www.msfp.org.au
Karoonda
Information Booklet
2014
About Mallee Sustainable Farming
Mallee Sustainable Farming (MSF) Inc. is a farmer driven
organisation delivering research and extension services to the
less than 350mm rainfall Mallee cropping regions of New South
Wales, Victoria and South Australia. MSF operates within a
region of over four million hectares, extending beyond Balranald
in the east to Murray Bridge in the west.
Our 17 year legacy
MSF Inc. formed in 1997 in response to recognition that
conservation farming practices had not been widely adopted
across the region. Therefore, there was a need to identify the
issues restricting the adoption of technology that would enhance
the development of profitable and sustainable farming systems.
During its first 16 years of operation, MSF has achieved a great
deal. Increases in farm profitability have been observed as a
result of MSF activities, along with environmental and social
gains. MSF continues to strive to be relevant to farmers’
information needs, whether in the sphere of cereal cropping or
livestock management.
Our members
The Mallee has approximately 2000 dryland farming families
whose farming activities include cropping (wheat, barley, vetch,
lupins and canola) and livestock (sheep for wool, lambs and
cattle for meat). An increasing number of these families are
members of MSF, receiving new and timely information on
research and best management practices. Such activities include
Farmtalk fact sheets, farm walks, trial sites, field days and
research compendium publications.
To become a free MSF member log onto www.msfp.org.au and
fill in our online form.
Contents
Trial Map................................................................................................................................................ 3
2014 Karoonda Field Day Program.................................................................................................. 4
Closing Mallee yield gaps using nutrition and break crops: A summary of 2009-2013
trials at Karoonda ................................................................................................................................ 5
Resistance status of brome grass in the SA Mallee ...................................................................... 9
Narrow windrow burning: entry point for harvest weed seed control .................................. 12
Nitrogen cycling in cereal stubble retained systems................................................................ 16
Sakura® 850WG herbicide for grass weed control in water repellent soil ........................... 18
Taking variable rate technology (vrt) science into the paddock ............................................ 20
Whole farm benefits and risks of earlier sowing ........................................................................ 26
Testing on-row and inter-row seeding across soil types .......................................................... 30
Weed Competitiveness of Barely Varieties ................................................................................. 34
Current and New Barley Varieties................................................................................................. 36
Vetch: More than just fodder .......................................................................................................... 39
Maximising the Nitrogen benefits of rhizobial inoculation ...................................................... 42
Wheat seed source and seed size effects on grain yield …………………………………….45
This Field Day is also supported by the Department of Social Services under the Strengthening
Communities Project.
Thank you to our Karoonda Field Day Sponsors:
Thank you to our Corporate Sponsors
www.msfp.org.au
2
www.msfp.org.au
3
2014 Karoonda Field Day Program
Session 1: Location – Marquee
• Tanja Morgan, TM Project Services: Resistance status of brome grass in the SA
Mallee
• Michael Walsh, AHRI: Resisting resistance: narrow windrow burning and other non –
herbicide options
Session 2: Location – Southern Station
• Gupta Vadakattu, CSIRO: Nutrient cycling in stubble retention cropping systems
• Rob Griffith, Bayer: Herbicide options for managing brome grass
• Chris McDonough, Rural Solutions: Taking the VRA science into the paddock
Session 3: Location – Northern Station
• Andrew Fletcher, CSIRO: Whole farm benefits and risks of earlier sowing
• Rick Llewellyn, CSIRO: On the row or off the row – that is the question
• WD Lewis: Technology to achieve inter-row sowing
Session 4: Location – SARDI Trial Station
• Simon Goss, SARDI: Weed competition in barley varieties
• Stewart Coventry, University of Adelaide: Current and new barley varieties
• Stuart Nagel, SARDI: Vetch varieties for Mallee farming systems
• Maarten Ryder, University of Adelaide: Maximising the N benefits of rhizobial
inoculation
• Shafiya Hussein, SARDI: Effects of seed size and seed source on wheat performance
10:00 am
10:30 am
11:30 am
12:30 pm
1:30 pm
2:30 pm
3:30 pm
www.msfp.org.au
Welcome: Michael Moodie, Mallee Sustainable Farming
Overview of the MSF research site: Therese McBeath, CSIRO
Navy Blue Group
Red Group
Gold Group
Session 1
Session 1
Session 4
Session 2
Session 3
Session 1
Lunch
Session 3
Session 4
Session 2
Session 4
Session 2
Session 3
Evaluation and Close
4
Closing Mallee yield gaps using nutrition and break crops: A
summary of 2009-2013 trials at Karoonda
Therese McBeath, Rick Llewellyn, Vadakattu Gupta, Bill Davoren, Damian Mowat, Jackie Ouzman,
Marta Monjardino (CSIRO) with Michael Moodie (MSF)
Take Home Messages
• There is strong support for the use of soil-specific nitrogen (N) management to improve
profitability and reliability of returns from fertiliser N on Mallee crop paddocks.
• The highest yielding part of the paddock is not necessarily where the return on extra N fertiliser is
highest- aim for where returns on each dollar of N applied are likely to be greatest.
• Whole farm analysis shows that shifting fertiliser inputs from heavy constrained soils to sandy
topsoils can have significant profit and risk benefits over several years but nutrient reserves need
to be monitored.
• The gross margins of break crops are usually riskier than for cereals but the effect of a legumebased break on cumulative wheat yield over the next couple of years has been relatively reliable.
• Increased N supply could be measured up to two years following the break and played a key role
in the break effects at Karoonda where the weed burden was low.
• Disease breaks tended to only last for one wheat growing season.
Background
There has been widespread use of continuous cereal on Mallee soils over the past decade with these
practices generally productive and relatively water use efficient. Although this has been profitable on
average, it can involve increasing levels of risk as input requirements increase. There are an increasing
number of crop paddocks suffering from declining nutrient and water use efficiency following lengthy
sequences of cereal. Weighing up the best N investment strategies in terms of profit and risk for
different soil types becomes particularly important. Increasingly there are paddocks with a ‘yield gap’
between yield potential and the yield received despite fine tuning of the management of N according
to soil types and the implementation of break crops (including pastures) to manage other nutritional
constraints, diseases and weeds has been tested. The best strategies for growers are based on a range
of measures that take into account yield, profit, return on investment and exposure to potential losses.
