Act 1994.

® Registered trademark


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PBA Drummond - A high yielding desi chickpea variety for Central Queensland

Merrill Ryan1, Kristy Hobson3, William Martin1, Penny Borger2, Kevin Moore3, Col Douglas1 and Peter Keys2

1 Department of Agriculture and Fisheries (DAF), Warwick, QLD 2 Department of Agriculture and Fisheries (DAF), Emerald, QLD 3 NSW Department of Primary Industries, Tamworth, NSW

Key words

chickpea, Central Queensland, yield, variety, PBA Drummond

GRDC code

DAN00212

Take home message

• Seed available now for 2019 sowing

• Tested across 17 CQ trials from 2013-2017

• PBA Drummond on average across trials out yields all CQ varieties including Kyabra and PBA Pistol

• PBA Drummond has more Ascochyta blight (AB) resistance than Kyabra and PBA Pistol

• PBA Seamer remains the best Ascochyta blight and Phytophthora root rot (PRR) disease resistant variety

• PBA Pistol only other central Queensland specific variety available (2012)

• Compare varietal performance for your locality at nvtonline.com.au

• PBA Variety Management Package (VMP) brochure for PBA Drummond is available online at the GRDC, Pulse Australia and Seednet websites

Background

Pulse Breeding Australia (PBA) is contributing to a more profitable chickpea industry by releasing more stable high yielding varieties, requiring fewer input costs and with acceptable seed quality.

Variety releases are a complete agronomic package with plant height, lodging resistance and seed size a given. Yield advantage and disease resistance coupled with acceptable maturity to bring greater profit and sustainability to the farming system.

Every year in CQ, two trial sites are sown with approximately 350+ breeding lines, one in the Dawson Callide and one in the Central Highlands. An additional two National Variety Trial (NVT) sites with 15 key entries sample additional CQ cropping areas.

PBA Drummond resulted from a cross made in 2006 between PBA HatTrick and PBA Pistol . Both these PBA bred parents were released to industry as varieties in 2012. Seven years later a genetic combination of these two varieties is now available.

A single F3, Ascochyta blight resistant, plant was selected at Tamworth and multiplied at Warwick in 2010. Seed went to Biloela in 2011 for selection and entered CQ yield trials from 2012 onwards.

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Pedigree seed was commenced in 2014 and 300kg delivered to the commercial partner for increase in the 2017 season.

Yield results

Overall CQ yield averages from PBA and NVT trials has shown PBA Drummond to be 7%, 8% and 10% higher yielding than PBA Pistol , Kyabra and PBA Seamer respectively. Data has been obtained from 17 trials (Biloela, Banana, Theodore, Springsure, Emerald, Capella) across 5 diverse seasons from 2013-2017. The spread of seasonal conditions are summarised in Table 1.

Table 1. Range of field conditions at CQ trial sites 2013-2017

Trait Range

Sowing dates 28 April to 2nd June (6 week spread)

Sowing depth Up to 5 inches deep

Row spacing 0.5m – 1m

Flowering 54-78 days (3.5 week spread)

Maturity 108-140 days (4.5 week spread)

Harvest 135-174 days (5.5 week spread)

In crop rainfall 20mm – 400+mm

Mean site yield 1.6t/ha – 3.6t/ha

Tables 2 and 3 represent the yield data by site for PBA Drummond from 2013-2017 for the Dawson Callide (DC) region and the Central Highlands (CH), respectively. In the Dawson Callide, PBA Drummond yielded anywhere from 88-121% of PBA Pistol and in the Central Highlands, from 92-123% of PBA Pistol .

Table 2. Yield of desi chickpea in the Dawson Callide from 2013-2017

Variety Dawson Callide1

Yield as a % of PBA Pistol and in brackets, yield in t/ha

5/6/13* 28/4/14* 18/5/15* 29/4/15* 22/5/16* 29/5/17* 17/5/17*

Nearest town Row spacing (m) Biloela

1.0 Banana

1.0 Jambin

0.72 Banana

1.0 Jambin

0.72 Jambin

0.5 Theodore

0.5

PBA Drummond 107 96 (2.19) 114 (2.37) 88 (2.18) 104 (3.40) 112 (3.52) 104 (2.04) 121 (2.46)

PBA Pistol 100 100 (2.27) 100 (2.08) 100 (2.49) 100 (3.28) 100 (3.13) 100 (1.97) 100 (2.03)

Kyabra 98 89 107 106 98 98 97 104

PBA Seamer 97 91 106 105 93 105 99 115

Moti 101 – 108 106 91 104 101 104

PBA HatTrick 94 80 91 99 88 96 90 97

PBA Boundary 97 87 106 107 89 98 – –

Probability, LSD (t/ha) <0.001,

0.21 <0.001,

0.23 0.0579,

0.28 <0.001,

0.18 <0.001,

0.29 0.0176,

0.22 <0.001,

0.25


7 Source: Trial results from Pulse Breeding Australia (PBA) and National Variety Trial (NVT) programs (www.nvtonline.com.au). * Sowing date 1 Calculated by averaging the year group from the NVT online long-term yield app for 5 Dawson Callide sites 2013–2017

Table 3. Yield of desi chickpea in the Central Highlands from 2013-2017

Yield as a % of PBA Pistol and in brackets, yield in t/ha

Variety Central H’lands1 15/5/13* 1/6/13* 7/5/14* 8/5/14* 15/5/14* 6/5/15* 13/5/16* 25/5/16* 31/5/16* 2/6/17*

Nearest town Row spacing (m) S’sure

1.0 Emerald

1.0 Capella

1.0 S’sure

1.0 Emerald

1.0 Emerald

1.0 S’sure

0.5 Emerald

0.5 Capella

0.5 Emerald

0.5

PBA Drummond 109 104 (2.34)

123 (3.33)

113 (2.21)

107 (2.25)

101 (2.72)

101 (1.82)

114 (3.02) 92 (3.5) 108

(2.19) 100

(3.02)

PBA Pistol 100 100 (2.26)

100 (2.71)

100 (1.96) 100 (2.1) 100

(2.69) 100 (1.8) 100 (2.65)

100 (3.79)

100 (2.03)

100 (3.03)

Kyabra 100 96 110 106 110 100 94 95 97 96 96

PBA Seamer 97 97 105 99 105 101 99 94 99 95 98

Moti 101 98 – 108 110 103 101 100 97 100 92

PBA HatTrick 94 84 100 94 93 86 90 90 92 94 80

PBA Boundary 98 – 97 98 95 89 97 92 – – –

Probability, LSD (t/ha) 0.0517,

0.22 <0.001,

0.24 <0.001,

0.21 0.0013,

0.21 <0.001,

0.43 <0.001,

0.16 <0.001,

0.28 <0.001,

0.19 <0.001,

0.24 <0.001,

0.28

Source: Trial results from Pulse Breeding Australia (PBA) and National Variety Trial (NVT) programs (www.nvtonline.com.au). * Sowing date 1 Calculated by averaging the year group from the NVT online long-term yield app for 11 Central Highlands sites 2013–2017

Disease results

In Table 4, data is given for Ascochyta blight (AB) and Phytophthora root rot (PRR) from yield loss trials conducted over 3 years from 2015-2017 at Tamworth and Warwick, respectively. The Ascochyta northern rating of PBA Drummond (Susceptible -S) indicates that it has better resistance than Kyabra and PBA Pistol (both Very Susceptible-VS) but not as good as PBA HatTrick (Moderately Susceptible-MS) or the best available resistance level in PBA Seamer (Moderately Resistant-MR).

In most CQ seasons, there will be no cost benefit of applying a fungicide before Ascochyta is detected. When conditions do favour Ascochyta, a reactive foliar fungicide program and protective pod sprays are warranted. Monitor the crop 10-14 days after each rain event.

PBA Drummond is rated Susceptible (S) to Botrytis grey mould (BGM) and so managing row spacing and sowing time can assist with risk levels. A registered fungicide seed dressing is highly recommended for early control of seedling root rots, seed transmitted Ascochyta and Botrytis seedling disease. Monitor for Botrytis grey mould in spring as temperatures and humidity rise. Apply a current registered fungicide once Botrytis grey mould has been identified within the crop and before full canopy closure.

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Table 4. Disease ratings and yield loss trial data for CQ grown desi chickpea varieties Variety1 Ascochyta blight (AB)2 Phytophthora root rot (PRR)5

AB

Resistance rating3

Yield t/ha4 % Yield loss PRR

Resistance rating

Yield t/ha4

% Yield loss

2015 2016 2017 2015 2016 2017 2015 2015

PBA Drummond S 0 0 0.88 100 100 53 S 0.15 95

PBA Pistol VS not tested S not tested

Kyabra VS 0 0 0.21 100 100 89 MS not tested

PBA Seamer MR 1.47 1.92 1.68 24 45 7 MR 0.37 87

PBA HatTrick MS 0.24 0.08 1.58 87 98 6 MR 0.81 68

PBA Boundary MS 0.91 1.31 1.53 53 70 12 S 0.17 94 Source: NSW DPI and DAF Pulse pathology and PBA breeding teams 1 PBA PistolA and MotiA are rated VS with similar AB yield loss as KyabraA 2 Ascochyta blight yield loss trial, Tamworth 2015, 2016 and 2017, NSW DPI 3 Northern Region AB Rating Scale

4 Yields are in the presence of high disease with no fungicide applications

5 Phytophthora root rot yield loss trial, Warwick 2015, NSW DPI and DAF

Agronomic results

Table 5 presents agronomic data across all 17 CQ trials 2013-2017; note that PBA Drummond flowers a few days later than PBA Pistol , Kyabra and PBA Seamer , but matures at approximately the same time as Kyabra and PBA Seamer .

Plant type, plant height, lowest pod height and lodging resistance are all similar to known CQ varieties. At Warwick in 2016, frost data indicated that PBA Drummond had less plant damage when compared to other varieties, a notable improvement particularly over the more susceptible parent PBA Pistol .


9 Table 5. Agronomic traits for CQ grown desi chickpea varieties

Variety Flowering (Flowering

score1)

Maturity (Maturity

score1)

Plant height (cm)

(Erectness)

Lowest pod height (cm)

Lodging resistance

(Lodging score2) Frost score3

PBA Drummond

Mid (6.7) Early-Mid (4.7) 67.4 (E) 34.5 Good (3.3) 3.2

PBA Pistol Early (3.5) Early (3.5) 75.7 (E) 35.7 Good (3.5) 7.6

Kyabra Early-Mid (5.0) Early-Mid (4.6) 66.4 (E) 35.2 Good (4.2) 4.2

PBA Seamer Early-Mid (5.7) Early-Mid (4.6) 65.4 (Semi-E) 34.2 Good (3.2) 3.5

Moti Early-Mid (–) Early-Mid (3.9) 67.2 (E) 36.2 Good (3.0) –

PBA HatTrick Mid (6.1) Mid (5.4) 63.2 (E) 34.1 Moderate (5.2) –

PBA Boundary Mid (6.7) Mid (5.2) 68.4 (E) 37.2 Moderate (4.6) –

Source: Pulse Breeding Australia 2013–2017 1 Flower & Maturity score: 1 = very early, 9 = very late 2 Lodging score: 1 = fully erect, 9 = flat on ground 3 Frost score (post flowering): 1=low damage, 9=high damage. Frost data collected from Warwick, SQld 2016 (DAQ00193)

Seed quality results

Table 6 gives the seed quality parameters that allow PBA Drummond entry into the bulk export market. Seed size is acceptable, closer to PBA Seamer in size than Kyabra and PBA Pistol . Seed marking percentages fell well within the acceptable range.

Table 6. Seed quality parameters for PBA Drummond relative to current varieties

Variety Seed weight

(g/100 seeds) Tiger/blotch marking (%)

Milling performance (%)

PBA Drummond 21.7 1.6 51.0

PBA Pistol 23.5 5.7 50.7

Kyabra 22.8 1.7 50.1

PBA Seamer 21.5 1.1 48.6

Moti 23.7 0.8 –

PBA HatTrick 20.7 3.6 43.8

PBA Boundary 20.1 1.3 –

Source: Pulse Breeding Australia. 100 Seed Weight (unsized) averaged over 15 CQ trials from 2013–2016 Seed Markings, count in 300 seeds as a %, 14 CQ trials 2013-2016 (courtesy of DAN00196) Milling Performance % = Split Yield %, average of 2 CQ sites x 2 years (2013 and 2016)

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Future

It is anticipated that PBA Drummond will replace Kyabra , PBA Pistol and PBA HatTrick which will account for approximately 90% of the CQ area sown.

Varieties to be released in the future are expected to have:

• Yield equal to or greater than PBA Drummond

• Ascochyta blight resistance rating at a minimum of MS

• Large seed size similar to PBA Pistol and Kyabra

• Maintain the agronomic features of PBA Drummond

PBA Drummond is protected under Plant Breeder’s Rights (PBR) legislation. Growers can only retain seed from their production of PBA Drummond for their own use.

An end point royalty (EPR) of $4.95 per tonne (GST inclusive), which includes breeder royalties, applies upon delivery of this variety. Seed is available from the commercial partner Seednet.

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 author would like to thank them for their continued support.

Local growers who partnered with PBA to provide on farm trials include the Johnstone’s from Banana, the Conway’s from Theodore and Peter Lablack from Capella. Support from the Qld DAF NVT team is also acknowledged with their data contributing to the yield analyses.

Contact details

Dr Merrill Ryan Department of Agriculture and Fisheries Hermitage Research Facility, Yangan Road Warwick QLD 4370 Ph: 07 4542 6710 Email: [email protected]

Varieties displaying this symbol are protected under the Plant Breeders Right Act 1994

mailto:[email protected]


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Finding a balance – optimising sorghum agronomy in Central Queensland and how it has changed over the last 15 years

Darren Aisthorpe, DAF Qld.

Key words

sorghum, plant population, row configuration, wide rows, single skip, double skip, yield, grain quality, Central Queensland, yield potential, high yielding, tillers

GRDC code

Farming systems research DAQ382, DAQ00049 - Phases 1 & 2 of the Central QLD Sustainable farming systems project (GRDC and QLD DPI) UQ000075 Tactical agronomy for sorghum and maize

Take home message

• Many of the agronomy packages for CQ were based on MR-Buster or older Pioneer varieties and have served growers well for many years

• Higher yielding hybrids are now available with new attributes and characteristics, however, many have not had agronomic packages developed to the same level as MR-Buster which has caused quality and management issues

• Yield optimisation is a continuous challenge of trying to find an agronomic balance between raw yield and grain quality using the agronomic tools and environment we operate within.

Sorghum has always been considered a key crop in Central Queensland (CQ) and for good reason. The region has a tendency towards a summer predominant rainfall pattern, highly suitable soils and ideal climate for sorghum. However, in the late 1990s/early 2000s it had become apparent to range of growers, consultants and researchers that the industry could be doing significantly better with respect to agronomic management of the crop.

At the time, the Queensland Department of Primary Industries (QDPI) and the Grains Research and Development Corporation (GRDC) had recently funded (1997) phase 1 of a development and extension project – the Central Queensland Sustainable Farming Systems (CQSFS) project. Sorghum agronomy was quickly identified as a key area of R&D for the group to focus on. This is how a technical report from the project released in November 2002 described the state of play prior to the research commencing:

“Sorghum has the potential to perform better in Central Queensland (CQ) than it currently does. Yield losses from poor stands, weeds, inadequate nutrition, variable and unpredictable rainfall, high temperatures and evaporation, and rain at harvest all combine to increase the riskiness of the crop and reduce overall profitability. The use of wide row and skip row configurations in sorghum has been suggested as a means of metering out water to the growing plant such that there will be some water left between the rows at the end of the season to set grain. Therefore, wide rows and skip row configurations are about maximizing yield in dry finishes rather than maximizing plant growth, which is important in CQ where dry finishes are common.” (Wide row and skip row configurations in sorghum in Central Queensland - 2001/02 Technical Report (Reid, et al. November 2002))

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Over eight years and two phases of the CQSFS project, wide ranging research was conducted into sorghum agronomy within the CQ farming environment. The project partnered with local consultants, seed companies and many grower co-operators right across CQ. Trials were conducted into a range of areas relevant to sorghum agronomy including row spacing and population, weed management and crop nutrition.

The findings

The first technical report, quoted above, was released in 2002 at the end of the first phase of the CQSFS project. It reported on trials conducted over a particularly low rainfall period, so had a strong emphasis on crop security rather the top end yield, and the recommendations reflect this. A second technical report was released, detailing the work conducted from late 2002 to 2004. It sought to answer again specifically on row configurations and plant populations, however this time hoping to fill in the gaps around the effect of wide rows and population in higher yielding scenarios.