Field Trials
Trials were established in 2009 at a Mallee Sustainable Farming on-farm research site near Karoonda
(Lowaldie) to test soil-specific strategies and tactics for reducing risk and increasing profitability in
cereal-based rotations. Various treatments reflecting potential management practices were applied
across soil types covering a dune-swale system. Field results and crop & economic modeling are used
to identify the best long-term options and likely risk. Field trials involved N x P, break crops, and
pasture and cereal management strategies including N timing. All experiments are designed to
examine soil-specific effects and cover a range of soil types.
Break crops including legume, rye, brassica and pasture were grown in 2009 and 2010 and followed
by consecutive wheat crops until 2013. Wheat yield following these breaks were compared with a
continuous wheat treatment. All treatments were applied at four positions in the landscape: hill (deep
sand), mid-top, mid-slope and swale (heavy flat).
Several economic methods have been used including the use of crop simulation to test how well
different N fertiliser practices perform over a wide range of season types. This is used to test the
riskiness of different strategies by also including a range of N and grain prices in the analysis.
www.msfp.org.au
5
Key results
Over five years of continuous wheat, additional N (applied as urea) at sowing has increased returns
across the mid-slope and dune but most markedly in the dune (Figure 1). Nil fertiliser has been the
most profitable strategy on the heaviest most constrained flat in all years but N reserves are now
getting low (as suggested by a high protein response to N in 2013).
Applying N upfront gave a better gross margin than a late split application with most N applied at
tillering-stem elongation across most of the landscape. Applying in-season N earlier than GS31
appeared to improve responsiveness in 2013. Pasture produced in 2009 resulted in one of the best
gross margins across the landscape (swale through to crest). Growing pasture in 2010 resulted in a
gross margin penalty as it meant missing very high wheat yields in the swales in that year.
Pasture 09
$3,500
Pasture 10
district practice
Nil Fert
$3,000
High N Upfront
High N topdress
Hay 11
Cummulative GM (2009-13) $/ha
$2,500
$2,000
$1,500
$1,000
$500
$0
1
2
3
4
5
6
7
8
9
Lanscape Position (1 swale - 9 Dune)
Figure 1. Cumulative gross margins ($/ha 2009-2013) in response to a range of agronomic
treatments across the swale to dune system. Treatments have been applied since 2009. District
practice is 50kg DAP (9kg N). High N is an additional 67kg/ha Urea (total of 40 kg N).Pasture was a
volunteer medic-based pasture.
Using a case study farm (in this case 2400 ha wheat enterprise) we evaluated different N strategies
and rates in terms of a range of potential profit and risk measures (Figure 2).
www.msfp.org.au
6
Figure 2. Annual net profit outcome on a 2400 ha wheat enterprise for different growing season
deciles in response to low (30 kg Urea/ha) vs. high (80 kg Urea/ha) N input across all soil types and
low (30 kg Urea/ha) vs. soil specific (80 kg Urea on dune 50 kg Urea on mid and 20 kg Urea on swale)
N input.
Assuming other constraints are managed, there are both risk and profit advantages in shifting N
investment from some soil types to others. Even when considering that a farmer may want to forego
some potential average profit (eg. the extra profit gained in the highest rainfall seasons with high urea
input across all soil types) to reduce the variability in returns (aversion to risk) there were benefits
from increases in the level of N fertiliser application on the sandy dune soils above what is currently
considered district practice.
Other trials at the site have shown that break crops (e.g. lupins, peas, and pasture) have led to a
cumulative yield gain of approximately 1 t/ha of wheat over the next 2-3 wheat crops compared to
continuous wheat. About 2/3 of this is gained in the first year after the break.
Pasture (and other legume breaks) has been shown to lead to an important and timely supply of N in
subsequent crops with major wheat yield benefits. The benefits of a legume-based break to N
supply in the next crops go beyond starting N levels. Figure 3 shows a comparison from a low disease
year (2011) where N supply was likely to be a major driver of the differences in yield. Here the
dotted lines show readily available N (fertiliser N + soil mineral N to 60 cm) for high fertiliser input
(40 kg N) vs. 2010 pasture (in which the 2011 crop received 9 kg fertiliser N). The solid lines show
yields and that having a volunteer medic-based pasture in 2010 still caused a wheat yield boost
compared with the high N input treatment, despite the high N input treatment having more readily
available N at sowing.
www.msfp.org.au
7
5.0
4.5
4.0
2011 wheat yield 40 fert N
180
Readily available N 2010 pasture
160
Readily available N 40 fert N
140
2011 Wheat Yield (t/ha)
3.5
120
3.0
100
2.5
80
2.0
60
1.5
40
1.0
Readily available N at sowing (kg N/ha)
2011 wheat yield 2010 pasture
20
0.5
0.0
0
2
3
5
6
4
Landscape Position (2 swale-8 dune)
7
8
Figure 3. Wheat yields in 2011 (solid lines) following a 2010 pasture vs. high input of fertiliser N
plotted with the readily available N at sowing (fertiliser + soil N 0-60cm; kg N/ha). Fertiliser in 2011
wheat following 2010 pasture was 50kg DAP (9kg N) with an additional 67kg/ha Urea (total of 40 kg
N) on the 40 fert N treatment. 2010 pasture was a volunteer medic-based pasture.
Acknowledgements
Thanks to the Loller family for their generous support in hosting the trial, the Karoonda Mallee
Sustainable Farming advisory group, Jeff Braun and Anthony Whitbread. Funding for this work was
from the GRDC and CSIRO Agriculture Flagship.
Further information
Therese McBeath, CSIRO Waite Campus
[email protected], Ph 08 8303 8455
See our recent GRDC grower update articles for more:
Nitrogen:
http://msfp.org.au/wp-content/uploads/2013/06/Waikerie-Grower-Update-2014-Llewellyn130814.pdf
Break Crops:
http://msfp.org.au/wp-content/uploads/2013/06/Speed-Grower-Update-2014-mcbeath-230714.pdf
www.msfp.org.au
8
Resistance status of brome grass in the SA Mallee
Tanja Morgan, TM Project Services & Rural Solutions SA
Take Home Messages
• Currently group A and B herbicides are the most useful for selective in crop brome grass control
and resistance in brome grass to these chemical groups is on the rise.
• Using Intervix® in Clearfield cereals and canola is currently giving good brome control for many
but the risk of herbicide resistance developing is high.
• Intervix® resistant brome grass has already been found in the Mallee.
• When using herbicides plan to rotate modes of action and when using group A and B herbicides
have a plan to kill the survivors of any application.
Background
In 2013 the SAGIT funded brome project tested 40 brome samples from across the Mallee for
resistance to two group A and two group B herbicides. Farmers volunteered to have their brome grass
sampled, therefore the samples were taken from areas known to be problematic for brome grass. This
is unlike the random weed survey conducted by the University of Adelaide every 5 years where brome
is usually sampled by the fence and in some cases only a few plants may be found. The last random
survey in the Mallee was conducted in 2012.
2013 Results and the level of resistance to commonly used group A and B herbicides.
Rating
Verdict®
Haloxyfop
Select®
Clethodim
38
Atlantis®
Mesosulfuronmethyl
11
Intervix®
Imazamox
Imazapyr
39
Susceptible
14
Low resistance
24
2
26
-
Med resistance
2
-
2
-
High resistance
-
-
1
1
Samples
Resistant %
65
5
73
2
+
Much of the resistance that was found was low-level resistance, therefore some of the plants within
a population may still be controlled but a low percentage of plants are beginning to grow through an
application of herbicide at the rate tested.
In the field low-level resistance is often less obvious and difficult to pick up therefore the same
herbicides may continue to be used in a rotation for a long period of time. The problem keeps growing
each year the same herbicides are used unless an alternate method of control can be implemented to
kill the survivors and deplete the seed bank.
www.msfp.org.au
9
The picture above is showing what (from L-R) high, medium and low resistance looks like in ryegrass
in the green house.
What does this mean?
Group A & B chemicals currently give good control of brome grass in crop situations. If we lose them
to resistance then there are limited other in crop options for controlling brome.
It’s important to remember that 4 applications of a group B herbicide and between 6-8 applications
of a group A herbicide in a paddock could lead to a resistance problem.
Intervix® is now commonly used in Clearfield wheat, barley and canola and is an important herbicide
for brome control. It’s important to keep Intervix® in the tool kit for as long as possible so farmers are
urged to look at their herbicide histories and plan rotations that rotate chemical groups and
incorporate non-selective and non-herbicide control options.
Relying on Intervix® as a stand-alone brome control strategy will hasten resistance.
The sample pictured above is the first confirmed Intervix® resistant brome plant in the SA Mallee. This
plant (pictured left) has received 1.8L/ha of Intervix® and survived. The paddock where the brome
seeds were collected has a history of 2 applications of Intervix®, and a longer history of Logran® use.
www.msfp.org.au
10
Making Intervix® Last
• Use only one group B per season
• Use no more than 2 group B herbicides in any four year period and avoid consecutive years of
application
• Use Intervix® with other strategies e.g. pre-emergent herbicides, hay cut, crop-topping,
harvest weed seed capture and destruction
• Ensure survivors from any treatment don’t set seed
• Rotate chemical groups – use different modes of action.
Rotations for brome control
Controlling brome grass is a two to three year proposition and rotations should work to diminish plant
numbers over that time without relying on group B’s every year.
Non-group B options for control may include:
• Pastures – Very effective control with early grass selective plus spray topping (don’t rely on
spray topping alone). This option is good where brome numbers are high.
• Canola – grass selective herbicide plus windrowing options, desiccate
• Legume break crops – grass selective plus crop topping options, green/ brown manure
• Barley – higher seeding rates for crop competition, using metribuzin given a year with the right
soil conditions and low brome densities, best at the end of a three year rotation.
Do you think you have a resistance problem?
Monitoring paddocks after spraying is really important. Resistant weeds are now common and you
need to question why a spray application achieved a lesser result to what you were expecting.
Look for plants of similar growth stages and check for survivors after an application. Survivors can be
Quick Tested for resistance to a range of herbicides with an answer within a month.
Check the Plant Science Consulting website for more information, www.plantscienceconsulting.com,
or contact Dr Peter Boutsalis at Adelaide University, 0400 664 460.
Further information
Tanja Morgan, Jabuk, SA
[email protected] or 0429 395 918
www.msfp.org.au
11
Narrow windrow burning: entry point for harvest weed seed control
Michael Walsh, Australian Herbicide Resistance Initiative, University of Western Australia.
Take home messages
• Harvest represents an opportunity to target seed production of weeds to minimise their
impact on subsequent crops.
• Currently, the most widely adopted Harvest Weed Seed Control (HWSC) system in use in
Australia is narrow windrow burning
• The simplicity and low cost of narrow windrow burning has resulted in its adoption by an
estimated 50% of crop producers in Western Australia.
• Weed seed kill levels of 99% for both annual ryegrass and wild radish have been recorded
from the burning of wheat, canola and lupin narrow windrows
Harvest Weed Seed Control
Harvest Weed Seed Control (HWSC) exploits the biological attribute (weakness) of seed retention at
maturity in our most problematic annual weed species, annual ryegrass, wild radish, wild oats and
brome grass. This means that the seed heads remain intact at crop maturity enabling the weed seeds
to be collected during grain crop harvest. For example, in western Australian wheat crops we
measured the retention of over 80% of total production for annual ryegrass at a height (above 15cm)
that allows collection during harvest (Walsh and Powles 2014). These weed seeds enter and are
processed by the grain harvester and exit, mostly in the chaff fraction to be spread evenly back across
the paddock to become future weed problems. Typically the weeds present at crop maturity are the
ones we don’t want in the paddock because they have survived herbicide treatments etc. So crop
harvest represents an opportunity to target seed production of these significant weeds to minimise
their impact on subsequent crops.