By the end of 2004, the project released the second technical report with the following recommendations:

“The effect of configuration on yield appears independent of plant population for both low- and high yielding situations indicating that plant population does not compensate for any yield loss incurred with wide rows. For yield potentials around 4 t/ha, the benefits of wide rows were variable while benefits were again evident in some lower-yielding situations. Tillering was also reduced with wide row configurations. In high-yielding situations, established plant populations should be around 50,000 plants/ha while in low- to moderate-yielding situations populations should be 40 – 45,000 plants/ha. Populations below these may incur greater tillering, which could increase management difficulties in the crop. Grain quality was not adversely affected by wide rows. This would be expected if wide rows reduce moisture stress and help plants to remain healthier during the grain filling period. Further, there was no evidence that plant lodging was affected by row width. As a guide for row configuration and plant population decisions:

• If yield prospects are low (say < 3 t/ha) Aim for around 40,000 plants/ha in wide rows. While a low population/wide row strategy may provide sound yields in tough seasons, a penalty may be expected if the season turns out favourably.

• If yield prospects are intermediate (say 3 – 4 t/ha) A best-bet low-risk strategy would be to aim for a moderate plant population (40 – 45,000 plants/ha in wide rows.)

• If yield prospects are high (say > 4 t/ha) Aim for around 50,000 plants/ha with a standard row width.”

(Effect of row configurations and plant populations on sorghum production in central Queensland - 2003/04 Technical Report (Reid, et al. 2004)

Weeds

As row spacing increased, crop competition decreased, which allowed significantly more opportunities for weeds to establish and affect yield potential. Vikki Osten and her weeds team in CQ conducted a range of research trials looking at the effect of wide row sorghum on weed management and the possible yield penalties. Table 1 illustrates what type of yield penalties were identified.


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Table 1. Identified yield penalties due to weeds for different row configurations of sorghum

Row Spacing Weed free yield (t/ha)

Weedy yield (t/ha)

Yield penalty due to weeds

(%)

Weed biomass

(g/m2)

Weed seed production

(no./ m2)

2003 trial 1m solid 4.6 1.9 58 230 N/A 1m single skip 3.8 1.6 57 241 N/A 1m double skip 2.9 1.8 39 174 N/A

2004 trial 1m solid 3.0 2.0 33 268 11788 1m single skip 2.6 1.9 29 259 7526 1m double skip 2.7 2.2 19 302 37462

2005 trial 1m solid 3.2 0.6 81 172 2843 1m single skip 2.7 1.2 56 323 13353 1m double skip 2.1 0.5 76 484 20999

Source: V. Osten, DPI&F Emerald

It is important to note that while feathertop Rhodes grass was present and causing issues within some areas at this time, it was not yet the region-wide issue it was set to become. Despite this, the table clearly illustrates the effect poorly managed weeds within a crop can have, and how much quicker a wide row spacing system can increase weed seed under these systems.

Work was also being conducted on ground cover effects of different row spacing configurations. Again, it was apparent that there was a trade-off between crop security, ground cover and ultimately fallow water storage. The two graphs in Figure 1 show that as row spacing widened, both ground cover post-harvest and ultimately water stored in the fallow were reduced.

Figure 1. Graphs taken from ‘More grain from your rain’ or ‘more crop for your drop’: managing

rainfall in Central Queensland dryland cropping systems (Routley et al. 2006) showing the effect of rowspacing on residual ground cover and fallow water storage.

At the end of the second phase of the CQSFS in 2007, an extensive evaluation of the project benefits to farming systems in CQ was made. To provide a snapshot of how things had changed, I have pulled the following caption from pg. 56 of that report:

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“Row spacing and plant population Substantial research undertaken by the project helped quantify the effect of wide row configurations on yield of wheat and sorghum. This research has shown that wide row configurations (>1m) are an effective risk management tool in sorghum production and that minimal yield losses are experienced with wheat row spacings of up to 50cm in most conditions. The wheat and sorghum row spacings used in Central Queensland have both increased considerably over the last five years as producers have become aware of the benefits of wider row systems. There has been a decrease in the average target sorghum plant population used by producers from 45 300 plant/ha to 35 500 plants per ha over the last five years. This change has been supported by project research that has demonstrated that these lower populations are adequate to achieve optimum yield in most seasons and have some benefits in terms of yield stability in dry seasons. It was pleasing to note a large increase in the number of producers who are prepared to vary plant populations and row configuration in response to seasonal conditions or yield targets, particularly for sorghum. This flexible approach will allow producers to optimise production in an extremely variable climatic environment.” CQSFS 2 (2002 – 2007) An evaluation of project achievements, benefits and outcomes.

10 years on… what’s changed?

Post CQSFS 2 finishing, focus has moved away from direct sorghum agronomy onto other more pressing issues. Growers’ adoption of the wide row spacing systems was extensive and that significantly improved the reliability of the crop in the region and the quality of the grain being produced.

However, feathertop Rhodes grass continued to become more of an issue, particularly in wide row sorghum. Newer chickpea varieties were released which were better suited to CQ and the growth in farm price of chickpea saw growers move away from sorghum as the key crop that it once was, particularly in southern and eastern parts of the CQ region. Seed companies were also releasing newer sorghum hybrid varieties with traits such as stay green, which didn’t seem to follow the agronomy rules around spray out and desiccation of the older varieties, causing issues with harvest and grain quality.

In 2014, GRDC funded a new northern region project with QAAFI, ‘UQ 000075 Increasing sorghum yield with tactical agronomy’ to address the gaps in knowledge, particularly around maximising yield with newer hybrid types and evaluate if the ‘agronomy rules’ needed to be updated. The project again looked at a range of agronomic configurations, including population x hybrid in various environments and row spacing configurations from CQ down to NNSW. One of the key observations from that project was that there was still much to do with respect to optimising yield for a given amount of plant available water. Figure 2(a) shows average mean yield for each trial treatment achieved at all the trials completed across Queensland and NSW compared to expected or predicted yield of MR-Buster (environmental yield) for the conditions. Figure 2(b) shows yield achieved for the plant available water for each of the trial sites. As can be seen by the yield variations for any one level of PAW, optimising planting configurations to suit a given hybrid and the conditions it is being planted into can result in significant benefits.


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Figure 2. Treatment mean yield versus environment yield i.e. mean of site yield from all the

treatments (a), and (b) relationship between treatment means and available water estimated as soil moisture at sowing (0-1.2m) plus in crop rainfall and added irrigation (if any). Results under

preparation for publication. (Rodriguez et al. 2017)

Yields ain’t yields

While maximising yield for the water available to the plant is generally always the goal of growers, achieving this at the cost of high screenings and resulting price penalties or screening costs to make the product marketable is not. As part of the tactical agronomy project in CQ, in 2017 four hybrids were grown on both skip row and solid 1m row spacing configurations.

The trial was planted at three different target population densities on two row spacing configurations.

Figure 3. Yields achieved and yield response curves for the four hybrids used in CQ in 2017 showing significant yield difference between configurations. There was a significant quadratic plant density

effect. I.e. A common curve was fit to each combination of hybrid and configuration with each curve

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having a different intercept value. A common optimum plant density was determined to be at 6.04 plants/m2 (P<0.05) There was a significant difference between the hybrids. Solid configuration had a

significantly higher yield than the single skip configuration.

PAW at planting (14/02/2017) was 195mm with an additional 222mm in crop, 143 kg of N was available at planting, with an additional 138 kg applied post emergence. The aim was to provide a non-limiting supply of N & P and a full profile of moisture at planting, but then treat the trial as a dryland crop after planting. Most of the 222mm had fallen by the end of March, setting the crop up for a big yield potential, however, there was no additional rain during flowering or grain fill to finish the crop.

Figure 3 shows the yield response curve and actual yields for both the skip row and solid row spacing configurations. After statistical analysis, the yield response curves were added and clearly show that the narrow row, high population configuration maximised yields for the trial conditions for all hybrids. Figure 4 then shows on average for both row configurations, how the four hybrids were developing the yield, for the three population levels. Typically for all four hybrids in the trial, as population increases, tiller contribution to total yield declines - an observation which is very consistent even in the CQSFS data.

Figure 4. Main stem and tiller contribution to total yield and average screenings across population

treatments. There was a significant difference between hybrids for average screenings across treatments (P=0.03), however, there was not a significant difference when hybrid x population

density was considered. However, when grain size is considered, we observed average screenings for two of the hybrids starting to spike above 5%, and individual plot results in excess of 10% for some of the solid row spacing, higher population treatments (Figure 5). This raises some interesting observations:

• Tillers typically have a higher level of screenings than the main stem • Significantly lower tiller numbers per plant in high population treatments compared to low

population treatments


17 • We have repeatedly observed (data not shown) that for a given population, we will typically

see more tillering on narrow row configurations than wider row configurations due to higher in-row density in the wide rows.

Figure 5. Average screenings per treatment from both the main stem and tiller stems. For main stem, LSD between treatments was 0.67 of 1% (P=0.05). For tiller stems there was a difference

(P=0.055) between population densities across all hybrids, however there was no significant difference in varieties x population x configuration treatments.

Conclusion

In this nutritionally unlimited trial scenario, the best yields came from high population, narrow row configurations, despite the dry finish. Post-harvest water and N were assessed and there was still 140 mm of PAW available down to 150 cm (though over half of that was sitting below 1 m), yet total screenings (Figure 4) between varieties were significantly different, and tiller screenings were approaching a significant difference (P=0.08) between population densities.

Consistent with the work by the CQSFS team, even in this high yielding scenario, the wider row configurations for all varieties provided good yields with low screenings across the population range and were an obvious safe option even at the higher populations. However, that safety came at a cost of up to 1 t/ha for any given population planted.

When the system was pushed in to the narrower configurations and higher populations than those recommended by the CQSFS work, we were able to achieve a significant yield boost from all varieties. However, we paid the penalty with a spike in screenings, particularly in the hybrids with greater stay-green attributes. This raises the question, the top end yield of all four hybrids wasn’t that different; were the agronomic practices applied to all not ideal for the stay-green varieties? Do some stay-green or newer hybrids need different management strategies? Is this consistent across other commercial stay-green lines? Interestingly, it is usually the high row density or high population treatments which ripen quicker than the low-density treatments, so if you were going to have issues related to premature spray out, you would have expected higher screenings in the tillers of the low-density treatments.

Precision ag brings with it the potential to spatially place any seed anywhere we want it in the field and any distance away from any other seed. This could be a game changer for many, particularly if we are able find a commercially competitive uniculm or non-tillering sorghum variety to pair with that technology. These innovations, along with herbicide tolerant hybrids, have the potential to rewrite the agronomy book when it comes to sorghum management.

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Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers and consultants through both trial cooperation and the support of the GRDC, the author would like to thank them for their continued support.

References

Queensland grains research 2017-18, Regional agronomy, compiled by Jayne Gentry and Tonia Grundy on behalf of the Regional Agronomy Team, Crop and Food Science, Department of Agriculture and Fisheries QLD and GRDC

Summary of recent results from Tactical agronomy for maize and sorghum in the northern grains region, Daniel Rodriguez, QAAFI 2017

Increasing sorghum yield with tactical agronomy, Simon Clarke, Joseph Eyre, Loretta Serafin and Daniel Rodriguez, QAAFI & NSWDPI 2018

‘More grain from your rain’ or ‘more crop for your drop’: managing rainfall in central Queensland dryland cropping systems, Richard Routley, Principal Agronomist, QDPI&F, 2007

Wide row and skip row configurations in sorghum in central Queensland - 2001/02, Technical report – November 2002, Reid, DA, Agius, PB, Bell, MB, Buck, SB, Collins, RB, Conway, MC, Doughton, JC, Farquharson, AD, Kuskie, JC, McCoskerC, K, Osten, VC, and Spackman, GE. QLD Department of Primary Industries and Fisheries & GRDC

Effect of row configurations and plant populations on sorghum production in central Queensland - 2003/04, Technical report – December 2004, Reid, DA, Agius, PB, Buck, SB, Collins, RB, Conway, MC, Kuskie, JC, Spackman, GD, and Sullivan, AC. QLD Department of Primary Industries and Fisheries & GRDC

Project update, newsletter for the CQ Sustainable Farming Systems Project, Issues 17, 19, 20 & 24, December 2002 through to September 2004, written, compiled and edited by CQSFS staff during that period.

Contact details

Darren Aisthorpe Department of Agriculture and Fisheries 99 Hospital Rd Emerald QLD 4720 Ph: 07 4991 0808 Email: [email protected]


19 Farming systems: GM and $ return/mm water for farming systems in CQ

Darren Aisthorpe, DAF Qld.

Key words

Emerald, farming systems, rotations, WUE, $/mm, NUE, N balance, P balance, sorghum, wheat, mungbean, chickpea

GRDC code

DAQ00192 Farming Systems Initiative

Take home message

• Legume rotations don’t equate to free N or any other nutrient

• Most profitable crop sequence has been chickpea/cereal rotation, but at what cost?

• Manure application provide unexpected boosts and is turning up some unexpected benefits.

Background

The project developed six locally relevant farming systems in 2015. These were consistent with those being studied by the Northern Farming Systems Initiative core site near Pampas in Southern Queensland. A range of agronomic practices (i.e. row spacing, plant population), crop types and rotations, crop frequency, planting time/windows, tillage practices, fertiliser rates and planting moisture triggers were adopted and strategically used to develop the following six farming system treatments:

1. Baseline - A conservative zero tillage system that is commonly used. It has approximately 1 crop/year, with fertiliser applied to match 50th percentile yield expectation for the Plant Available Water (PAW) at planting. Crops include: wheat, chickpea and sorghum

2. Higher crop intensity - This system is focused on increasing the cropping intensity to 1.5 crops/year to see whether a higher cropping intensity is more profitable in the long-term. Is a higher risk strategy that plants into lower plant available water, more sustainable from both from an agronomic and economic point of view? Crops include wheat, chickpea, sorghum, mungbean and forage crops/legumes

3. Higher legume - The frequency of pulses is increased in this system (i.e. 1 pulse every 2 years) to assess the impact of more legumes on profitability, soil fertility, disease and weeds. Crops include wheat, chickpea (but not chickpea on chickpea), sorghum, mungbean and new legume crops

4. Higher nutrient supply - This system applies fertilisers to supply adequate nutrition to support 90% of the potential yield based on soil moisture (PAW) at planting. What is the economic implication of increased nitrogen and phosphorus rates that target higher yields and protein level in an environment of variable climate? The crops and other practices are the same as the Baseline system

5. Higher soil fertility - This system is a repeat of the ‘Higher nutrient supply’ system, but with the addition of 20 t/ha of manure in the first year and 40 t/ha in 2016. The system is designed to see if higher initial soil fertility can be maintained with greater nutrient inputs (targeting 90% of yield potential based on PAW). The crops and other practices are the same as the Baseline system

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6. Integrated weed management - This minimum tillage system is focused on 1 crop/year but employs a wide range of practices to reduce the reliance on traditional knockdown herbicides in CQ farming systems. Practices include tillage with full disturbance planting; contact and residual herbicides; and other cultural practices such as high plant population, narrow rows, crop choice and use of emerging technologies. Crops include wheat, chickpea, sorghum and mungbean.

Table 1. Crop rotations at the Emerald site 2015 - 2018

What was done

While there are six clear treatments being managed at the Emerald farming systems site, due to similar planting protocols and sowing trigger points, as can be seen in Table 1, effectively we have had only three different crop rotations over the past four years. The first, and most predominant to date has been the “Baseline” rotation. Four treatments; Baseline, High Nutrient, High Fertility and Integrated Weed Management (IWM) have all followed this rotation to date, however differences in nutrition applied, manure application, row spacing and populations have meant that they are all differentiated from each other. Figure 1 shows what crops have been grown and rainfall received (both in crop and fallow) during the trials progression.

Figure 1. Cropping cycle and accumulated rainfall during both fallow and in crop cycles for the

“Baseline” rotation. Data labels indicate total accumulated rainfall for any given fallow or cropping phase.


21 All four treatments target one crop per year. Fortunately, despite some limited rainfall periods over the past four years, we have been able to achieve this. When you view this graph, what becomes apparent, excepting 2016, is just how little in crop rain was received during winter crop cycles. These crops were almost completely reliant on sub soil moisture to achieve yield, which is the reality of farming conditions in CQ.

Figure 2. Cropping cycle and accumulated rainfall during both fallow and in crop cycles for the “High

Crop Intensity” rotation. Data labels indicate total accumulated rainfall for any given fallow or cropping phase.

Despite the name, the high crop intensity treatment (Figure 2) has only managed to grow one extra crop above to the other treatments in the trial. This was a mungbean crop planted in late February of 2016 on the back of excellent moisture and good planting conditions. However, the tap really turned off during the growing period and temperatures spiked resulting in an average yield of about 1 t/ha, well below expectations given the water available. Fortunately, the crop used little of the soil water profile and with top up rain in late May and early June, the plots were planted to wheat. No other double cropping opportunity has presented during the defined planting window and triggers since.

Figure 3. Cropping cycle and accumulated rainfall during both fallow and in crop cycles for the “High

Legume” rotation. Data labels indicate total accumulated rainfall for any given fallow or cropping phase.