Narrow windrow burning
Currently, the most widely adopted HWSC system in use in Australia is narrow windrow burning where
a chute mounted to the rear of the harvester concentrates all chaff and straw residues into a narrow
windrow (500-600mm) (Figure 1). These windrows are subsequently burnt, without burning the entire
crop field. The concentration of chaff and straw residues increases the duration and temperature of
burning treatment ensuring weed seed destruction. Weed seed kill levels of 99% for both annual
ryegrass and wild radish have been recorded from the burning of wheat, canola and lupin narrow
windrows (Walsh and Newman 2007). The simplicity and low cost of this system has resulted in its
adoption by an estimated 50% of crop producers in Western Australia.
Figure 1 a) Chaff chute mounted on the rear of a harvester to form narrow windrows during harvest.
b) Burning narrow windrows in wheat stubble in autumn (Mar. - Apr.)
Although it is easy to establish windrows during harvest it is a little more complicated to achieve an
effective windrow burn that achieves complete weed seed destruction following autumn.
www.msfp.org.au
12
During harvest the approach is to cut as low as possible to ensure the collection of as many weed
seeds as possible. This also provides a greater fuel source. Then the following autumn during burning
season the aim is for a slow hot burn the burns right to the soil surface where the weed seeds are
located at this time of year. Additionally, this burn needs to be achieved without burning the entire
paddock. Below are a few tips for achieving an effective burn:
1. Start in legume or oilseed crops. Windrow burning is very safe in non-cereal crops as there is
little or no residue to carry the fire away from the windrows. These windrows also burn
hottest. If you start soon enough and get your weed densities down you may never need to
burn windrows in cereal crops.
2. Burn with a light cross wind (5-10 km/hr) (Figure 1b). Wind is needed to fan the fire in
windrows that settle down over summer. However, a cross or even slight head wind slows the
fire down ensuring the windrows burn to the soil surface.
3. Legume and pulse windrows can be burnt as soon as the burning season commences. Leave
burning cereal windrows until last and when conditions are cooler.
4. If you are burning cereal windrows where the yield is greater than 2 t/ha then leave until just
before seeding and hopefully after a rainfall event.
5. Wet windrows can be burnt effectively. After a rainfall event wait until just the bottom 2-3cm
of the windrow is wet before burning.
6. Try windrow burning on weedy areas or paddocks first before committing to larger areas.
Chaff carts
Introduced in the 1980s chaff carts were the first HWSC system used in Australia (Figure 2). This
relatively simple system consists of a chaff collection and transfer mechanism, attached to a grain
harvester that delivers the chaff fraction into a bulk collection bin, usually a trailing cart. Chaff cart
systems have been shown to achieve the collection and removal of high proportions (80-90%) of seed
of the dominant crop-infesting weeds annual ryegrass, wild radish (Walsh and Powles 2007) and wild
oat (Avena spp.) (Shirtliffe and Entz 2005). Because of the large volume of material, the collected chaff
is typically dumped in chaff heaps in lines across fields in preparation for subsequent burning to ensure
weed seed destruction. Thus only the chaff residue is burnt with all the straw retained.
Figure 2. Chaff cart system in operation during commercial wheat crop harvest
www.msfp.org.au
13
Bale Direct System
The Bale Direct System consists of a large square baler directly attached to the harvester that bales
chaff and straw residues during grain crop harvest (Figure 3). This system was developed as a method
for effectively collecting harvest residues for subsequent use as livestock feed. The Bale Direct System
can remove 95% of annual ryegrass seed entering the harvester (Walsh et al. 2013; Walsh and Powles
2007). However, the availability of suitable markets for the baled material has limited the adoption of
this system in Australia.
Figure 3. Bale direct system collecting and baling chaff and straw residues during wheat harvest.
Harrington Seed Destructor
The Harrington Seed Destructor (HSD) is a trailer mounted, cage mill based chaff processing system
(Figure 4). Chaff is delivered from the rear of the harvester to the cage mill which processes this
material sufficiently to destroy the contained weed seeds. This system has been shown to result in the
destruction of over 90% of annual ryegrass, wild radish, wild oats and brome grass seed present in the
chaff fraction during harvest (Walsh et al. 2012). A distinct advantage of this HWSC system is the
retention of all harvest residues, a critical attribute for soil moisture and nutrient conservation.
Figure 4. Harrington Seed Destructor
www.msfp.org.au
14
Field comparison of HWSC systems
When HWSC systems are correctly implemented during commercial crop harvest they will deliver the
same impact on annual weed populations. Comparison of HWSC systems in 25 field trials conducted
across Australia over the 2010 and 2011 harvests found chaff cart, narrow windrow burning and HSD
systems provided similar levels of annual ryegrass seed destruction (Walsh 2012). This extensive
evaluation determined that at each site these three HWSC systems all produced the same level of
reduction in subsequent annual ryegrass emergence. On average there was a 60% reduction in
emergence due to HWSC treatment. However, at low annual ryegrass density sites emergence was
reduced by up to 80% while at low density sites there was only a 30% reduction in emergence.
The value of HWSC systems
The real value of HWSC treatments is their impact on weed populations that have persisted through
early-season in-crop weed control. Implementation of HWSC treatments, in conjunction with effective
early-season herbicide treatments, results in the reduction of weed populations to very low densities.
The impact of herbicides plus HWSC over 10 consecutive seasons (2002-2013) was monitored on incrop annual ryegrass populations in 25 large, commercial Western Australian cropping fields (Walsh
et al. 2013). This study commenced with producers nominating “problem fields” with high (35-70
plants m-2) in-crop annual ryegrass densities. Over 12 consecutive growing seasons, weed
management practices were implemented on these fields with the aim of reducing annual ryegrass
populations to acceptably, low plant densities of < 1 plant m-2. As expected, effective herbicide
treatments reduced in-crop annual ryegrass populations to < 5 plants m-2 within five consecutive
growing seasons. However, it was only in the fields where both early-season herbicides and HWSC
was routinely practiced that the targeted low weed density of < 1 plant m-2 ensued. In these fields,
annual ryegrass numbers were reduced from an average of 35 plants m-2 in 2002 to just 0.5 plants m2
. In contrast, where herbicides alone were used, average annual ryegrass plant densities remained
well above 1 plant m-2.
Summary
The destruction of weed seeds at or after grain harvest facilitates weed seed bank decline and when
combined with conventional herbicide use, can drive weed populations to very low levels. Growers
routinely including strategies to target weed seeds during crop harvest, as part of herbicide-based
weed management programs, are now realising significant weed control and crop production
benefits. When combined with an attitude of zero-weed tolerance there is now clear evidence of a
sustainable weed control future for crop production systems.
References
Shirtliffe, S. J., and M. H. Entz. 2005. Chaff collection reduces seed dispersal of wild oat (Avena fatua)
by a combine harvester. Weed Sci. 53:465-470.
Walsh, M. J. 2012. Harvest Weed Seed Control. GRDC agribusiness crop updates. Goondiwindi.
Walsh, M. J., R. B. Harrington, and S. B. Powles. 2012. Harrington seed destructor: A new
nonchemical weed control tool for global grain crops Crop Sci. 52:1343-1347.
Walsh, M. J., P. Newman, and S. B. Powles. 2013. Targetting Weed Seeds in-crop: A New Weed
Control Paradigm for Global Agriculture Weed Technology in Press.
Walsh, M. J., and S. B. Powles. 2007. Management strategies for herbicide-resistant weed
populations in Australian dryland crop production systems. Weed Technol. 21:332-338.
Walsh, M. J., and S. B. Powles. 2014. High seed retention at maturity of annual weeds infesting crop
fields highlights the potential for harvest weed seed control. Weed Technol. Accepted.
www.msfp.org.au
15
Nitrogen cycling in cereal stubble retained systems
Vadakattu Gupta, Therese McBeath, Rick Llewellyn, Stasia Kroker and Bill Davoren
CSIRO Collaborators: John Kirkegaard, Alan Richardson and Enli Wang
Funding: CSP00186, MSF00003, CSP00138
Take Home Messages
• The management of cereal stubble is likely to influence the microbial activities related to cycling
of nutrients (nitrogen and phosphorus) and supply to growing crops.
• We have implemented trials using 15N isotope labelled Urea, to directly trace the amount of
nitrogen supplied to subsequent crops from cereal stubbles under different stubble management
practices (retained, incorporated, mulched)
Crop residues are one of the major sources of carbon (C) for soil biota in low fertility agricultural soils
of Southern Australia and stubble retention can provide benefits through changes in soil physical,
chemical and biological properties. Although stubble retention benefits are expected to be realised in
all soil types, the magnitude and nature of change in biological functions can vary depending on type
and timing of stubble management and is influenced by soil type and environmental factors (e.g.
rainfall). Soil type and environment can modify the response of different soil biota to stubble
management resulting in variation in the fate of stubble N and soil N cycling (Figure 1).
SOM
Residues
Organic N
FLN2 f ix
N2O&N2
CO2-C
1
NH4-N
2
NO3-N
MB-C&N
Figure 1. A simplified conceptual model showing key biological processes involved in N cycling and
availability as influenced by stubble management in cropping soils. (1) Biological activity/benefit, (2)
Mineralisation/Immobilisation balance.
Environmental factors also dictate the temporal dynamics i.e. succession of microbial communities
which in turn have the potential to influence the levels of different microbial functions. Thus choosing
an appropriate stubble management strategy may be critical to gain maximum benefits for soil
fertility, in terms of nutrient mineralisation, carbon turnover and maintaining biological health. For
example, in the light textured soils, stubble treatment may have a greater effect on N mineralisation,
while in clay soils the effect is more likely from the presence of an extra carbon source for biological
activity.
www.msfp.org.au
16
Different stubble treatment practices can also have varying effects on the associated microbiology
influencing nitrogen mineralisation and immobilisation which affect both the timing of release of
nitrogen into plant available pools. Cereal stubble is a critical carbon source for non-symbiotic (NS) N
fixation by free-living N fixing bacteria hence stubble removal by burning or grazing would have
negative impact on the amount of N fixation. The amount of NS-N fixation is generally higher
immediately after harvest (Jan to Feb) and decreases as summer progressed. The amount of NS-N
fixation in wheat stubble retained systems, during summer months (2012), at Karoonda ranged from
0.2 to 1.5 kg N / ha / day when adequate soil moisture was present. Currently we lack detailed
knowledge on several aspects of nitrogen dynamics under field conditions. Such knowledge is critical
for accurate predictive modelling and to develop best bet nutrient management options in stubble
retained systems by driving improvements in the assumptions that underpin N management decision
tools.
Our aim is to quantify the effect of stubble management on the timing and amount of N release &
availability with varying stubble loads, treatment and soil environment.
As part of a new GRDC project (CSP00186) we are conducting focussed studies at Karoonda in South
Australia, Temora in New South Wales and Horsham in Victoria, to strengthen our knowledge on
seasonal changes in the (1) biological value of stubble (2) mineralisation: immobilisation balance
(ratio) and (3) the direct supply of N from stubble to crops as influenced by stubble management.
Further information
Vadakattu Gupta
Email: [email protected] ; Tel: 08-8303 8579
Upcoming MSF Events to Keep an eye out for!
Kyalite (NSW) – 2nd Last Week in September 2014 Date TBC
Ouyen (VIC) – Friday 3rd October 2014 Date TBC
Keep updated on our events by going to http://msfp.org.au/events/
You can also keep up to date with MSF by liking our Facebook Page:
www.facebook.com/MalleeSustainableFarming
MSF also has some new videos on our YouTube channel, this includes GO pro footage of different seeder
setups in action, as well as a couple of videos about utilising perennials such as saltbush to improve
productivity on constrained soils in the Mallee.
https://www.youtube.com/MSFMildura
www.msfp.org.au
17
Sakura® 850WG herbicide for grass weed control in water
repellent soil
Rob Griffith, Bayer 0428 694 628 [email protected]
Key Messages
• The level of weed control of Sakura is influenced by moisture before and after sowing
• Improved control of brome grass occurred when the herbicide was applied and incorporated
by sowing to dry soil prior to the season breaking rainfall event
• Adding a tank mixture partner such as trifluralin may improve weed control where moisture
is marginal after application and sowing.