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The “High Legume” rotation is the third rotation which has taken place on site. Again, only targeting one crop per year, but this time with an aim of planting one legume crop in two. It should be noted that the fallow rainfall accumulation over summer of 15/16 and summer 16/17 was higher than the “Baseline” rotation. This was because in winter 2016 the chickpea in Baseline was deep planted before the season “broke” in early June. Then in winter 2017, we planted the wheat as early as we could in April to use available water before it got too deep, but held off sowing chickpeas until late May, as we knew we could chase soil water with chickpea if required.

Results

The treatment differences have been assessed on a range of indices, and typically on a cumulative basis, rather than simply a crop by crop basis. After 4 years of data collection, despite treatments having a superficially similar sequence, the true differences are starting to become apparent.

The interesting responses are in the “High Fertility” and “IWM” treatments. Both possibly the most “radical” treatments of the six. One has had approximately 60 t/ha of feedlot manure applied, and the other, while designed to focus in on weed management, has actually been a very interesting comparison of row spacing and population effect on a farming system.

Figure 4. Total dry matter and grain yield accumulation over the duration of the trial to date

(to Nov 2018) across the six treatments.

Biomass/grain accumulation

Accumulated biomass and grain yields are continuing to diverge as the trial progresses. Note that while the IWM treatment has (understandably) produced the most dry matter of all the treatments, and had produced a yield outcome that is higher than Baseline and High Intensity and comparable to the High Legume and High Nutrient Supply treatments, but lower than the High Soil Fertility treatment.

System Water Use Efficiency (kg/mm)

The Water Use Efficiency (WUE) is a fundamental assessment for any farming system. The goal of any farming operation is to convert water to saleable biomass/grain as efficiently as possible. Figure 5 shows the kg return per mm received for both total dry matter produced, and grain produced over the four years of the trial to date. The calculation used to achieve the kg/mm numbers below are simply total biomass (or grain produced) per ha divided by the difference in starting water (2015) and harvest waters in 2018 + total rainfall over that period of time.


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Figure 5. Trial duration Water Use Efficiency (WUE) in kg/mm of dry matter production and grain

production for the six treatments

From the outset, it appears that the legume rotation has been the most efficient of the treatments for grain produced per mm received. The IWM and High Soil Fertility treatments were the most efficient treatments in converting rainfall to dry matter. High Soil Fertility was almost able to match High Legume for grain produced per mm. Interestingly, despite IWM being more efficient at converting water to biomass, the High Nutrient Supply treatments was close to matching the IWM treatment with respect to grain production.

System WUE ($/mm)

The next logical step, is to calculate what financial return, treatments generate per mm of rain received. The calculation is (grain yields x price) divided by ((difference in starting and finishing waters) + rainfall received during the trial duration). For the gross margin calculation, production costs are subtracted from the grain yields x price calculation.

Figure 6. System Water Use Efficiency ($/mm) and system gross margin water use efficiency ($/mm)

for grain produced across the six treatments over the past four years. Grain values used for gross margin analysis are 10 year median prices at port, minus transport costs ($40/t). These were $221/t

for sorghum, $269/t for wheat, $504/t for chickpea.

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The High Legume treatment to date has clearly come out in front of all other treatments by a reasonable margin. The double bonus of higher price and similar yields to traditional cereal crops has helped the rotations come out on top to date. Conversely, the High Intensity treatment has fallen well behind even the baseline treatment, despite growing an extra crop.

Nutrition

Throughout the life of the trial, use of key nutrients are monitored. The two graphs below in Figure 7 illustrate how the current balance sits based on N and P applied (calculated before planting, based on PAW and the yield target for the treatment (50th percentile or 90th percentile) depending on the treatment). The key standout from these two snapshots is firstly, how heavily we are mining our nutrient resources, even in the high nutrient and fertility treatments, the second is the effect on available N the legume treatments are having on our N balance.

When N removal by grain alone is considered. The trial average across all treatments currently, for every 1 tonne of chickpea harvested, we are also carting away 33 kg of N. So in a typical crop of chickpea (2.2 tonne/ha) you are carting away 72 kg of N per ha. N fixation from nodulation can range between, 20 – 50 kg/N depending on crop size/biomass, so therefore you are running at a net loss, if no additional N is being applied in the system.

However it is still very important to remember that chickpea and legumes generally do provide many other rotational benefits to a farming system. The question is around the long term N balance in the soil. When we compare starting N with finishing N four years later, we are currently sitting at a deficit of about 40 kg of N per ha in the High Legume treatment, with only the IWM treatment sitting lower with a deficit of 52 kg/ha.

Figure 7. Nitrogen and phosphorous (kg/ha) balance over the duration of the trial to date, based on

nutrients applied and then removed with grain harvest.

Conclusion

The trial in CQ has highlighted some important elements of grain production in this region and provides some interesting insights into the importance of every mm of rainfall conserved and how much that extra mm is worth to the bottom line of a grain production business. As the graphs in Figure 7 highlight, even with what some may consider a high fertiliser application program, with a legume rotation included, we are still taking more from our soils than we are putting back.

The high legume rotation challenges many peoples’ perception of the benefits from a heavy chickpea or mungbean based rotation. It certainly has had the best return per ha both in terms of water use efficacy for grain produced but also bottom-line returns. However, given the significant


25 draw down on N and P, you have to question if the true cost of the rotation have been factored in for long term sustainability.

The high fertility treatment is certainly one to watch, as we have seen some quite remarkable crop to crop responses, particularly around grain quality and establishment, which was not discussed in this paper. It is important to note the nutritional benefit of the manure has not been accounted for as yet within the N and P balance figures, however it is safe to assume that some benefit was to be expected after 60 t/ha was applied. Lab analysis indicate an approximate 53 kg/ha of N and staggering 608 kg/ha of P may have been applied, so with comprehensive soil analysis due again late this year, it will be interesting to see how much of that shows up and where in the profile.

Acknowledgements


Contact details

Darren Aisthorpe Department of Agriculture and Fisheries QLD 99 Hospital Rd Emerald QLD 4720 Ph: 07 4991 0808 Email: [email protected]

Varieties displaying this symbol beside them are protected under the Plant Breeders Rights Act 1994.

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On-farm grain storage: planning for profit Andrew Kotzur, Kotzur Pty Ltd

Key words

grain storage, silo, safety, design, facility planning

Take home message

Storing grain on farm should not be seen as a foregone conclusion, rather it must complement production and improve returns to the enterprise. Planning is an essential pre-cursor to a profitable, on-farm grain storage system. Planning does not necessarily define a complete facility, but rather provides for foreseeable requirements as well as keeping options open to accommodate changes in production and farming systems.

Introduction

It is thought that humans have been storing grain for about 11,000 years. The ability to store food (particularly grain) began the unlocking of human potential by freeing up time to think and pursue activities aside from the daily requirement to source food.

Grain storage is, in many ways, no different in today’s environment. Grain storage should free up time and resources as well as provide the tools which allow growers to pursue further opportunity. Overall, grain storage must improve efficiency and profitability of the farming enterprise.

Define the desired outcomes

Growers who are most successful in operating on-farm grain storage have a clear set of goals which define their on-farm grain storage system. These goals typically include some (or all) of the following;

• Managing the harvest efficiently and effectively

• Reducing and/or reallocating (in favour of the grower) supply chain costs

• Providing greater marketing opportunity for the crop produced

• Providing a “fodder” storage for stock production

• Adding value to the grain produced.

Design for safety and integrity

Safety is emerging as a key driver in decision making in rural industries. There remains significant opportunity for improvement in the grain storage space. Areas to consider with respect to safety include;

• Structural integrity

• Safe access (into and onto silos, to equipment) or eliminating “at height” operations

• Safe equipment (guarding, zero entry out-loading, electrical, pesticide application)

• Safe surrounds (traffic and equipment movement, powerlines).

Structural integrity in design is much harder for an end user to evaluate. Whilst we have various Australian Standards (such as AS 3774 – Loads on Bulk Solids Containers, and AS 1170.2 – Wind


27 Actions) relating to silos and structures, compliance is not mandatory and is not checked or enforced by any agency.

The areas to consider are those where we most commonly see failures;

• Footing design (designed for soil type, engineered for the structure and associated equipment)

• Silos engineered for bulk solids loading

• Wind loading.

Design for the crop production patterns

Grain production varies between regions and individual growers. A grain storage facility needs to be tailored to suit production. The design will take into account;

• Crop variety and production volume (total storage volume, silo size/number of segregations)

• Crop types (legumes require “gentler” conveying systems, aeration for oilseeds, hopper angles to suit grain types)

• Fill/empty cycles (high cycle silos will often be elevated/hopper bottom)

• Harvest patterns (intake rates, simultaneous intake and out turn)

• Future growth (more crop types, increased yields, increased farming area).

Design for efficiency and reliability

The efficiency of a grain storage facility is not easy to measure and needs to be considered together with cost (capital, running, maintenance). A high capacity, highly automated facility may be considered efficient, but not appropriate for the typical Australian grain production operation. To “future proof” the design stage would usually include the allowance to add dedicated conveying and automation at a later time. An efficient design will ensure;

• Grain inload rates should not impede the harvest process

• Flexibility around grain moisture levels (i.e. higher moisture harvest)

• Labour input is consistent with efficient resource allocation (and labour availability)

• Managing out turn to minimise time and labour. While intake at harvest is generally the high priority, being able to out turn quickly at any time reduces cost and stress on the farming operation

• Grain management in the facility is simple and effective. This applies to inspection and sampling, insect control, cleaning, drying, blending etc.

Reliability is one of the easier facility performance indicators to measure. Grain storage facilities need to be available as and when required. Breakdowns at harvest or repetitive reactive maintenance will add significantly to the cost of storing grain. With the increasing size of grain farming operations, we have seen capacities and throughput volumes increase to levels well in excess of those typical of the commercial facilities of years gone by. This means that facility design must consider the appropriateness of equipment, ease of maintenance, equipment alarms, condition monitoring, chute angles and wear points.

Design for quality and value add

If there has been an area where on farm storage has most evolved in the last 25 years, it is in the quality and value add space. This has been driven by increased crop diversity, crop value, crop

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pricing increments and increased grower awareness (in particular the extension work funded by GRDC). Quality and value can be realised through on farm storage in a number of ways;

• Maintaining grain moisture and temperature (spoilage, viability, colour, processing characteristics)

• Insect control (and chemical contamination)

• Drying

• Blending

• Cleaning

• Reduce physical damage

• Minimise cross contamination

• Provision of inventory control

• Provide traceability (identity preservation).

Further design considerations

There are a range of factors which are unique to each operation. These are used to optimise integration of the facility into the total farming system, to enable efficient management and to minimise capital cost. Whilst not conclusive, these factors are summarised as follows;

• Integration with existing grain storage – pros and cons. (Will the new storage be “Greenfield” or “Brownfield”)

• Site location relative to crop production, all weather road access, other farming activities (for supervision and operation) and residential precincts

• Soil type and drainage (both are important and have cost implications)

• Availability and size of mains power supply

• Land title boundaries (which may impact borrowings, future value as a separable asset)

• Future change and expansion plans.

Concluding comments

Like any farm asset, grain storage may be both an imperative (e.g. feed and seed storage) and discretionary (to improve efficiency). Like any asset, it must provide a return. It is vital to have a clear plan, with defined goals and expectations around farm grain storage development. This plan is the key driver in facility design.

Contact details Andrew Kotzur Kotzur Pty Ltd 60 Commercial St, Walla Walla , NSW, 2659 Ph: 02 6029 4700 Email: [email protected]


29 Grain storage – updates for fumigation in large silos and grain protectants

Philip Burrill, Greg Daglish and Manoj Nayak, DAF Qld.

Key words

phosphine fumigation, grain storage pest control, large silo fumigation, fumigation recirculation, grain protectant insecticides

GRDC codes

PRB00001, PBCRC3036, PBCRC3150

Take home message

• Successful grain storage is achieved by combining regular grain monitoring, good hygiene, aeration cooling, correct fumigation practices and use of grain protectants when appropriate

• In larger silos (150 – 2000t) recirculation of fumigation gases within the sealed silo, using a small fan, ensures rapid and uniform distribution of phosphine gas

• Without recirculation, it can take 2-5 days before the fumigant gas reaches all areas in a large silo, resulting in significant volumes of grain and insect pests being exposed to lower amounts of gas

• A significant R&D gap is the inability to effectively ‘monitor grain’ in the now common, large flat bottom silos. A simple, robust system for monitoring grain temperature, relative humidity, gas concentrations during fumigation and detection of the start of insect infestations is needed

• For grain protectant treatments, prior to applying, always read the label, check with potential grain buyers and seek advice if in doubt. Set up grain protectant spray application equipment to achieve good coverage and correct dose rate

Successful on-farm storage results

Fumigations and strategic use of grain protectant insecticides are only two of the five key tools used to maintain grain quality and achieve reliable pest control. These five practices (outlined below), when combined, form the foundation for successful grain storage. With a clear focus on these, a producer builds a reputation with grain buyers and end-users as a reliable supplier of quality grain.

Top five practices for successful grain storage:

1. Aeration: Correctly designed and managed, it provides cool grain temperatures and uniform grain moisture conditions. Aeration reduces storage problems with moulds and insect pests, plus maintains a range of grain quality attributes including germination, pulse seed colour, oil quality and flour quality.

2. Hygiene: A high standard of storage facility hygiene is crucial in keeping background pest numbers to a minimum and reducing the risk of grain infestation.

3. Monitoring: To prevent nasty surprises undertake monthly checking of grain in storage for insect pests (sieving / trapping) as well as checking grain quality and temperature. Keep monthly storage records, including any grain treatments applied.

4. Fumigation: In Australia, only fumigant gases (e.g. phosphine) are registered to deal with insect pest infestations in stored grain. To achieve effective fumigations the storage/silo must be sealable – gas-tight (AS2628) to hold the gas concentration for the required time.

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5. Grain protectants: Used on specific parcels of grain like planting seed held on farm, or bulk grain where potential grain buyers have agreed to its use, grain protectant sprays provide another line of defence against storage pests.

Fumigation of large silos (150 t or larger)

The first step – ensure “gas-tightness of storage”

Gases are the only registered products in Australia we can now use to control live insect pests when detected in grain. The most commonly used fumigant is a range of phosphine products (aluminium phosphide formulations) such as tablets or blankets. Other gases for grain pest control include sulfuryl fluoride (ProFume®), ethyl formate (Vapormate®) and methyl bromide.

The controlled atmosphere method is also effective, making use of either carbon dioxide or nitrogen gas. These are most commonly used for pest control in organic grains.

For any fumigation to be effective at controlling storage pests, the insects need to be exposed to a sufficient gas concentration (C), for a specified length of time (T). If this “C x T” exposure requirement is not achieved during the fumigation, insect survival is likely, especially of tolerant stages such as eggs and pupae. With fumigation failures, insects reappear in the grain within days or weeks.

Therefore, it is critical for Australian grain producers who store grain for more than a month, to have at least two sealable storages that meet the Australian silo sealing standard (AS2628).

A storage that is not gas-tight does not allow the fumigation “C x T” exposure level to be reached in all parts of a silo, whether large or small. Achieving reliable pest control results is not possible with gas leakage and air dilution. As well as not killing the pests, poor fumigation attempts also select for resistant insect populations.

To achieve effective fumigations, silos must be pressure tested to check they are sealed and gas-tight. This ensures they can hold high gas concentrations for the required time to kill pests.

Checking a large silo is ready for fumigation – useful equipment for pressure testing

• Portable leaf blower or small aeration fan -used to add air to silo for pressure tests. High volume, low pressure air is required. Standard air compressors are generally not suited to this task (see Figure 1).

• 50 mm poly fitting including a 50 mm shut-off value - fitted into the external section of silo aeration ducting. This is used to blow air into the silo.

• The silo’s pressure relief valve, or a clear U tube manometer, or better still, a digital manometer (e.g. Extech HD 755 Differential pressure manometer 0 – 0.5 psi) - Units seek to measure pressure changes within the 0 - 4 inches water gauge (w.g.) (0 - 1000 Pa) range. (see Figure 2)

• Spray bottle containing water & detergent - used to check for leaks. Often you can hear or feel air leaks from large silos during the pressure test.


31

Figure 1. Leaf blower and 50 mm gate valve fitted to aeration ducting used to pressurise a 1400

tonne silo for testing.

Figure 2. Using a U tube manometer to pressure test a silo. A digital manometer is also shown.

Pressure test – methods

New silos should be pressure tested by the silo supplier or manufacturer when completed on site. They should pass the Australian standard test (AS2628) to show they are sealable to a standard to allow for effective fumigation.

Sealable silos should then be pressure tested at least once a year to check for suitability for fumigations. Ideally, conduct a pressure test when a silo is full of grain. This places grain pressure on all silo surfaces and outlets, which is the condition the silo is in when you are fumigating.

Pressure tests should not be conducted when the sun is heating the silo’s external steel surfaces and warming / expanding the air inside the silo. Testing late in the afternoon when hot air in the silo is cooling is also a problem. A strong windy day is difficult, as silo surfaces are pushed around. Pressure test results under these conditions are meaningless.