Background
The effects of moisture and water repellent soil can challenge the performance of pre-emergent
herbicides. The pre-emergent herbicide Sakura has excellent activity on a range of problem grass
weeds including barley grass, annual ryegrass and suppression of brome grass. The level of weed
control of Sakura is influenced by moisture before and after sowing. Water repellent soil adds another
complicating factor particularly if the soil is moist at sowing and rainfall following seeding does not
move the herbicide to where weed seeds are germinating.
Methods
Trial work has been conducted over two seasons at the MSF trial site at Lowaldie. The aim of this
research was to evaluate Sakura for grass weed management in wheat grown in water repellent sand.
The details of trials conducted in 2012 and 2013 are provided in Table 1.
Table 1. Details of the trials conducted in 2012 and 2013/
Crop / Target
Application
Crop
Wheat, Kord (70 kg/ha)
Date
See below
Sowing
Knife point + press wheel
Timing
Pre-emergent
Sowing date
See date of spray timing below
Water Volume 65 L/ha (coarse droplet)
Target 1
brome grass (Bromus diandrus)
Brome grass 2012 612 plants / m2
density
2013 114 plants / m2
Ground cover 50% stubble
Soil moisture
2012 moist, 2013 dry
Spray timing
Time
Temp
RH % Cloud cover
Wind
Soil moisture
o
2012 31/05/12 0930-1030
16 C
67%
0%
5-10 km/h NE
moist
2013 28/05/13 0845-1000
11.5oC
88%
10%
5-8 km/h NE
dry
Results
In 2012 the pre-emergent herbicides were incorporated by sowing (IBS) after the season break at the
end of May. Weed control in this trial was poor due to high weed numbers, weed seeds beginning to
germinate prior to sowing and herbicide not being incorporated effectively by rainfall after sowing.
The 2013 trial in contrast had the herbicides applied IBS before the rain event and improved levels of
weed control resulted from weed seeds coming into contact with herbicide prior to germinating.
www.msfp.org.au
18
Improved control of brome grass occurred when the herbicide was applied and incorporated by
sowing to dry soil prior to the season breaking rainfall event in 2013. The sowing operation occurred
after rainfall in 2012 and weeds did not come into contact with the herbicide early enough.
Adding a tank mixture partner such as trifluralin may improve weed control where moisture is
marginal after application and sowing. A post emergent herbicide may also be required.
* Percentage control based on plant numbers. Sakura® is a Registered Trademark of Kumiai Chemical
Industry Co. Ltd.
Acknowledgements
Thankyou Peter & Hannah Loller for providing the site for the trial and Bill Davoren of CSIRO for his
assistance with site management.
Further Information
Rob Griffith, Bayer
Phone 0428 694 628
Email [email protected]
www.msfp.org.au
19
Taking variable rate technology (vrt) science into the paddock
Chris McDonough, Rural Solutions SA
Take Home Messages
• Success with Variable Rate Technology involves both paddock zoning according to key paddock
differences and then working out the optimal management for each zone.
• Zone management plans must be adjusted to account for seasonal opportunities and risks by
understanding moisture availability and key soil type characteristics.
• The paddock scale VRT trial at Lowaldie combines key research data with soil testing, mapping,
soil moisture probe and weather station data to optimise the farmer’s profitability.
Introduction
This Mallee Challenge Paddock trial aims to take the best information from the CSIRO trials over the
last five years and apply it to the rest of the paddock using Variable Rate Technology (VRT) to improve
the targeting of inputs to landscape potential to help increase farm profitability.
This paddock also aims to test the application of soil moisture probes in improving strategic
management decisions based on up to date Plant Available Water (PAW) for different paddock zones.
Moisture probes have recently been installed by the Natural Resources SA Murray-Darling Basin
(NRSAMDB) in the deep sand, mid-slope and heavy flat soil zones. The information from these probes
along with the weather station data that is accessible through the NRM website, will greatly add to
our understanding of our plant/soil/water dynamics.
VRT keys to success
The key elements to success with applying VRT are:
1. Establishing different paddock zones that are worth managing separately.
2. Working out optimal management strategies for each zone, which may depend on PAW and
fertility, yield potential, seasonal factors, economic limitations, common sense, attitude to
risk and the experienced “gut feel” factor. It will also allow for in season adjustments based
on how the season develops.
3. Leaving some strips of higher or lower rates to compare results and learn from.
4. Objectively assessing and comparing yield and quality results to more accurately assess
management strategies and make adjustments for the future. This is a dynamic learning
process that must be adapted to your farm and farming system. There is no hard and fast
“one size fits all” approach.
It should also be noted that while it was the intention of the farmer to have full VRT in his tractor at
this time, circumstances did not allow this, and so the variable rates were applied manually between
the farmers fertiliser rate dials in the cab, and me telling him when to change using a GPS tablet. Not
perfect but we managed for now.
www.msfp.org.au
20
Defining Paddock Zones at the Loller Paddock Site
Paddock zones were initially based on original EM38 mapping and deep soil testing, using the “Your
Soil Potential” model to understand the characteristics of the different soil types, fertility issues and
estimated crop lower moisture limits. For this paddock it was decided there were 4 distinct land zones
that would benefit from different crop management strategies. These are described as:
1. Heavy flats with high subsoil constraints.
2. Loamy flats
3. Mid-slope sand
4. Deep sand
These zones were delineated using corresponding EM38 values, and are presented in Figure 1.
VRT Application
Paddock Zones
1. Heavy flats
2. Loamy flats
3. Mid-slope
4. Deep sand
CSIRO
Trial
Area
Figure 1. Four soil management zones of trial VRT paddock.
www.msfp.org.au
21
Deciding on optimal zone rates
Key general principles that should be followed:
1. Estimate crop potentials for each soil type, based partly on stored plant available water
(PAW) going in to this season,
2. Assess the amounts of nutrition that may be required to reach those potentials.
3. Consider the existing nutrition each soil might already have, based on texture, rotation and
paddock history. Ideally soil testing is best to gain a more accurate understanding of this for
each zone. Work out the difference between what is required and what is available to then
decide how much fertiliser you will need to supply to make up the difference.
4. Given that you will have a limited fertiliser budget, consider the risks of growing crops on
particular soil types and focus on targeting your efforts where financial returns are most
likely to be achieved. It is also important to apply existing knowledge and experience for
both the optimal rates and timings of applications (this site has research data that will assist
here).
At this site we inputted the soil test information into the “Mallee Calculator” (downloadable from
the MSF Website at http://msfp.org.au/tools/mallee-calculator/ to assist with steps 1-3 to estimate
fertiliser requirement for the various soil zones.
Table 1. Soil Test and Program Results for fertiliser considerations.
Org Carbon
Colwell P
Est. PAW
Est. PAN
Pot. Yld
N Required
Heavy Flat
1.8%
38 ppm
15 mm
67
2.1
35
Loam
0.84%
42 ppm
40 mm
76
2.8
70
Mid-slope
0.81%
19 ppm
56 mm
46
2.2
64
Deep Sand
0.64%
27 ppm
36 mm
74
2
50
Considering Seasonal Factors (high early moisture) with Soil Type Characteristics.
Heavy soils with high subsoil constraints may have started with medium PAW this season, depending
on rooting depth, and being more fertile will have high plant available nitrogen (PAN) from
mineralization in the surface at seeding time. Yield potential should be reasonable, but may require
spring rain to sustain bulky early growth. If late rain comes these soils tend to mineralize nutrients
and generally look after themselves.
CSIRO trials have shown little to no response to added fertiliser on these soils over a number of
seasons, and recommend that fertiliser from these areas would be better applied to mid-slope and
deep sand areas.
Loamy flats with good rooting depth should have very high yield potential this season with very high
PAW. Although they are generally fertile and should have good N levels at seeding time, I expect
that they will need extra N later in the season to fulfil their increased yield potential.
Mid-slope sands should have reasonable PAW with a full moisture profile however will have less
capacity to mineralise and hold onto nutrients, so may need higher levels up front or earlier in the
season. While these soils are potentially the best performing in lower rainfall years, they still have
excellent potential this year but will require extra inputs to achieve this.
www.msfp.org.au
22
CSIRO trials have shown yield responses to high nitrogen (80kg/ha) and phosphorus (10kg/ha) on
these Midslope sandy soils over a number of seasons.
Gutless sands are low in fertility and often have low water holding capacity. While they need to be
well managed to also overcome weed, root disease and compaction issues and can often respond
well to higher phosphorus and nitrogen application, you must be very careful not to be throwing
good money into a less dependable situation and only you really know these soils on your farm.
CSIRO trials have shown high responses to added high nitrogen and phosphorus fertiliser on these
sandy soils over a number of seasons with high N at seeding giving the best results.
Shallow stony soils can have reasonable surface fertility, but high pH and free lime can decrease
microbial activity and increase nutrient tie up. While it is good for them to be starting off wet, they
will always have limited PAW and require good spring rains to pull them through. Generally these
are also higher risk soils and are not where I would be targeting my limited fertiliser budget into this
season. None of these soils featured at this Lowaldie site.
Given the high levels of early season moisture that had greatly increased yield potential and after
discussion with the CSIRO research officers, the following rates were chosen for the VRT sections of
the paddock. The rest of the paddock received the farmer’s standard rate. While on balance the VRT
will be expending more on fertiliser than the farmer practice, rather than just redistributing the same
amount of fertiliser, it was thought justified based on the much higher yield potential that will require
extra nutrition to achieve.
Table 2. Fertiliser rates chosen for the paddock for this season.
Zone
Soil
Seeding
Actual Midseason Urea
rate used
(kg/ha)*
50
1
Heavy Flat
30
30
Planned
Mid-season
Urea Rate
(kg/ha)#
10
2
Loam
50
50
20
50
3
Mid-slope
60
60
40
50
4
Deep Sand
40
40
30
50
Farmer Flat
Rate
All soils
40
40
0
0
19:13 rate
(kg/ha)
Urea Rate
(kg/ha)
# rates were to be revised based on the Growing Season Rainfall (GSR) and moisture probe data
findings.
*Due to current farmer equipment, VRT was not available for post seeding urea spreading, so it was
decided to top dress half of the VRT area with a flat rate of 50kg Urea. Yield and protein results should
reveal what were the optimal rates at the end of the season.
www.msfp.org.au
23
The use of soil moisture probes
While the shifting and re-establishment of three soil probes has caused some data delays at this site
this year, is expected that through next year we will be able to reasonably track plant available water
through the season on various soil zones.
2014 soil probe data from other Mallee sites with multiple moistures probes has highlighted their
value in improving our understanding of soil/water/plant dynamics as well as the variations between
various soils. While it is early days yet and it won’t be until harvest before we can more accurately
assess crop lower limits and PAW and there are indications that there are limitations to using
capacitance probes in soils with higher subsoil salinity, it is hoped that these will become a useful tool
for farmers in coming years. This may be through tapping into data from local existing probes or
farmers acquiring their own. There are now 28 soil moisture probes in dryland agriculture across the
Mallee at 11 different paddock sites that will help us assess their usefulness and applicability.
The following graphs highlight these soil moisture differences at a Mallee Challenge site with 4 probes
near Paruna. These are on the same paddock experiencing the same rainfall.
Fig. 2 Non-wetting sand showing water passing straight through the rootzone.
Fig. 3 Loamy Flat appearing to hold all the same water in the top 50cm.
www.msfp.org.au
24
Summary
This site is a work in progress, in terms of getting the right equipment, understanding the soil zones,
seasonal data, soil moisture probe information and best applying soil research results. It is hoped that
in coming years this paddock will clearly demonstrate the advantages of VRT, and highlight the key
principles that should be applied by Mallee farmers to use on their own farms.
Acknowledgements
The Mallee Challenge program has been jointly funded by Caring for Our Country and the NRSAMDB
through Mallee Sustainable farming. Both Rachael May and Jeremy Nelson of the NRSAMDB have
contributed greatly to the programs activities.
Further information
Chris McDonough, Loxton SA
[email protected] 0408085393
Upcoming MSF Events to Keep an eye out for!