Ideally test in the early morning before sunrise, or on a completely overcast day. In this way the air inside the silo is not heating or cooling (expanding or contracting) due to external conditions.

For small silos the pressure tests can be carried out by using a short burst (5 – 15 seconds) from the small aeration fan fitted to the silo. For larger silos a portable leaf blower to push air into the silo via a 50 mm fitting can be used to initially pressurise the silo for a test. (see Figure 1).

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The pressure decay time (250 Pa down to 125 Pa) can be checked using one of three options: the silo’s relief valves, a length of 15 mm diameter clear plastic tube in a “U” shape with water in it (manometer), or a digital manometer connected to the silo. See Figure 2. Also see GRDC Fact Sheet: “Pressure testing sealable silos” http://storedgrain.com.au/pressure-testing/ .

Common leakage points for large sealable silos

• Silo roof vents not sealing – maintenance or design problems

• Silo grain fill point at top of silo not sealing – damaged rubber seals on lid or sealing plate

• Grain outload auger at base of silo – leaking seal plate

• Bottom silo access manhole into silo - damaged seals, or poor design

• Sealing plate covers for the aeration fan’s intake, often poor design

• External aeration fan ducting, or the aeration fan itself not well sealed

• For some cone-based silos, weight of grain in the silo can break the seal of the bottom outlet – poor design

Fumigation recirculation – why is it important for fumigation of larger silos > 150 t

During fumigation, phosphine gas is typically liberated over 4 - 6 days from tablets or blankets that have been placed in the silo. This gas however, only moves slowly through the grain.

If fumigating a medium to large silo (150 – 2000 t), the gas may take 2 - 5 days to reach all parts of the silo. In large silo fumigations, this may result in some grain at the furthest distance from tablets, only getting 6 days of phosphine gas, instead of the required 10 days or longer exposure period. Six days is not enough time to kill all pest life cycle stages (especially tolerant eggs or pupae).

Figures 3 and 4 below show the difference in phosphine distribution speed in a silo with and without a fan. Phosphine concentrations required to kill all pests is a minimum of 200 ppm phosphine gas concentration for at least 10 days (horizontal blue line in Figures 3 and 4 below).

Figure 3. Phosphine gas concentrations at 7 points in a silo during fumigation of 1420 t of wheat. Phosphine blankets were placed in the silo headspace with no recirculation. It took up to 5 days for

all grain at the silo base to reach at least 200 ppm gas concentration.

http://storedgrain.com.au/pressure-testing/


33

Figure 4. Phosphine gas concentations in a silo (1420 t wheat) where a small fan was used to draw gas from blankets in the silo headspace and pump it into the silo base via aeration ducts for the first 5 days of fumigation. Gas concentration in all areas of the silo reached over 800 ppm within the first

24 hrs.

Figure 5. A small fan (F370 – 0.37 kW) used during the first 5 days of fumigation to recirculate

phosphine to give rapid uniform gas distribution in 1423 t wheat. See Figure 4.

Application options for fumigation recirculation

• For all fumigation recirculation systems, the sealable silo needs to be gas- tight so there is no gas leakage during fumigation. In Figure 4, “Base wall north” shows the impact of a leak at the silo manhole, causing large daily fluctuations in gas concentrations

• Phosphine blankets or tablets can be placed in the ‘silo headspace’. A small fan, sitting at the silo base, is connected to the headspace via 90 mm pipe plumbing coming down the silo wall

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from the roof. Phosphine gas is drawn from the headspace and pumped into the base of the silo via both aeration ducts (see Figure 5)

• For ground level application of tablets or blankets, a sealable ‘phosphine box’ can be plumbed into this system, either a moveable box, or mounted permanently on each silo

• Using a fan to force the phosphine gas movement around in silos during fumigation is generally recommended, rather than relying on a passive ‘thermosiphon’ approach and especially for medium and large silo fumigations (150 t or greater) or silos storing smaller grain sizes (e.g. millets, canola or lentils) that reduces air movement. Fan forced recirculation provides rapid gas distribution that is helpful where the grain type (e.g. oilseeds) typically absorbs higher amounts of phosphine during fumigation

Equipment for fumigation recirculation

• Sealable silo, gas tight, that passes a pressure test

• Plumbing pipes (90 – 100 mm) from silo roof to ground level. Use quality pipe, fittings and seals that will ensure many years of safe, gas- tight fumigations

• Small fan (e.g. Downfield F370 - 0.37 kW) to recirculate air. In most case this fan size will be suitable for both small & large silos. In trials (Figure 4 & 5) this fan size provided a complete silo air change every 12 hours for a full silo holding 1420 t of wheat

• Fittings for fan intake and outlet. Flexible hoses (50 – 100mm) couplings and gate valves

Fumigation recirculation - operations

• Pressure test the silo to check for leaks

• Follow all label directions and place tablets / blankets in the ‘headspace’ or ‘phosphine box’

• Run small recirculation fan for first 5 days of fumigation. Leave silo sealed for remaining days of fumigation exposure period as label requires (e.g. 7, 10, 20 days)

Fumigation notes

There are benefits to using the silo ‘headspace’ to locate the phosphine blankets or tablets. The large surface area of grain in the headspace provides safe, easy access for liberated gas to penetrate and diffuse into the grain.

Licenced fumigators may choose to use ‘bottled gas’ formulations of phosphine to undertake fumigations in large silos and other storage types, rather than using the solid phosphine formulations of blankets or tablets. An example is Cytec’s ECO2FUME® containing 20 g/kg phosphine in carbon dioxide handled in 31 kg liquefied gas cylinders. While applying the full dose of phosphine gas on day one into a storage has benefits, in most cases the use of a recirculation systems is still recommended to provide rapid, uniform gas distribution throughout the storage.

Warning: Always seek advice from a suitably qualified professional before fitting fumigation recirculation systems to silos / storages. Some systems that are currently sold are not recommended because of unsafe design features. Phosphine is not only a toxic gas but can be flammable and explosive if restricted in a small area or used in a manner that causes gas concentrations to rise quickly to high levels. Follow label directions and seek advice.

R&D gap: One of the significant R&D gaps is the inability to effectively ‘monitor grain’ in the now very common, large flat bottom silos. We require simple but robust equipment to monitor grain temperatures, relative humidity, gas levels during fumigation and also clever ways of detecting the start of insect infestations in storages.


35 Products such as OPI grain cables http://www.advancedgrainmanagement.com/products/ are a good starting point, however in previous research trials in Australia we found OPI moisture cables fitted to silos failed after a standard phosphine fumigation. We assume the corrosive phosphine gas had entered via the relative humidity orifice on cable sensors. We need regular, reliable monitoring of grain in these large storages.

Profume fumigation use in Australia

ProFume® (sulfuryl fluoride gas) has only been available for use in Australia for a relatively short time, 10 years. Phosphine fumigation products have been used to control grain pests for well over 50 years.

ProFume is manufactured and supplied by Douglas Products™ based in America. A-Gas Rural® based in South Australia has the importing and distribution rights for ProFume. They also provide specialist product and safety training to licenced fumigators, allowing them to purchase and undertake ProFume fumigations.

ProFume can only be applied by a licenced fumigator to control storage pests in cereal grains. It has a valuable role in the grain industry as an alternative fumigation product to rotate with phosphine to help manage insect pest resistance in cereal grains.

Ten years ago, a very high level of phosphine resistance was first identified at a number of bulk handling sites in Eastern Australia. It occurred in a species of one of the flat grain beetles, also known as rusty grain beetle (Cryptolestes ferrugineus) (see Figure 6). Since then it has become more common, although to a lesser extent on farms.

If growers identify flat grain beetles surviving what should have been a successful phosphine fumigation, we would recommend sending in a sample of these insects to DAF’s postharvest laboratories in Brisbane for testing. If found to be this resistant strain, then a ProFume fumigation may be recommended.

For further details on ProFume use, read the label and search ‘ProFume’ on GRDC’s web site. https://grdc.com.au/

Figure 6. Flat grain beetles, Cryptolestes spp.

Grain protectant sprays update

Warning

Grain protectant notes below do not apply to the grains industry in Western Australia where their use is restricted. In all cases, product labels are to be used to determine correct use patterns.

http://www.advancedgrainmanagement.com/products/

https://grdc.com.au/

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When to use grain protectants

• Grain protectant sprays are not to be used to disinfest grain. When live insects are detected, fumigation in a sealed silo is required for effective control

• Typically, protectant sprays are applied to cereal grain at harvest time as grain is augered into storages, providing storage pest protection for 3 - 9 months. Protectants are effective at controlling insects as they invade the grain during storage, or the immatures (eggs, larvae or pupae) produced by such insects

• With many domestic and export markets seeking grain supplies which are “pesticide residue free” (PRF), always talk to potential grain buyers / traders prior to applying grain protectant sprays

• Except for some chlorpyrifos-methyl products in lupins in Victoria only, NO protectant sprays can be applied to pulses and oilseeds

Common ‘on-farm’ uses for grain protectants

• Planting seed held on-farm – wheat, barley, oats

• Grain held for an extended time in non-sealable storages (not suited for fumigation) and when the grain buyer has agreed to grain protectant use that is in line with directions for use on the registered product label

• Grain held on-farm as feed for livestock with agreement from livestock agent or buyer and is in line with directions for use on the registered product label

Grain protectant choices

Examples of two products, which include a partner product, to control the main storage pest species:

1. Conserve Plus™ Grain Protector – a.i. 100 g/L spinosad, 100 g/L s-methoprene. Used in combination with a compatible organophosphate (OP) product such as chlorpyrifos-methyl (ReldanTM), or fenitrothion.

For label and details on product use, see: http://www.dowagro.com/en-au/australia/product_finder/insecticides/conserve-plus

Key recommendations

• Always add the OP partner to Conserve Plus so the rice weevil (Sitophilus oryzae) is controlled

• Spray equipment calibration and application care are critical to achieve correct dose and uniform coverage on grain

• If treated grain is exposed to light, for example a semi open grain shed, cover the grain surface with a tarp or 80 - 90% shade cloth. Sunlight breaks down Conserve Plus over time

• Take care to read notes on the web site (above) and seek advice when purchasing Conserve Plus

2. K-Obiol® EC Combi, synergised grain protectant – a.i. 50 g/L deltamethrin, 400 g/L piperonyl butoxide. Used in combination with an organophosate (OP) partner e.g. chlorpyrifos-methyl or fenitrothion.

For label and details on product use, see: https://www.environmentalscience.bayer.com.au/K-Obiol/About%20K-Obiol

http://www.dowagro.com/en-au/australia/product_finder/insecticides/conserve-plus


https://www.environmentalscience.bayer.com.au/K-Obiol/About%20K-Obiol



37 Key recommendations

• To control rice, maize and granary weevils (Sitophilus spp.) add a recommended OP partner (e.g. chlorpyrifos-methyl or fenitrothion) to the tank mix

• To ensure effective pest control and that MRL’s are not exceeded, calibrate spray equipment to achieve correct dose rate & uniform coverage on grain

• Grower users are required to complete a brief (approx. 60 minutes) online training course to be an ‘approved user’ prior to purchase of K-Obiol® EC Combi. See above website

Insect resistant management

If possible, aim to rotate chemical active ingredients for storage pest control at your storage facility. Example, for two years use Conserve Plus™ product combination, followed by one or two years of K-Obiol® EC Combi.

Please read and follow all label recommendations and ensure that the product is registered for use in your state prior to application of any product.

Application for grain protectants

Grain protectant application requires care to achieve the correct dose and uniform grain coverage. This leads to effective pest control results and ensures MRL’s are not exceeded. See Figure 7 below.

• Auger’s grain transfer rate. Ensure you have good understanding of the grain flow rate, tonnes per hour, for the height the auger will be operating at

• Calibrate your spray application unit with water and check appropriate nozzles and spray pressure are used to achieve the required application of 1 litre of spray mixture per tonne of grain

Figure 7. Spray application equipment designed for good coverage by applying treatment at two

points in the auger

Further information

GRDC booklet – Fumigating with Phosphine other fumigants and controlled atmospheres: http://storedgrain.com.au/fumigating-with-phosphine-and-ca/

http://storedgrain.com.au/fumigating-with-phosphine-and-ca/

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GRDC Fact sheet – Pressure testing sealable silos: http://storedgrain.com.au/pressure-testing/

GRDC video – Fumigation recirculation: http://storedgrain.com.au/fumigation-recirculation/

Dow™ AgroSciences - Conserve Plus™ Grain Protector: http://www.dowagro.com/en-au/australia/product_finder/insecticides/conserve-plus

BAYER CropScience - K-Obiol® EC Combi: https://www.environmentalscience.bayer.com.au/K-Obiol/About%20K-Obiol

Acknowledgements The authors acknowledge the research support by the past Plant Biosecurity Cooperative Research Centre, of which GRDC was a partner, specifically projects PBCRC3036 and PBCRC3150 under which the fumigant research was conducted. The authors would also like to thank DAF’s Postharvest research team members, GRDC’s national grain storage extension team, along with valued support from growers and other industry collaborators.

Contact details

Philip Burrill Department of Agriculture & Fisheries, AgriScience Qld. Hermitage research facility, 604 Yangan road, Warwick Qld. 4370 Mb: 0427 696 500 Email: [email protected]

® Registered trademark TM Trademark

http://storedgrain.com.au/pressure-testing/

http://storedgrain.com.au/fumigation-recirculation/



mailto:[email protected]


39 Helicoverpa armigera resistance management in grains

Melina Miles, DAF Qld.

Key words

Helicoverpa armigera, resistance, chickpeas, mungbeans, soybeans

GRDC code

DAQ00196, UM00048 (NIRM)

Take home message

The H. armigera resistance management strategy in grains is designed to prolong the useful life of the newer chemistry currently available to pulse growers. Familiarise yourself with the strategy and the full range of options available for Helicoverpa control in chickpeas, mungbeans and soybeans. Consider what products you will use if a second spray is required in these crops.

The Helicoverpa armigera resistance management strategy (RMS)

This material has been extracted from the “Science behind the strategy” document available at https://ipmguidelinesforgrains.com.au/ipm-information/resistance-management-strategies/. The RMS has been developed by the National Insecticide Resistance Management (NIRM) group, a part of the Grains Pest Advisory Committee (GPAC).

General rationale for the design of the strategy Chickpeas and mungbeans are currently, and for the foreseeable future, the most valuable grains crops influenced by the RMS. Therefore, the RMS is primarily focused on insecticide Modes of Action (MoA) rotation in these systems and is built around product windows for Altacor® and Steward® because:

1. Altacor® (chlorantraniliprole) is at risk from over-reliance in pulses, but resistance frequencies are currently low

2. Steward® (indoxacarb) is at risk due to genetic predisposition (high level genetic dominance and metabolic mechanism) and pre-existing levels of resistance in NSW and QLD (with elevated levels in CQ during 2016-17). In addition, the use of indoxacarb in pulses is expected to increase as generic products come on to the market

In future, the RMS may include windows for other products e.g. Affirm® (emamectin benzoate), Success Neo® (spinetoram), and other new products that come to market, if their use patterns necessitate management. There are two RMS regions, each with their own RMS designed to make the most effective products available when they are of greatest benefit, whilst minimising the risk of overuse:

1. Northern Grains Region: Belyando, Callide Central Highlands & Dawson (Table 1) 2. Central Grains Region: Balonne, Bourke, Burnett, Darling Downs, Gwydir, Lachlan,

Macintyre, Macquarie & Namoi (Table 2)

• The RMS provides windows-based recommendations common to Southern QLD, Central & Northern NSW because H. armigera moths are highly mobile and have the capacity to move between these regions, potentially increasing the risk of further exposing populations of H. armigera previously selected for resistance in other areas.

https://ipmguidelinesforgrains.com.au/ipm-information/resistance-management-strategies/

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• No RMS is currently proposed for the Southern and Western grain regions (Victoria, South Australia and Western Australia). Biological indicators are that the risk of H. armigera occurring in winter crops, at densities where control failures may occur, is presently considered low. Helicoverpa control in summer crops in these regions should use the Central Grains region RMS.

Use of broad-spectrum insecticides The early use of synthetic pyrethroids (SPs) in winter pulses is a strategy adopted in southern Qld and northern NSW where the assumption is made that early infestations of Helicoverpa will be predominantly H. punctigera which are susceptible to SPs. Similarly, the use of carbamates to delay the application of Group 28 or Group 6 products, carries risks. If adopting this strategy, be aware of the following risks:

1. Recent monitoring with pheromone traps has shown H. armigera to be present in all parts of the northern grains region from July-August (https://thebeatsheet.com.au/ )

2. Reduced efficacy of SPs and carbamates against H. armigera can be masked when treating very low population densities (< 3/sqm)

3. If H. armigera are present, even at low levels in a population treated with SPs and carbamates, the treatment will select for further resistance. Whilst initial applications may be effective, later treatments may be significantly less effective.

https://thebeatsheet.com.au/

Table 1. Grains resistance management strategy for Helicoverpa armigera across Australia. Best practice product windows and use restrictions to manage insecticide resistance in H.armigera. Northern Region: Belyando, Central Highlands, Dawson and Callide.

Insecticide June July Aug Sept Oct Nov Dec Jan Feb Mar Apr May 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

Bacillus thuringiensis

Helicoverpa viruses

Paraffinic oil (Note 1)

Chlorantraniliprole (Note 2, 3)

Indoxacarb (Note 4)

Spinetoram (Note 2, 4, 5)

Emamectin benzoate (Note 2, 4, 5)

Carbamates (Note 2, 4 6)

Pyrethroids (Note 2, 4, 7)

No restrictions DO NOT USE during this period No more than one application per crop per season

No more than two applications per crop per season

ADDITIONAL INFORMATION Notes:

1. Some nC27 paraffinic spray oils can be used to suppress Helicoverpa populations and are best used as part of an IPM program. 2. Observe withholding periods (WHP). Products in this group have WHP 14 days or longer. 3. Maximum one spray of chlorantraniliprole alone or in mixtures per crop per season. 4. Refer to label for warning of insecticide risk to bee populations. 5. Maximum two consecutive sprays alone or in mixtures per crop per season. 6. MODERATE RESISTANCE IS PRESENT IN H.ARMIGERA POPULATIONS – FIELD FAILURES LIKELY. 7. HIGH RESISTANCE IS PRESENT IN H.ARMIGERA POPULATIONS – FIELD FAILURES EXPECTED!

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Table 2. Grains resistance management strategy for Helicoverpa armigera across Australia. Best practice product windows and use restrictions to manage insecticide resistance in H.armigera. Sth QLD, Central & Nth NSW Regions: Balonne, Bourke, Burnett, Darling Downs, Gwydir, Lachlan, Macintyre, Macquarie & Namoi.

Insecticide June July Aug Sept Oct Nov Dec Jan Feb Mar Apr May 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4

Bacillus thuringiensis

Helicoverpa viruses

Paraffinic oil (Note 1)

Chlorantraniliprole (Note 2, 3)

Indoxacarb (Note 4)

Spinetoram (Note 2, 4, 5)

Emamectin benzoate (Note 2, 4, 5)

Carbamates (Note 2, 4 6)

Pyrethroids (Note 2, 4, 7)

No restrictions DO NOT USE during this period No more than one application per crop per season

No more than two applications per crop per season

ADDITIONAL INFORMATION Notes:

1. Some nC27 paraffinic spray oils can be used to suppress Helicoverpa populations and are best used as part of an IPM program. 2. Observe withholding periods (WHP). Products in this group have WHP 14 days or longer. 3. Maximum one spray of chlorantraniliprole alone or in mixtures per crop per season. 4. Refer to label for warning of insecticide risk to bee populations. 5. Maximum two consecutive sprays alone or in mixtures per crop per season. 6. MODERATE RESISTANCE IS PRESENT IN H.ARMIGERA POPULATIONS – FIELD FAILURES LIKELY. 7. HIGH RESISTANCE IS PRESENT IN H.ARMIGERA POPULATIONS – FIELD FAILURES EXPECTED!

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Addressing questions on the RMS

The number of uses in the RMS is more restrictive than stated on the Steward® and Altacor® labels, why?

To avoid repeated use of either Steward® or Altacor® within the use window, the number of allowable applications is 1 per crop. In some instances, the label registration may allow for more than one application; the recommendations were developed in consultation and supported by the chemical companies. It is anticipated that changes to product labels will follow to ensure consistency between labels and the RMS.

Does the RMS impact on recommendations for insecticide use in cotton and other grain crops?

The RMS is not intended to compromise the ability of the cotton industry to use any products registered for Helicoverpa in Bollgard®. This is because selection for insecticide resistance is considered low due to the high likelihood that survivors of conventional sprays used in Bollgard would be killed by Bt toxins expressed in plants. For further information go to: http://www.cottoninfo.com.au/publications/cotton-pest-management-guide.

Similarly, the RMS does not attempt to align the use of the Group 28s in mungbeans and chickpeas with use in other grain crops or horticulture. To do so would add a level of complexity that would make the RMS impractical.

Shouldn’t other MoAs be windowed to prevent the potential development of resistance to these products?

There is little evidence to suggest that other products should be windowed now to slow the development of future resistance. Both Affirm® (emamectin benzoate) and Success Neo® (spinetoram) show no sign of reduced susceptibility in testing (L. Bird, CRDC data). This result is consistent with the relatively limited use of these products in the grains industry to date. If a shift in susceptibility is detected in future testing, or the frequency with which they are used increases, it is the intention that the product/s will be windowed to limit selection pressure.

The SPs and carbamates are not windowed because there are already well established, relatively stable moderate-high levels of resistance to these MoAs and limiting their use will not change this situation.

By restricting the use of just the ‘at risk’ products, keeping the RMS as simple as possible, and allowing maximum choice of registered products, we anticipate that the grains industry will be more inclined (and able) to use the RMS.

The relative efficacy of the ‘softer’ options for Helicoverpa control in mungbeans and chickpeas – you aren’t totally reliant on Group 28s.

In 2017, QDAF Entomology undertook a number of trials to compare the knockdown/contact efficacy, and residual efficacy (persistence in the crop) of Altacor®, Steward®, Affirm® and Success Neo®. The purpose of these trials was to provide agronomists and growers with information on how well each of the products worked, and to provide confidence to use another option, rather than relying solely on the Group 28 products.

The results show that these products are equally effective on 3rd, 4th or 5th instar larvae that receive a lethal dose of the product – as would be achieved with good spray coverage (Figure 1a). But of course, there is considerable benefit in products persisting in the crop to control larvae that may hatch after the spray, or emerge from flowers, buds or pods where they may have been protected. The long residual efficacy of Steward® and now Altacor ® has been a major factor in their popularity.

http://www.cottoninfo.com.au/publications/cotton-pest-management-guide


45 The data in Figure 1b shows the relative efficacy of these products from 0 – 20 days after treatment in the field (at 5-day intervals).

For more information on the relative performance of these products in terms of feeding potential and recognising larvae affected by the different insecticides, see recent articles on the Beatsheet blog (https://thebeatsheet.com.au/).

Figure 1. Relative efficacy (a) direct contact and (b) residual, of softer options for Helicoverpa control

in chickpea and mungbean crops.

Another representation of the relative efficacy of the products is provided below (Figure 2) and shows how significantly the feeding (damage potential) of 3rd and 5th instar larvae was affected in the 24 hours post treatment with each insecticide. The graph clearly shows that feeding was significantly reduced in all treatments, compared with the controls. It also shows how much more feeding a 5th instar larva is capable of than a 3rd – emphasising the importance of controlling larvae before they are medium-large.

https://thebeatsheet.com.au/

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Figure 2. Soybean leaf area consumed in 24 hours post treatment by 3rd and 5th instar Helicoverpa

larvae. The leaf area consumed is representative of the relative damage potential of the larvae.

Acknowledgements


Information on the H. armigera RMS is extracted from material prepared by NIRM to support the implementation of the RMS. The authors acknowledge the contribution of NIRM members to the development of this material.

We are grateful to the growers who allow us access to their farms and crops, and to the agronomists who assist us in locating potential field sites. We also thank the many growers and agronomists who share with us their experiences and insights into the issues they face and the practicalities of the management options we propose.

Adam Quade and Trevor Volp provided the technical expertise required to undertake the feeding trials.

NIRM (2018) Science behind the Resistance Management Strategy for Helicoverpa armigera in Australian grains. https://ipmguidelinesforgrains.com.au/ipm-information/resistance-management-strategies/

Contact details

Melina Miles Queensland Department of Agriculture and Fisheries 203 Tor St, Toowoomba. QLD 4350 Mb: 0407 113 306 Email: [email protected]





47 Chaff lining and chaff tramlining to reduce problem weed populations

Annie Ruttledge1, Paul McIntosh2, John Broster3, Annie Rayner4, Kerry Bell1, Michael Walsh4, Michael Widderick1

1 Department of Agriculture and Fisheries, Toowoomba 2 Pulse Australia and the Australian Herbicide Resistance Initiative, Highfields 3 Charles Sturt University, Wagga Wagga 4 University of Sydney, Narrabri

Key words

Harvest weed seed control, chaff lining, chaff tramlining, chaff decks, stripper fronts.

GRDC code

US00084 (Innovative Crop Weed Control for Northern Region Cropping Systems)

Take home message

• Burial of weed seeds under chaff can reduce seedling emergence, but the amount of suppression depends on weed type, chaff type, and amount of chaff cover

• There is no evidence that weed seeds rot more quickly in chaff tramlines; but it’s likely that environmental conditions and weed seed type could make a difference

• Stripper fronts and conventional harvest fronts can capture similar percentages of weed seeds providing the header is set up and used appropriately

• Chaff lining and chaff tramlining won’t totally prevent weed emergence – be prepared to use other measures (e.g. spraying the tramlines with a shielded sprayer)

• The best reason to use chaff lining or chaff tramlining is to concentrate weed seeds into a narrow area for easy follow-up

Background

Herbicide resistance is a major concern for northern region crop production due to the increasing frequency of resistance in key weeds. Non-herbicide weed management alternatives are needed to delay the spread and onset of further herbicide resistance (Walsh et al., 2013). One such alternative is harvest weed seed control (HWSC). Harvest weed seed control (HWSC) refers to a suite of management practices all of which target the seed of weeds present at harvest time and borne at harvestable height (typically around 15cm or more above ground height, depending on header set-up).

Current HWSC systems include narrow windrow burning, chaff tramlining/chaff lining, chaff carts, bale direct and seed destruction (Walsh et al. 2013). Chaff lining and chaff tramlining have potential for wide-spread adoption in northern Australia owing to their low cost and ease-of-implementation relative to some other HWSC practices. Chaff tramlining is the practice of concentrating the weed seed bearing chaff material on dedicated tramlines in controlled traffic farming (CTF) systems, typically using a chaff deck to deposit chaff into 2 lines (one per wheel track). Chaff lining is a similar concept, where the chaff material is concentrated using a chute into single narrow row between stubble rows directly behind the harvester (i.e. not specifically onto the tramlines).

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Weed seed collection

The proportion of weed seed entering the front of the harvester is key to the efficacy of harvest weed seed control methods. An increasing number of Australian grain growers are adopting stripper harvester fronts. These fronts use rows of fingers on a spinning rotor to pluck grain heads and pods from mature crop plants. Conventional (known as Draper) header fronts cut and collect the entire plant above the harvest height. Stripper fronts leave more stubble standing. By reducing the quantity of material being processed, harvester stripper fronts increase the speed and efficiency of harvesting. Because HWSC relies on weed seeds entering the harvester, it is important to know whether stripper fronts can achieve weed seed collection proportions similar to conventional fronts.

The weed seed collection effectiveness of stripper and conventional harvester fronts was compared in wheat paddocks on two different farms near Wagga Wagga (Figure 1). At Site 1 the proportion of annual ryegrass seeds collected by the stripper front was identical to that of a conventional front. In contrast, at site 2 a lower proportion of ryegrass seed was collected by the stripper front. Row spacing was greater at this site and the harvester was running faster and higher than at Site 1, which could have reduced the seed collection and therefore HWSC efficacy.

Figure 1. Percentage of ryegrass seed collected by stripper front and conventional front at two

locations (means with same letter are not significantly different) (Broster et al., 2018).

These results suggest that, with due diligence, a stripper front can collect a similar proportion of annual ryegrass seeds as a conventional front and can be used in conjunction with HWSC systems.

Fate of weed seeds

Weed suppression

There have been anecdotal reports that weed seeds die or fail to emerge from chaff lines and chaff tramlines. Pot trials were conducted at three locations (Toowoomba, Wagga Wagga and Narrabri) to investigate the influence of wheat, barley, canola and lupins chaff on the seedling emergence of annual ryegrass (Broster et al., 2018; Ruttledge et al., 2018). Although the amount of chaff required to significantly reduce germination differed between studies, increasing amounts of wheat chaff reduced annual ryegrass germination and emergence at all three locations. Wheat chaff at 24 t/ha reduced annual ryegrass emergence by approximately 15 to 35% across the three pot trials.

The type of chaff can also influence emergence of weed seedlings. A pot study conducted at Wagga Wagga explored the emergence of annual ryegrass under 4 chaff types (barley, canola, lupins and


49 wheat). While there was an interaction between crop type and chaff amount (Figure 2), overall barley inhibited emergence better than wheat, and both were better than canola and lupins. For each chaff type the effect of rate was significant (i.e. for all 4 chaff types, weed emergence decreased as the amount of chaff increased).

Figure 2. Emergence of annual ryegrass through wheat, lupin, barley and canola chaff at 8 different

rates (t/ha) in a pot trial conducted at Wagga Wagga, NSW (Broster et al., 2018).

Pot experiments conducted in Toowoomba compared the emergence of common sowthistle under wheat and barley. In the first study, wheat chaff suppressed emergence more than barley chaff, although there was no significant difference between the two chaff types. In a subsequent repeat of this pot study, wheat did have significantly greater suppression of common sowthistle compared with barley chaff (Figure 3). Possible reasons include physical or chemical differences between the wheat and barley chaff used in this experiment. In both studies, 12 t/ha was sufficient to significantly and dramatically reduce sowthistle emergence in the wheat chaff treatment.

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Figure 3. Emergence of common sowthistle through barley and wheat chaff (combined data) at 9

different rates (t/ha) in a pot experiment conducted at Toowoomba (Ruttledge et al., 2018).

Weed seed decay

There are anecdotal reports of weed seed rot in chaff lines/chaff tramlines. On-farm research conducted on the Queensland Darling Downs has compared the viability of weed seeds inside and outside of chaff tramlines. Seeds of annual ryegrass, sowthistle, turnip weed and wild oats were placed in fibreglass mesh bags and left for 6 months in 2 barley paddocks (1 harvested using a conventional draper front and one harvested using a stripper front) and in a wheat paddock (conventional front only). At the end of this period the viability of the remaining seeds was determined. There were no significant differences between the seeds placed inside tramlines and those placed outside of tramlines, for any of the 3 paddocks (Figure 4). In other words, weed seeds placed in tramlines did not appear to decay any faster than those left on the soil surface outside of tramlines.


51

Figure 4. Viability of weed seeds collected after 6 months in barley and wheat fields, both under

chaff tramlines and outside tramlines (control treatment) (Ruttledge et al., 2018).

However, multiple factors are involved in weed seed decay, including temperature, moisture, chaff type and amount, and characteristics of the weed seeds themselves. In other words, what happens to weed seeds in chaff lines or chaff tramlines is likely to vary according to site, season, crop type and weed type.

Chaff production

As outlined above, research indicates that weed suppression increases with the amount of chaff cover. The amount of chaff that accumulates in chaff tramlines or chaff lines could also have implications for other farming operations (e.g. planting).

It is unlikely that all crops types will have the same chaff percentage. A barley crop is likely to have a lower chaff proportion than a wheat crop. With a 12 m wide conventional harvester forming a chaff line 30cm wide and a chaff proportion of 0.3 (or 30%), then 42 t/ha of chaff equates to a 3.5 t/ha crop (Figure 5). However, if the chaff proportion is 0.2 (or 20%) then 42 t/ha equates to a 5.25 t/ha crop. Conversely, with a chaff proportion of 0.5 (50%), only 2.1 t/ha crop is required to produce a chaff line of 42 t/ha (Broster et al., 2018). It should be noted that in chaff tramlining, two chaff lines are formed, which means that only half the amount of chaff residue is deposited in each line.

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Figure 5. Estimated crop yield for various chaff rates at different chaff proportions for 12 m wide

harvester and 0.3m chaff line (Broster et al., 2018). Note: This was calculated regardless of header type, but the different chaff proportions could relate

to the different fronts, e.g. 20% = stripper front, 40% = draper front.

The type of header front is also important in determining the amount of chaff exiting the header. Research has established that draper fronts produce more than twice the amount of chaff compared with a stripper front (Figure 6). This is likely due to the larger amount of crop material collected by a draper front compared to a stripper front, resulting in a significant amount of straw material exiting in the chaff fraction when using a draper front (Broster et al., 2018).

Figure 6. Amount of chaff fraction (kg) produced when using two different harvester fronts (means

with same letter are not significantly different) (Broster et al., 2018).


53 Conclusions and recommendations

Chaff lining and chaff tramlining are forms of harvest weed seed control with the potential to capture weed seeds at harvest time and concentrate them in the chaff residues. Weed seeds buried in chaff can have reduced emergence, but the extent of suppression depends on the characteristics of the chaff (crop type, chaff thickness) and also on the weed species. Depending on the seed ecology of weed species, some weeds will be more susceptible to burial in chaff than other weeds.

Research conducted to date does not indicate that weed seeds rot more quickly when concentrated in chaff tramlines. However, the fate of weed seeds is strongly determined by environmental conditions (moisture, temperature, predation etc.) as well as the characteristics of the weed seeds themselves. This means that the extent and rapidity of seed decay is likely to vary from site to site, season to season, and between chaff type and weed type.

The amount of chaff deposited in chaff tramlines is likely to influence the fate of weed seeds, and this is in turn dependent on crop type, planting density, row spacing, header set-up, harvest speed, and the type of header front used (with less chaff produced by a stripper front).

The efficacy of HWSC techniques, including chaff lining and chaff tramlining, will depend on maximum capture of weed seeds at harvest time. The use of stripper fronts is compatible with HWSC but care is needed in harvester operation to maximise seed collection. Header settings (e.g. height) and harvest speed can all influence the efficacy of weed seed collection by both conventional and stripper harvester fronts. Further research is needed to determine how agronomic considerations (e.g. crop architecture and planting design) can optimise weed seed collection during harvest. Additionally, attributes of the weed species, the weather and the amount of seed shed which has occurred before harvest will have an impact on the accuracy of weed seed collection using HWSC practices (Broster et al., 2018).

In summary, weed seeds captured during harvest and concentrated into chaff residues can have reduced emergence due to the presence of crop chaff, especially at high chaff loads. It is evident that weed seeds of key northern species can remain viable in a tramline environment for 6 months, and potentially longer (work being conducted at present will establish the viability of seeds after 11 months in the field). However, by using chaff tramlining or chaff lining, weed seeds captured during harvest are concentrated into one or two lines per header pass, where they can be monitored and treated in targeted weed control strategies (e.g. using high rates and a shielded sprayer).

Acknowledgements The research presented in this paper was 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. The authors also gratefully acknowledge the following people for their assistance with the establishment and assessment of experiments: Allison Chambers (CSU), Linda Heuke (USyd), Shona Robilliard (USyd), a number of CSU students, Onella Cooray (QDAF), Jeff Werth (QDAF) and Adam Jalaludin (QDAF). The authors would also like to thank Kylie and Peter Bach for hosting the QLD trial site.

References Broster, J.C., Rayner, A., Ruttledge, A., Walsh, M.J. (2018). Impact of stripper fronts and chaff lining on harvest weed seed control. Available at https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/07/impact-of-stripper-fronts-and-chaff-lining

Heap, I. The International Survey of Herbicide Resistant Weeds. Available at www.weedscience.com

Ruttledge, A., Widderick, M., Walsh, M., Broster, J., Bell, K., Rayner, A., Jalaludin, A., Cooray, O., Heuke, L., Robilliard, S. and Chambers, A., The efficacy of chaff lining and chaff tramlining in

https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/07/impact-of-stripper-fronts-and-chaff-lining

https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/07/impact-of-stripper-fronts-and-chaff-lining

http://www.weedscience.com/

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controlling problem weeds (2018). Available at https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/07/the-efficacy-of-chaff-lining-and-chaff-tramlining-in-controlling-weeds

Walsh M.J., Newman, P., and Powles SB (2013). Targeting weed seeds in-crop: A new weed control paradigm for global agriculture. Weed Technol. 27:431-436

Contact details

Paul McIntosh Pulse Australia / Australian Herbicide Resistance Initiative (Partner – Broadleaf Cropping Alliance) Address: 7 Berghofer Drive, Highfields Qld 4352 Mb: 0429 566 198 Email: [email protected]

Annie Ruttledge DAF QLD PO Box 2282, Toowoomba Qld 4350 Mb: 0481 253 930 Email: [email protected]

https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/07/the-efficacy-of-chaff-lining-and-chaff-tramlining-in-controlling-weeds




55

Sowthistle biology – management & resistance status Paul McIntosh (Australian Herbicide Resistance Initiative)

Key words

sowthistle, milkthistle, herbicide resistance, northern region, seed production, minimum tillage, zero tillage, Sonchus oleraceus

Take home message

• Sowthistle (Sonchus oleraceus) can produce up to 200,000 seeds per well grown adult plant.

• Seed has no or minimal dormancy

• Zero or minimum till favours all year round germination of sowthistle

• Use all methods to stop seed set and rundown seed bank reserves of this predominate surface germinator

• Each seed has a feathery pappus to aid more distant dispersal by wind

Survey of glyphosate resistance in Queensland and New South Wales

Sowthistle is one of the most widespread weeds in the northern cropping region and has the ability to germinate at most times during the year.

In approximately 600 paddock surveys in Qld and NSW;

o Winter 2016/17- 202 paddocks had sowthistle present

o Summer 2017/18- 11 paddocks had sowthistle present

Distribution

Annual sowthistle is widely distributed in Australia. Virtual herbarium records indicate the presence of this weed in all Australian states and territories. (Figure 1).

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Figure 1. Distribution of annual sowthistle across Australia

Figure 2. Sowthistle distribution in the northern grain cropping region (Source: Broster J (2018), Charles Sturt University and Jalaludin A, Queensland Department of Agriculture and Fisheries,

(2018)).


57 The recent development of populations that are resistant to glyphosate has the potential to greatly complicate and increase cost associated with management of this weed – particularly in the fallow.

Figure 3. Map of glyphosate resistant and susceptible sowthistle (Sonchus oleraceus) populations

across northern grain cropping region. All populations remained sensitive to 2,4-D amine. (Source: Broster J (2018), Charles Sturt University and Jalaludin A, Queensland Department of

Agriculture and Fisheries, (2018)).

Biology and management of annual sowthistle (Sonchus oleraceous L.)

Figure 4. Sowthistle (photo credit: State of Queensland 2015, Department of Agriculture & Fisheries)

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Salient features

• Annual sowthistle is a broad leaf weed and member of the ‘Asteraceae’ family

• Abundant seed production, wind dispersal, lack of seed dormancy and ability to germinate under varying light and temperature conditions, soil pH and salinity and its preference to germinate at or very close to the soil surface, can lead to a further increase in the predominance of this weed – particularly in minimum and zero tillage crop systems

• Management should focus on diversifying the type of control options by including competitive crops in rotation that also allow the use of non-glyphosate based control strategies

• Annual sowthistle germination, biomass production and total weed seed production rates are significantly reduced by crop competition. Crop competition can be enhanced by selecting more competitive crop types, using narrow row spacing and high seeding rate

• In a fallow environment, sowthistle has the capacity to deplete substantial soil moisture

• Annual sowthistle naturally exhibits a level of glyphosate tolerance. This tolerance has evolved with populations now confirmed as resistant to glyphosate. Risk assessment studies indicate that this weed has the potential to rapidly evolve resistance to glyphosate

• Sowthistle is a small seeded surface germinating weed which therefore struggles to germinate from depth. As such, tillage based systems where a substantial amount of weed seed is placed at depth reduce weed emergence

• Control of sowthistle products with residual products can be highly effective due to the low levels of seed dormancy and persistence

Major morphological features

Annual sowthistle develops bigger basal leaves (up to 30 cm). New leaves added as the plant grows are progressively smaller. Leaf development is alternate with leaves clasped around the stem. Plants can grow up to 1.5 m high. Stems are hollow and will ooze a white sap when broken. Flowers are yellow (dandelion like) and, when mature, develop into a small tuft of white flower head suited to wind dispersal (Figure 5). The yellow flowers and seed head closely resemble another species called ‘prickly sowthistle’ (Sonchus asper L.). As the name indicates, prickly sowthistle has spiny leaves and can be easily distinguished from annual sowthistle (Figure 6).


59

Figure 5. Annual sowthistle with white flower head and individual seeds with white pappus (Source:

B. Chauhan)

Figure 6. Prickly sowthistle (A) and annual sowthistle (B) bearing flower heads (Source: B. Chauhan)

Germination Previous studies from South Australia and Queensland indicated the potential of this weed to emerge under a broad range of light and temperature conditions. Darkness inhibited germination compared to an alternating light and dark environment, however 40% germination was still achieved in the dark environments. Annual sowthistle was also shown to germinate under a broad range of soil pH, salinity conditions and water stress environments, although germination was substantially higher under non-water stressed environments where surface soil water was close to saturation.

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Recent studies investigating the effect of seed burial depth and the impact of stubble residue on germination have shown the following results.

Figure 7. Effect of seed burial and residue cover on the emergence pattern of two populations of annual sowthistle sourced from St George and Dalby areas of Queensland (Manalil and Chauhan,

GRDC UA000156)

Salient findings

• Freshly collected seeds readily germinated in water (more than 85%) indicating lack of dormancy in freshly harvested seeds

• Annual sowthistle could germinate under a broad range of temperatures (5/15, 10/20, 15/25 and 20/30 degrees Celsius day/night temperatures), germination was the lowest at 5/15 oC. Notably, germination was more rapid at 15/25 and 20/30 C day/night temperatures than at 10/20 oC. This indicates the adaptability of populations from Queensland to warmer environments

• Continuously dark conditions inhibited germination

• Significant reduction in germination was observed in studies when residue cover was increased to 4000 kg/ha compared to no-residue cover (Figure 7)

• Annual sowthistle germinated over a broad range of soil pH (4 to 10), with a level of germination observed at osmotic potential as high as -8 MPa and at salinity level of 200 Mm

• Seed germination decreased with increasing depths. Zero germination was observed at 4-6 cm depth (Figure 7)

Seed persistence at different depths

In work conducted by Manalil and Chauhan in 2015-17, seed persistence was evaluated for a period of 18 months at 0 cm, 2 cm and 10 cm depths on two populations from St George and Dalby. Seeds were exhumed at different times (0, 3, 6, 12, 18 months after burial) and examined in the laboratory for their germination.

Salient findings

1. At 3 months, there was 62% and 59% lab germination from seeds placed on the surface layer for the Dalby and St George populations, respectively. However, there was a rapid decline in germination from the surface layer over time. At 6 months, germination declined significantly


61 to less than 11% germination from the surface layer. At 18 months, seeds at the surface layer were completely germinated (in the field) or decayed.

2. There was around 80% lab germination from seeds buried at 2 cm depth at 3 months. There was significant reduction in germination at this layer over time. At 12 and 18 months, lab germination at this layer declined to around 30% and 13%, respectively.

3. For seeds that were buried at 10 cm, the pattern of lab germination was similar to the 2 cm depth, although germination was slightly lower than the 2 cm layer. There was around 60% lab germination observed for seeds buried at this layer at 3 months. Germination declined significantly over time with less than 17% and 8% germination at 12 and 18 months, respectively.

Results of burial depth and seed persistence studies indicated the possibility to include tillage (aiming for seed burial) as an option for the management of this weed. This is because there was significant reduction in the level of emergence from seeds buried at layers deeper than 2 cm (less than 25%) and the seed depletion over time as indicated by the seed persistence study. The results justify grower experience of successful management of this weed using tillage.

Competitiveness of annual sowthistle

A study at Gatton Queensland explored the competitiveness of annual sowthistle in an irrigated wheat crop. The density for sowthistle was 0, 13, 36 and 70 plants/m2 for nil, low, medium and high-weed density plots, respectively (Figure 8). The corresponding yield loss was 20%, 50% and 56% at low, medium and high densities of sowthistle, respectively. The analysis indicated that the weed density of 51 plants/m2 annual sowthistle could cause a yield reduction of 50% under the tested environment.

Figure 8. An exponential regression model showing the relationship of wheat yield and weed density (at the anthesis time) of annual sowthistle. The green arrow shows the weed density (plants/m2) to

reduce 50% of the maximum grain yield (Manalil and Chauhan, GRDC UA000156)

Management of annual sowthistle

• Crops vary in their competitive potential to supress annual sowthistle. Barley, with its capacity to generally attain canopy closure earlier than wheat, would supress weeds better than wheat

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• Increasing wheat seeding rate in a good year would assist the crop to out-compete weeds and minimise yield losses from uncontrolled weeds. Similarly, narrow crop rows (e.g. 25 cm for cereals) could suppress annual sowthistle more than a crop sown on 50 cm rows

• Tillage can be used to control the emerging weeds and bury the seeds. It is always advisable to allow the seeds on surface to emerge before tillage as that would deplete a substantial portion of seeds in the soil surface

• Weed blowouts in fallows often follow weeds that survive control in winter crops. For this reason, sound management and control strategies in winter crops is a critical control strategy

• Weed management in fallow is also very important, as this weed can establish in spring by exploiting the nutrients and resources of the winter crop and use fallow as a breeding place (Figure 9)

Figure 9. Annual sowthistle establishment in a fallow at Gatton (photograph taken

by B. Chauhan on 27th August 2017).

Weed control options

Annual sowthistle has already evolved resistance to glyphosate (Group M), chlorsulfuron (Group B), and 2,4-D (Group I) in Australia. This necessitates implementing a diverse approach to the management of this weed species. Growers are recommended to implement a range of strategies as identified in the WeedSmart “The Big 6” https://weedsmart.org.au/the-big-6/

1. Rotate crops and pasture

2. Double knock

3. Mix and rotate herbicides

4. Stop weed seed set

5. Crop competition

6. Harvest weed seed control

Herbicide options

A range of products are available for the control of annual sowthistle but care should be taken to maximise and preserve their efficacy. All products should be applied at the correct growth stage, increasing application water volume as plants size increases and avoiding spraying weeds during period of acute water and heat stress. Herbicide options for the control of sowthistle include:

https://weedsmart.org.au/the-big-6/


63 1. In fallow situations apply Group M (glyphosate), Group L (paraquat, diquat), Group N

(glufosinate), Group G, and Group Q (Amitrole) herbicides, standalone or in mixtures as per label directions.

A double knock approach may help to minimise the impact annual sowthistle has in the fallow. Ensure glyphosate standalone or in mixtures is followed by Spray.Seed®, paraquat or other suitable 2nd knock herbicides such as Group G (saflufenacil).

Using camera sprayer technology in fallows with labelled or permitted herbicides may also allow for the precision application of herbicides so the costs of fallow management can be minimised.

2. Pre-emergent herbicide options can be used prior to the planting including Group C, Group G (flumioxazin) and Group H (isoflutole) herbicides providing residual control of emerging sow thistle plants as per label directions.

3. Use of registered products containing herbicide Groups C, F, H and I herbicides can be useful to help manage weeds in crop prior to weed seed set as per label directions.

4. At crop maturity, use of herbicides in Groups M, L and G (saflufenacil) can be used in various crops as desiccants or spray topping of late weeds as per label directions.

Note: All products must be applied in accordance with label “Directions for Use” as published by the APVMA https://productsearch.apvma.gov.au/products.

Sources

Chauhan B.S., Gill G. and Preston C. 2006. Factors affecting seed germination of annual sowthistle (Sonchus oleraceus L.) in southern Australia. Weed Science 54: 854-860.

Online resource DAF Queensland. Preventing herbicide resistance in 'at risk' weeds. Accessed on 26/8/2017.

Online resource GRDC. Integrated weed management in Australian cropping system. (Accessed on 25/8/17. www.grdc.com.au/IWMM

On line resource. Department of Agriculture, Queensland. Management of common sowthistle (fact sheet). Contributors: Michael Widderick and Steve Walker.

Online resource. Northern IWM factsheet. Common sowthistle, Sonchus oleraceous L. Ecology and Management. Contributors: Chauhan B.S. Widderick, M, Werth J, Cook T. Department of Agriculture and Fisheries, Queensland, (2015).

Acknowledgements

The research undertaken as part of this project is made possible by the significant contributions of growers and agronomists through both trial cooperation and the support of the GRDC, Queensland Government, Charles Sturt University and The University of Sydney. The author would like to thank them for their continued support.

Contact details

Paul McIntosh Australian Herbicide Resistance Initiative Address: 7 Berghofer Drive, Highfields Qld 4352 Mb: 0429 566 198 Email: [email protected]


https://productsearch.apvma.gov.au/products

https://www.daf.qld.gov.au/business-priorities/plants/field-crops-and-pastures/broadacre-field-crops/weed-management-in-field-crops/herbicide-resistance/preventing-herbicide-resistance-in-at-risk-weeds

https://grdc.com.au/resources-and-publications/all-publications/publications/2014/07/iwmm

http://www.grdc.com.au/IWMM

https://www.daf.qld.gov.au/business-priorities/plants/field-crops-and-pastures/broadacre-field-crops/weed-management-in-field-crops/sowthistle

https://www.daf.qld.gov.au/business-priorities/plants/field-crops-and-pastures/broadacre-field-crops/weed-management-in-field-crops/sowthistle

https://qaafi.uq.edu.au/files/5955/Common-Sowthistle-%28Sonchus-oleraceus-L_%29-ecology-and-management.pdf

https://qaafi.uq.edu.au/files/5955/Common-Sowthistle-%28Sonchus-oleraceus-L_%29-ecology-and-management.pdf

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Nitrogen management. A seasonal journey with many routes and destinations

Chris Dowling, Back Paddock Co.

Key words

volatilisation, ammonia, urea CEC, nitrogen, movement, pools, efficiency, budget

Take home message

With the decline in native soil N fertility the once smoother road of seasonal nitrogen (N) management has now become a bumpy “goat track”. Strategic and tactical fertiliser decisions are more critical than ever in ensuring every drop of crop available water counts.

Ammonia volatilisation from surface spread urea

• Ammonia volatilisation from surface spread ammonium forming fertiliser such as urea, ammonium sulphate and ammonium phosphates is a natural soil process occurring in pristine natural environments from animal urine patches. The real discussion in cropping and pastures is about the cumulative loss and its cost, and the trigger point for losses to necessitate product or practice change

• In our high clay content soils, ability to trap ammonia (NH3) as it is created during the breakdown of urea (via soil CEC) is more important than soil pH

• Ammonia volatilisation losses in high clay content soil may be significantly less than first thought

Vertical nitrogen movement in the soil during fallow

• Using single factor old “rules of thumb” that relate soil wetting depth to subsequent nitrate-N movement down the profile, clearly over- estimate N movement in clay soils and in order to be more realistic, need to be recalibrated to include consideration of the starting soil water distribution, time of year and post application rainfall patterns

• Outputs of soil moisture accumulation modelling tools (Soil Water App, CliMate) are likely to be more realistic than old “rules of thumb” and possibly good tools to develop new N movement perspectives.

N Budgets or N Fudgets?

• Changes in soil N supply, farming practice and fertiliser technology suggests outputs from traditional N budgets may be insensitive to changes such as reduced lower native soil N fertility, higher frequency of pulses, ley cropping and differences in fertiliser uptake efficiency

• Reduction in availability of native N and increased N from legume rotations and/or stored mineral N, makes fertiliser N management more critical than in the past due to the loss of seasonal “buffering” these sources of N provided

• 1 kg residual soil mineral N located between 10 and 60 cm in the soil profile and N mineralised in crop may be 1.5 – 3 x as effective 1 kg N as fertiliser N in the year it is applied.

Ammonia volatilisation losses from surface applied urea and ammonium fertilisers

Nitrogen (N) fertiliser inefficiency driven by accelerated ammonia volatilisation is real. The appropriate discussion is probably about risk, likely amount, and trigger point for losses to necessitate product or practice change.


65 Prior to recent work by Graham Schwenke (Schwenke 2014), our knowledge of process and risk of ammonia volatilisation in vertosols was influenced by work in soils and conditions unlike those that exist in the northern grains region. Putting it simply, from local vertosol based research it now appears in these high clay content soils, their ability to trap the ammonia created during the breakdown of urea, is more important than soil pH in determining the amount of ammonia volatilised. Losses measured from research in lower clay content soils and climatic areas, indicates a dominance of soil pH in the ammonia volatilisation process. Graeme Schwenke’s research showed that in many circumstances ammonia volatilisation losses are significantly less than first thought in our high clay content vertosols.

Table 1. Key factors controlling ammonia volatilisation rate and total N loss from urea application. Factors Effect Soil cation exchange capacity Higher CEC = higher ammonia adsorption rate and

adsorption capacity = lower loss rate Soil pH Higher pH = more rapid rate Micro- meteorological conditions Higher temperature and wind speed = increased loss rate Granule location Higher soil contact/cover = lower loss rate Granule wetting Incomplete wetting = increased loss Time Increased time in unfavourable conditions = greater total

loss

Because future weather conditions (particularly rainfall and wind) are significant factors in the loss process, predicting absolute loss accurately is not possible. Gaining a perspective of the relative loss and costs of various application tactics is useful in making the trade-off between obtaining highest N efficiency and N application logistics (time, coverage of area, soil moisture loss, available labour and equipment etc). The model suggested by Fillery and Khimashia 2016 provides a useful approach to compared potential loss from differ N application strategies.

Figure 1. An example of an ammonia volatilisation scenario comparison. Broadcast and incorporated

vs broadcast only, no rain 14 days. Calculator (based on Fillery and Khimashia 2016).

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How fast does nitrogen move in the profile in vertosol and scrub soils?

Whether it be urban real-estate, farm location, or nutrient distribution in soil, ‘location, location, location’ is a key to success. This has been demonstrated for P and K in CQ, but the same principles apply for N, particularly where the crop is highly dependent on fertiliser N derived from a single application. The difference between the P, K and N, is that N (when in the urea, nitrite and nitrate forms) is a mobile nutrient - meaning that it doesn’t necessarily need to be placed at a particular location. Soil water movement can be used to help achieve an appropriate soil N distribution from a range of application methods.

The distribution of nutrients relative to root density and soil available moisture is the main game for efficient uptake. How you get there is somewhat dependent on rainfall, but there are some key factors that need to be considered in providing some possibility to getting targeted soil N distribution.

Key factors in determining appropriate soil N distribution include

• Current soil N distribution

• Current quantity and distribution of soil water

• Critical crop N stages

• Crop root structure

• Soil profile physical, chemical and biological characteristics

Figure 2. Generalised soil root distribution for cereal crops at maturity

Efficient nutrient uptake is achieved by having the appropriate concentration in a soil layer, co-located with crop available water and high root density.

The rate of soil water movement in cracking clay soil can be difficult to predict, being affected by factors such as cracking and swelling, and their interaction with rainfall patterns.

Irrespective of a soil type, once N is in the nitrate (NO3-) form it is mobile in the soil, moving laterally

and horizontally with water movement.

Probably the scenario most reliably predicted is when N applied to a full moisture profile is unlikely to move far due to restricting internal water flow due to the lack of cracks (preferential flow) and soil swelling (effect on soil water potential and capillary rise). However, applying fertiliser N to a dry profile does not necessarily guarantee well distributed N due to its reliance on interactions with rainfall patterns.

Recent research reported by Richard Daniel for southern Queensland and northern NSW (Daniel et al. 2018) suggests that nitrate - N movement down the profile during a summer fallow as it fills may


67 not be as great as generally expected when considering the total rainfall received and applying old “rules of thumb” (Figure 3).

Figure 3. Soil distribution of N at Tulloona at planting (June 2016) following application of urea in

December 2015 or February 2016. (Daniel et al 2018).

It becomes clearer when looking at rainfall and evaporation patterns that the amount and timing of rainfall (Figure 4) would be unlikely to provide sufficient excess soil water in surface layers to create significant percolation of water and nitrate-N deeper into the soil.

The rate of conversion of urea to nitrate-N in the initial 30 days after application may have also impacted these results and explain the lack of movement resulting from the 4 days of rain in early January 2016. If the majority of the N in was still ammonium, movement in soil water would be minimal.

Figure 4. Seasonal rainfall and ET at Tulloona (BOM Coolanga) for the period

December 2015 to June 2016.

Using single factor old “rules of thumb” that relate soil wetting depth and subsequent nitrate-N movement down the profile clearly over- estimate N movement in clay soils and in order to be more realistic, need to be recalibrated to include consideration of the starting soil water distribution, time of year and post application rainfall patterns. Outputs of soil moisture accumulation modelling tools (Soil Water App, CliMate) are likely to be more realistic than old “rules of thumb” and are possibly good tools to develop new N movement perspectives.

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N Budget or N Fudget?

A brief history of the N budget

As a result of the big dry in the early mid 1990s it was felt that the old system for determining N requirement (largely hard copy single dimension lookup tables – CFL Soil Test Interpretation Manual) needed improvement. To cope with yield and protein dynamics and variable soil mineral N status post drought, an N education program (Nitrogen in 95) was developed by then QDPI and CFL. The training process subsequently morphed into what we now know as the ‘N Budget’. Given that more than 20 years have passed since the original budget calculations were developed, it is not unexpected that “cracks” are appearing and new scenarios are appearing that are not catered for in the original N Budget.

So what’s changed in that time that may affect N budgets I here you ask? The following is a list of candidate issues:

• Fallow practices (reduced soil disturbance frequency and intensity = decreased mineralisation)

• Older soils with lower OC % (Figure 5)(reduction in native organic N = decreased mineralisation) (Bell et al. 2010)

• Increased fallow efficiency (increased yield potential = increased N demand)

• Change in grain marketing (downward trend in wheat quality premiums = lower N demand)

• Increase in non-cereal crops in the rotation (increase labile N = short term seasonal boost N supply and uptake efficiency = decrease in the need for fertiliser N)

• More volatility in grain price/N cost ratio (increase volatility = multiple yield scenario approach)

• Availability of proximal and remote sensing to judge crop performance and spatial variability (in crop performance date = ability detect and act on unplanned scenarios)

• Wider range of N application equipment and product options (more in-crop application options = ability to implement fertiliser scenarios with higher NfUE.)

• Greater validation of finer detail of workings of parts of N cycle in vertosols of the north (flexibility = ability to create more realistic scenarios).

Figure 5. As the contribution from organic matter derived nitrogen declines (OC %), the dependence on other seasonal N sources increases. The rate of replacement N required depends on strategies

and tactics employed by managers to supplement the main supply pools.


69 An N budget tries to define the status of a range of soil N supply pools at a point in time and its ability to supply crop demand for a likely yield range. The accuracy of the prediction of N requirement is dependent on 4 main factors:

• The size of the N pool

• The efficiency of uptake from the pools

• Soil water availability to match N availability

• Ability to supplement the deficit with effective fertiliser tactics.

Table 2. General range of short term crop uptake efficiency of N from four major supply pools by cereals.

Major Soil N Supply Pool (and crude working definition) General Crop Uptake Efficiency in Cereals1

Humic OM - contributed after more than 3 seasons of mineralisation 70 – 90 %

Labile OM - contributed from crop residues with less than 3 seasons of mineralisation

70 – 90 %

Soil profile mineral N - nitrate and ammonium below 10 cm at sowing 50 – 70 %

High concentration, rapidly mineralisable fertiliser N - applied in fallow,

- applied in crop

10 – 40 %

20 – 60 % 1. Does not include any significant seasonal episodic loss event.

Crop N supply pools are not all the same, differing in both quantity of N supplied and efficiency of crop uptake (Table 2). Significant changes in the N supply pool balance and crop N uptake efficiency each can have a profound effect on crop N supply and seasonal fertiliser N requirement.

References

Richard Daniel, Rachel Norton, Anthony Mitchell, Linda Bailey, Denielle Kilby and Branko Duric (2018) Nitrogen Use (In) Efficiency In Wheat – Key Messages From 2014-2017, GRDC Update Paper. [accessed: https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/03/nitrogen-use-n-efficiency-in-wheat, 17/10/2018].

Ian R. P. Fillery and Nirav Khimashia (2015) Procedure to estimate ammonia loss after N fertiliser application to moist soil. Soil Research 54(1) 1-10.

Graham Schwenke (2014) Nitrogen volatilisation: Factors affecting how much N is lost and how much is left over time. GRDC Update Paper, [accessed: https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2014/07/factors-affecting-how-much-n-is-lost-and-how-much-is-left-over-time, 17/10/2018].

Mike Bell, Phil Moody, Kaara Klepper and Dave Lawrence (2010) Native soil N decline. The challenge to sustainability of broadacre grain cropping systems on clay soils in northern Australia, 9th World Congress of Soil Science, Soil Solutions for a Changing World, 1 – 6 August 2010, Brisbane, Australia.

Contact details

Chris Dowling Back Paddock Company Unit 1 / 13-15 Steel St, Capalaba, QLD 4157 Ph: 0407 692 251 Email: [email protected]

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Getting nutrition right in Central Queensland Doug Sands1, Mike Bell2 and David Lester3

1 Queensland Department of Agriculture and Fisheries, Emerald 2 Queensland Department of Agriculture and Fisheries, Gatton 3 Queensland Department of Agriculture and Fisheries, Toowoomba

Key words

nutrition, Central Queensland, phosphorus, potassium, nitrogen, soil testing, deep banding

GRDC code

UQ00063 Regional soil testing guidelines

Take home message

• Soil testing in the correct depth increments is important in order to separate the surface (0-10cm) and sub-surface (10-30cm) nutrient status in order to identify the magnitude of nutrient stratification. This will determine yield response to deep applied nutrients.

• Yield responses to deep applied phosphorus (P) in Central Queensland (CQ) have ranged between an extra 14-100% of the treatment with no deep P

• Yield responses to deep applied potassium (K) in Central Queensland (CQ) have ranged from an extra 8-29% of the treatment with no deep K

• Responses to deep banding P and K in the sub-surface layer can be influenced by; (1) nutrient status of surface layers, (2) in-crop rainfall, (3) crop species, (4) nitrogen status

Introduction

Over the past five years the UQ00063 project has been monitoring a series of nutrition-based trials sites across Central Queensland (CQ). These trial sites were chosen based on soil test evidence showing varying degrees of nutrient depletion in the surface (0-10cm) and sub-surface (10-30cm) layers.

This is particularly evident for the non-mobile nutrients of phosphorus (P) and potassium (K). In some established zero tillage production systems there is a marked difference between the nutrient concentration in the top 10 cm of the soil profile and the deeper layers (10-30 cm and 30-60 cm) that cannot be explained by natural stratification. It would seem that this pattern of soil analysis is becoming more evident across CQ, particularly in the Brigalow scrub and open downs soil types.

This project aims to find whether a one-off application of P and/or K, placed in the sub-surface layer (10-30cm) can provide a grain yield benefit and whether that benefit can be maintained over several years.

Experimental outline

Eight trial sites were initially established with deep P trials, and six of those sites also had deep K trials co-located in the same field (i.e. both P and K were marginal to low). All trials followed a similar protocol with eight common treatments. The four main treatments were based around increasing rates of P or K. For the P trials; rates of 0, 10, 20 and 40 kg of P/ha were used. The K trials included 0, 25, 50 and 100 kg of K/ha. In all treatments, background fertiliser was applied to negate any other potentially limiting nutrients. This background fertiliser included; 80 kg of nitrogen (N), 50 kg of K (if it was a P trial), 20 kg of P (if it was a K trial), 20 kg of sulfur (S) and 1 kg of zinc (Zn).


71 These main rate treatments were accompanied by two other treatments that included the highest and lowest rate of nutrient without the background P or K (i.e. P trials had no background K or S, and vice versa), although background N and Zn were retained. These allowed us to assess the interacting effects of P or K if the other nutrient was also limiting (e.g. would we see a K response if we did not first fix low P). A final two treatments included farmer reference (FR) plots, and an extra zero plot to give two controls for each replicate. The FR treatments had nothing additional applied during the initial application of treatments and were not deep ripped, thus representing normal commercial practice of the current farming management (Table 1 and Table 2).

Treatments were applied using a fixed tine implement that delivered the P and K bands at a depth of 20 cm and the Nitrogen (N) and Sulphur (S) bands at a depth of 10–15 cm. The bands of fertiliser were placed 50 cm apart in plots that were six to eight meters wide and 28-32 m long. The bands of fertiliser were placed in the same direction as the old stubble rows. Most trials had six replicates. Commercially available fertiliser products were used in all treatments (Table 3).

On some sites the effects of an additional starter fertiliser treatment applied at planting were also evaluated, with the main plots split into ‘with’ and ‘without’ starter. Starter fertilizer was applied at a general rate of ~30 kg/ha, either as MAP or Starter Z.

Table 1. Summary of nutrient application rates for P trials

Main treatment label

Starter treatment label

N rate (kg/ha)

Starter P rate (kg/ha)

P rate (kg/ha)

K rate (kg/ha)

S rate (kg/ha)

Zn rate (kg/ha)

0P Nil starter 80 0 0 50 20 1

0P Starter 80 1.5 0 50 20 1

10P Nil starter 80 0 10 50 20 1

10P Starter 80 1.5 10 50 20 1

20P Nil starter 80 0 20 50 20 1

20P Starter 80 1.5 20 50 20 1

40P Nil starter 80 0 40 50 20 1

40P Starter 80 1.5 40 50 20 1

40P-KS Nil starter 80 0 40 0 0 1

40P-KS Starter 80 1.5 40 0 0 1

0P -KS Nil starter 80 0 0 0 0 1

0P -KS Starter 80 1.5 0 0 0 1

FR Nil starter 0 0 0 0 0 0

FR Starter 0 1.5 0 0 0 0

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Table 2. Summary of nutrient application rates for K trials.

Main treatment label

N rate (kg/ha)

P rate (kg/ha)

K rate (kg/ha)

S rate (kg/ha)

Zn rate (kg/ha)

0K 80 20 0 20 1

0K 80 20 0 20 1

25K 80 20 25 20 1

50K 80 20 50 20 1

100K 80 20 100 20 1

0K-PS 80 0 0 0 1

100K-PS 80 0 100 0 1

FR 0 0 0 0 0

Table 3. List of commercial granular products used in nutrient treatments

Nutrient Product source of nutrient in applications

Nitrogen (N) Urea (46%), MAP (10%), GranAm® (20%)

Phosphorus (P) MAP (22%)

Potassium (K) Muriate of Potash (50%)

Sulphur (S) GranAm (24%)

Zinc (Zn) Agrichem® Supa ZincTM (Liq) (7.5%w/v)

Results

From the eight trial sites established with this methodology, six proved to be responsive to deep P application. Of the six deep K trials that were co-located with the P trials, four proved to be responsive. The size of the responses to both deep P and K have been variable across seasons and crop species.

There have been 13 crops grown across the six responsive deep P sites and nine of these have shown significant differences at the P<0.001 level (Table 4). For the responsive K trials there have been nine crops grown of which seven have shown significant differences.


73 Table 4. Summary of significant site responses to deep P and K across crops and seasons. Maximum

yield response achieved (as a % of the ‘0P’ or ‘0K’ treatments) Site Year Crop Significance

level of response to deep P

Max. yield response to deep P (% of ‘0P’ mean)

Significance level of response to deep K

Max. yield response to deep K (% of ‘0K’ mean)

Dysart 2014 Sorghum P<0.001 22.2 P<0.001 7.8 2015 Sorghum P<0.001 15.2 P<0.001 9.5 2016 Sorghum P<0.001 15.3 n.s. - 2017 Chickpeas P<0.001 99.6 P<0.001 28.8 Springsure Creek

2014 Sorghum P<0.001 23.8 n.s. -

2016 Sorghum n.s. - n.s. - Comet River 2016 Chickpeas P<0.001 24.2 n.s. - 2017 Wheat n.s. - n.s. - Clermont 2016 Sorghum P<0.001 39.1 P<0.001 11 Kilcummin 2015 Chickpeas P<0.001 30 P<0.001 9.4 Dululu 2016 Wheat n.s. - n.s. - 2017 Chickpeas P<0.001 13.8 P<0.001 16 2018 Mungbeans n.s. - P<0.001 15.8

Responses to deep banded P have in general been, consistent with soil test values (Table 5), with large grain yield responses of between 14% and 100% recorded (Table 4).

The K responses have been smaller, with yield responses ranging from 8% to 29% and these responses have not always followed the predicted response based on soil test values (Table 5). For example, the Comet River site has a low exchangeable K reading in the sub-surface layer (10-30cm) but so far has not responded to deep K in chickpeas or wheat, while the Clermont site had a higher exchangeable K status in the same layer but did respond to deep K in sorghum. At least part of the reason for the uncertainty around K responsiveness relates to seasonal conditions and the amount of K that can be utilised out of the topsoil when it is wet enough. It also reflects that the soils are not as depleted in K as they are in P at this stage of the crop cycle. There may also be slow release K minerals present at some sites which the exchangeable K test does not measure.

Table 5. Soil test values for P and K at all responsive trial sites. Site Names Colwell P (mg/kg) BSES P (mg/kg) Exchangeable K

(meq/100g) 0-10cm 10-30cm 0-10cm 10-30cm 0-10cm 10-30cm

Kilcummin 6 <2 13 7 0.65 0.25 Dysart 5 <2 8 3 0.25 0.12 Clermont 5 2 38 26 0.48 0.22 Dululu 17 3 20 4 0.22 0.12 Springsure Creek

12 4 30 6 0.31 0.09

Comet River 22 5 24 5 0.46 0.12

When assessing soil test results to identify possible nutrient constraints, the following tables (Table 6 and Table 7) are a useful guide. These figures are based on extrapolation of trial data that has been accumulated across all Queensland nutrition sites over the last five years. It is also worth noting that

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the critical values for K may increase somewhat in soils with a high cation exchange capacity (i.e. >40 cmol/kg)

Table 6. Current recommendations for assessing soil P status from soil test analysis

Phosphorus Low Moderate High

Colwell P 0-10 cm seeding P < 8-10 15 >25

10-30 cm <7 8-12 >15

Phosphorus Buffer Index (PBI) (low is better)

<150 150-300 >300

BSES P (subsoil P)

<40 40-150 >300-400

Responsive Use test strip Subsoil reserves OK

Table 7. Current recommendations for assessing soil K status from soil test analysis

Exchangeable K (meq/100g)

Low Moderate High

0-10 cm <0.2 0.2-0.3 >0.4

10-30 cm <0.15 0.15-0.2 >0.2

To convert meq/100g or cmol/kg to mg/kg (ppm) multiply by 390

Interactions with deep P and K responses

Consistency in response to deep P and K is dependent on a number of factors. Some of these factors relate to the concept of nutrient stratification, which is driven by the lack of mobility of both these nutrients in our clay soils. Stratification occurs when there is a build-up of P and K in the surface layers from either starter fertiliser application (P) or the constant breakdown and release of nutrients including P and K out of stubble. While enrichment of the surface layers by these two processes is occurring, there is a depletion of these non-mobile nutrients out of the sub-surface layers from normal plant uptake, particularly during dry seasons. When roots are living on stored soil moisture, they are also accessing subsoil nutrients to be able to grow successfully.

A number of the P responsive sites in CQ have adequate levels of P in the surface layer (0-10cm) but that P status drops off significantly in the sub-surface layer (Dululu, Springsure Creek and Comet River). This characteristic can affect the seasonal response to deep placement of nutrients. When adequate in-crop rainfall is received then the surface layers hold moisture and allow the plant to access those surface nutrients. This reduces the reliance of the plant on being able to forage for water and nutrients deeper in the profile.

When the crop has little in-crop rainfall, which is quite common in CQ winter crops, the surface layer dries out and the plant is unable to access those non-mobile nutrients trapped in the dry surface soil. This is why quite often the strongest response to deep banded P and K is in dry seasonal conditions.

Timing of rainfall in relation to crop stage can also have an influence on response to deep P and K. Different crop species set components of yield at different stages in the crop cycle. For example, grain number in wheat is set during the first six weeks after planting, and the number of tillers (and hence grain heads/ha) are determined shortly thereafter, so this is a critical period for crop P availability. Conversely, a crop like chickpeas sets its yield from the start of flowering (60 days after sowing) and the next 30 days following – considerably later in the season. If surface soils are dry


75 during these critical periods, the plant has to access nutrients in the sub-surface layers, and it is in those seasons when deep placement of P and K have the largest impact.

This concept is best exemplified by data collected at the Dululu site, where there was no significant response from the deep placed nutrient treatments in wheat in 2016 but there was a significant response to both P and K in the chickpea crop in 2017 (Table 4). Rainfall data (Figure 1) would suggest the chickpea crop experienced a very dry surface soil profile at the start of flowering and over the following 40 days, meaning reliance on deeper soil layers for P and K was likely to be high. In contrast, the previous wheat crop had a number of significant in-crop rainfall events that would have ensured that the crop had access to surface soil nutrients in moist soil for extended periods during the season.

Figure 1. Comparison of accumulated in-crop rainfall for the 2016 and 2017 seasons at the Dululu

site. Wheat grown at the site in 2016 and chickpeas grown in 2017.

Another plant characteristic that would have influenced the result at the Dululu site would be root structure. Cereal crops such as wheat have an adventitious root system, which has a high proportion of fine roots (high surface area for absorption) and generally a large root mass spread throughout the profile (like a spider web). This makes wheat a very good forager for nutrients, as it has more opportunities to exploit more of the soil containing non-mobile nutrients. Therefore, in soils with constrained P and K levels, wheat has an advantage with its root system in that it can minimise the impact of low nutrient status better than a chickpea crop can.

In contrast, grain legumes such as chickpeas tend to have a tap root system with fine lateral roots developing from the main tap root. This means generally a lower total root mass and a lower total surface area for the root system, so a root system that is potentially less able to exploit a given soil volume. Grain legumes tend to overcome this constraint by being very dependent on symbiotic relationships with organisms like mycorrhizae (VAM) to assist in acquiring nutrients.

There is no doubt that based on the trial data collected over the last 5 years, chickpeas have had a much stronger response to deep applied P and K than sorghum or wheat in the CQ region. While

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grain legumes such as chickpeas do have higher grain nutrient concentrations, cereals are also vulnerable to low soil nitrogen availability – something that does not typically impact on grain legumes. General soil test values across a number of CQ sites have suggested that low N status may be limiting cereal crop yields in a number of paddocks (Figure 2).

Figure 2. Summary of starting nitrates across several CQ sites.

This has led to low protein levels (7-8% in sorghum and wheat) in some trials where the responses to P and K have been limited. Chickpea crops grown after cereal crops have shown much larger responses to the deep P and K than in the previous cereal crop. Part of this response is thought to be because there is no N limitation for a grain legume. Data collected from the Dysart site has shown good evidence of this issue (Figure 3).

Figure 3. Yield response to deep P over 5 consecutive crops in relation to zero P treatment

at Dysart trial site.


77 The difference between the 2015-16 sorghum and the 2017 chickpea crop (Figure 3) in terms of relative yields is dramatic (15% to 100%). It is possible that some of this yield increase may be due to chickpeas being not limited by nitrogen levels where as the sorghum crops can be.

The 2018 sorghum crop following on from the 2017 chickpea crop has achieved the highest relative yields of all the sorghum crops grown at this site since the initial application of deep P and K treatments. The main difference between the 2018 sorghum and the previous three sorghum crops has been a doubling of the urea application in the fallow prior to planting. The first three sorghum crops received 100 kg/ha of urea whereas the 2018 crop received 200 kg/ha. While protein analysis is yet to be completed for the 2018 sorghum crop, the difference in yields alone from crop to crop are strong evidence of the importance of N status in realising the full yield benefit from P and K application in cereal crops.

Summary

In general, soil test values have predicted responses to deep placed P and K in 80% of sites tested in CQ using depth increments that ensure separation of the surface and sub-surface layers. While the scale of these responses has been variable, the P response have been reliable.

There are a number of factors that will influence the size of the response from deep placed P and/or K. These factors include:

• Concentration of nutrient in the top 10cm

• Amount and timing of in-crop rainfall

• Crop species

• Nitrogen status

Acknowledgements


Contact details

Doug Sands Department of Agriculture and Fisheries LMB 6, Emerald QLD 4720 Ph: 07 4991 0811 Email: [email protected]

® Registered trademark ™ Trademark

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Central Queensland Grower Solutions Managing subsoil nutrition – grower experience, Lee Jones

Compiled by: Hayley Eames, DAF Qld.

Key words

Case study, nutrition, subsoil, central Queensland, CQGS, trials, Lee Jones

GRDC code

DAQ00205

Take home message

My advice would be to just give it a go.

If you suspect that you might have a problem, I would recommend getting some detailed soil tests done at depth and then put down some strip trials with your own planter.

Get a couple of one tonne bags, mark out and then monitor your strips - this will soon give you an indication as to whether you are likely to get a response.

Grower

Lee Jones, Rolleston, Qld.

Figure 1. Lee Jones

Farming area

3500 hectares

What did your previous fertiliser program involve?

60-80kg/ha urea applied pre-plant


79 What was the driver for undertaking a subsoil nutrition program?

Soil tests showed that phosphorus levels were very low in both the topsoil and subsoil layers with Colwell P values of 3 mg/kg and 1 mg/kg respectively.

How did you go about implementing your subsoil nutrition program?

• Depth: 20cm

• Row Spacing: 40cm

Rates

A strip trial was conducted with three different treatments:

• Control = no fertiliser applied, planter pulled through strip at same depth as deep applied treatments

• 120kg/ha MAP + 60kg/ha Urea ($119/ha)

• 240kg/ha MAP + 120kg/ha Urea ($238/ha)

Equipment

We used a 15 metre Gyral Sure Strike Tyne Planter. No major modifications were required; however, we did raise the coulter and press wheel heights and increased the down pressure on each unit to help keep the planter at depth.

Horsepower wasn’t a problem as we used a John Deere 8360 tractor (360hp capacity). However, we did have to reduce travel speed down to 7km/hr. Fuel use was around 55L/ha compared to 35L/ha under standard operations.

Figure 2. Gyral Sure Strike planter

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What results have you observed?

Table 1. Yield results from the 2017 wheat crop comparing nil treatment and deep applied fertiliser Wheat 2017

Nil 180kg/ha (120kg/ha MAP +

60kg/ha Urea)

360kg/ha (240kg/ha MAP + 120kg/ha Urea)

Yield (t/ha) 1.8 2.1 2.2 Yield increase +21% +29%

Payback period?

We estimate that we have already recouped 2/3 of the application cost back in our first wheat crop and anticipate a stronger response in the following legume crop. We expect the payback period to be close to 2 years.

Were there any challenges associated with implementing a subsoil fertiliser program?

Getting the timing of application right in order to minimise soil disturbance is critical. When we applied in February 2017 the soil was still quite moist and as such we were continually bringing up large clods of soil, which can present problems when it comes time to plant.

Where to next?

Our plan for the next 3-5 years is to continue to monitor the current site for protein and yield as well as undertake regular soil testing. This should give us a better understanding of what the site can produce overtime as well as the potential longevity of response.

What advice would you have for other growers looking at implementing a subsoil fertiliser program?

My advice would be to just give it a go. If you suspect that you might have a problem, I would recommend getting some detailed soil tests done at depth and then put down some strip trials with your own planter. Get a couple of one tonne bags, mark out and then monitor your strips - this will soon give you an indication as to whether you are likely to get a response.

Contact details

Hayley Eames DAF Qld, Biloela Ph: 07 4808 6815 Mb: 0459 813 389 Email: [email protected]

Lee Jones Mb: 0429 864 594 Email: [email protected]


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Central Queensland Grower Solutions Managing subsoil nutrition – grower experience, James Olsson

Compiled by: Hayley Eames, DAF Qld.

Key words

Case study, nutrition, subsoil, central Queensland, CQGS, trials, James Olsson

GRDC code

DAQ00205

Take home message Don’t be afraid to do some trials of your own. You don’t need flash gear, a few modifications to your existing equipment and you can generally get the job done.

Grower

James Olsson, Wowan QLD

Figure 1. James Olsson

Farming area

600 hectares

What did your previous fertiliser program involve?

Starter fertiliser (Granulock® Z) at a rate of 25-40 kg/ha and then side dress urea.

What was the driver for undertaking a subsoil nutrition program?

We had a very reliable paddock that consistently out yielded the rest of our cropping country year in year out. Over a period of about three years under a mungbean/wheat rotation, we really noticed that our mungbean crops were suffering and starting to show visual deficiency symptoms.

Initially we tried applying potash at planting, however as the surface dried out and the crop started looking for moisture, we found the deficiency symptoms returned. This was the first indication that potentially the issue was lack of nutrient at depth.

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How did you go about implementing your subsoil nutrition program?

• Depth: 15cm

• Row spacing: 48cm

• Timing: March/April 2015 prior to wheat

Rate

Applied Crop King 66S at a rate of 100kg/ha across one paddock. (13 kg N; 10.6kg P; 15kg K; 4.9kg S)

Equipment

Modified an Orion Centurion chisel plough:

• Initially a 27 tyne machine, have reduced that down to 18 tynes

• Extended the frame from 7.6m to 9m to suit controlled traffic layout

• Equipped with 1,100lbs breakout pressure

• Added hydraulic ram to the front bar to help maintain depth over the contour banks.

We use a John Deere 8760 tractor (300hp) to pull the planter. When it was a 27 tyne machine we required duals to pull it, however modifying it to 18 tynes has meant we have reduced the horsepower requirements and can now use water loaded singles that line up with our controlled traffic configuration.

Figure 2. Modified planter

What results have you observed?

Table 1. Yield results from 2015 and 2016 crops comparing nil treatment and deep applied 100kg/ha of Crop King 66S (13 kg N; 10.6kg P; 15kg K; 4.9kg S).

Both treatments had starter fertiliser of Granulock Z at a rate of 25kg/ha

Wheat 2015 Mungbean 2016

Nil 100kg/ha Nil 100kg/ha

Yield (t/ha) 2.2 3.2 0.5 1

Yield increase +44% +50%


83 Payback period?

We have recouped the cost of application over two crops (wheat & mungbean). The initial fertiliser cost was $80/ha. Based on the 0.5t/ha yield increase at $1000/tonne, we have increased our profitability by $500/ha in our 2016 mungbean crop alone.

Were there any challenges associated with implementing a subsoil fertiliser program?

Getting the timing of application right was our biggest challenge. It was a balancing act between fitting it in with our other business operations and completing it when soil moisture conditions were favourable.

Where to next?

We plan to apply a base rate of N, P, K at depth across all of our cultivation country. As mungbeans are such a big part of our rotation and being such a fast-growing crop, they really can’t afford any setbacks in terms of nutrition.

From there we will continue to monitor levels of nutrient removal through regular soil testing and reassess whether additional deep applications are required in 4-5 years’ time.

What advice would you have for other growers looking at implementing a subsoil fertiliser program?

If you think you are suffering a bit of a nutrient deficiency, get on top of it straight away. We’ve seen a gradual yield decline over the past 8 to 10 years and you can’t sustain or afford inefficiencies in your business in the long term.

Get a comprehensive soil analysis done at depth to accurately determine whether a nutrient deficiency is present.

Finally; don’t be afraid to do some trials of your own. You don’t need flash gear, a few modifications to your existing equipment and you can generally get the job done.

Contact details

Hayley Eames DAF Qld, Biloela Ph: 07 4808 6815 Mb: 0459 813 389 Email: [email protected]

James Olsson Mb: 0488 762 944 Email: [email protected]


Documents

BILOELA GRAINS RESEARCH UPDATE - Home - GRDC · 2018. 12. 6. · Getting crop nutrition right in CQ. Panel session on deep P, K & N. Doug Sands, DAF Qld., Chris Dowling, Back Paddock