Kyalite (NSW) – 2nd Last Week in September 2014 Date TBC
Ouyen (VIC) – Friday 3rd October 2014 Date TBC
Keep updated on our events by going to http://msfp.org.au/events/
You can also keep up to date with MSF by liking our Facebook Page:
www.facebook.com/MalleeSustainableFarming
MSF also has some new videos on our YouTube channel, this includes GO pro footage of different seeder
setups in action, as well as a couple of videos about utilising perennials such as saltbush to improve
productivity on constrained soils in the Mallee.
https://www.youtube.com/MSFMildura
www.msfp.org.au
25
Whole farm benefits and risks of earlier sowing
Andrew Fletcher, CSIRO Agriculture
Take home messages
• The benefits/risks of early sowing need to be evaluated at a whole farm level
• An early start to sowing increases yield of both the early sown paddock but also paddocks sown
later in the seeding program
• Early sowing may increase the risk of frost but this could be offset using later maturing varieties.
• Larger cropping programs will need to begin sowing earlier in order to get the whole program
sown in a timely way.
Introduction
Timeliness of sowing is one of the keys to profitable grain farming. For every one day delay in sowing
past the optimum date yield decreases by approximately 20 kg/ha. In many parts of the Australian
wheat belt ANZAC day has been the traditional date to begin sowing programs. Later starts are used
in some areas to reduce the impact of frost. With erratic opening rains in autumn, increasing size of
farms, questions about investing in larger sowing machinery, and a focus on improving yields, interest
in early sowing has increased.
Some of the benefits of early sowing include: increased yields and the ability to sow larger cropping
programs without investments in more equipment, and a potential reduction in terminal drought and
heat stress events during grain filling. The key production risk is a potential increase in frost events
during flowering. Balancing these benefits and risks is a major challenge for farmers. A desktop
simulation was undertaken to evaluate the potential benefits and risks of early seeding at Karoonda.
Approach
Simulations were run for 41 years (1971-2011) at Karoonda. The APSIM simulation model (the model
behind Yield Prophet) was used to simulate the yield of a set of individual wheat paddocks making up
a cropping program. Cropping programs were simulated that required 10, 20, or 30 days to complete
sowing (a function of sowing machinery capacity and the area of the cropping program), beginning on
either 25 April, 5 May, 15 May and 25 May (regardless of whether or not a the crop would germinate).
Sowing began on each date regardless of rainfall. This meant that crops were sown dry when
necessary. A mid-fast wheat variety was sown in all paddocks. The proportion of the program affected
by heat during grain filling (maximum exceeding 35°C) and frost at flowering (minimum below 0°C)
was quantified, but yields were not discounted for these effects.
Results and discussion
Average farm yields were similar for a 25 April and 5 May start to sowing. For every delay in the start
of sowing after 5 May there was a penalty in average farm yield of approximately 10kg/ha/day. For a
5 May start to sowing farm yields were highest for a 10 day sowing program and decreased
progressively as the days required to complete the sowing program increased (Figure 1). As the size
of the sowing program increased the need to start sowing earlier was greater.
www.msfp.org.au
26
Average wheat yield across farm (kg/ha)
3000
2500
2000
1500
25-Apr
10 day sowing
program
20 day sowing
program
30 day sowing
program
5-May
15-May
Sowing date of first paddock
25-May
Figure 1. Effect of the date of the start of the sowing program on mean simulated farm wheat yield.
Data are averaged across 41 seasons and presented for a sowing program of 10, 20 or 30 days. Yield
estimates do not factor in the effect of frost or heat stress.
The yield benefit of earlier sowing was due to an increase in yields of all paddocks within a program,
but especially the later sown paddocks. An example for 1989 is provided in Figure 2. The first wheat
paddocks sown with a 25 April start date and a 5 May start date all had a yield of 2.4t/ha. However,
this was achieved over half the area of the cropping program that started on 25 April but on only 2
paddocks if the cropping program started on 5 May. The yield of the final paddock sown was 0.3 t/ha
greater for a 25 April start to sowing compared with a 5 May start to sowing.
There is a delicate trade-off between frost and heat stress that needs to be considered when deciding
when to start sowing. Both frost events and heat stress can have important impacts on yield and
quality. For each delay in the start of sowing the proportion of the crop frosted during flowering
decreased (Figure 3). For 25 May start of sowing the risk of frost during flowering was 0. However,
each delay in seeding also meant that the proportion of crop hit by heat stress during grain filling
increased, and more markedly than the decrease in frosted area. The risk of heat stress during grain
filling approximately doubled when the start of sowing was delayed from 25 April to 25 May. As the
size of the program increased the balance between the two stresses changed. Heat stress has more
impact in the 30 day program than in the 10 day program because more paddocks were sowon later.
Thus, as the size of the cropping program increases there is a need to take more of a risk with frost in
order to minimise the impact of heat stress. This analysis included only one variety of wheat. There is
potential to manage some of this frost risk by adjusting variety as the sowing program progresses.
www.msfp.org.au
27
3000
1989
(20 day seeding program)
Individual paddock yield (kg/ha)
2500
2000
1500
25 Apr start
5 May start
15 May start
1000
500
0
25-Apr
5-May
15-May
25-May
Sowing date of individual paddock
Figure 2. Example of simulated individual paddock yields for a 20 day sowing program beginning 25
Apr, 5 May and 15 May in 1989.
Conclusion
The date on which to start sowing is one of the most important but also one of the more difficult,
decisions to make. Earlier sowing can increase yields but there is also an increase in frost risk. The size
of the cropping program will be an important consideration. Larger programs will need to begin
sowing earlier to minimise the impact of heat stress and terminal drought, and in doing so run the risk
of encountering more frost damage.
Acknowledgement
This research was funded by the Grains Research and Development Corporation under the project
“identification of priority RD&E areas for the practice of dry seeding into residues in the W.A. Wheat
– Belt” (Project no: WAN00020).
Further information
Andrew Fletcher
CSIRO Agriculture
PB5, Wembley, WA 6913
[email protected], 08 93336467
www.msfp.org.au
28
20
1
10
30-Apr
10-May
5-May
15-May
Sowing date of first paddock
20-May
0
25-May
60
20 day program
50
4
40
3
30
2
20
1
0
25-Apr
10
30-Apr
5
4
3
5-May
10-May
15-May
Sowing date of first paddock
20-May
0
25-May
60
30 day program
50
Frost
40
Heat
30
2
20
1
0
25-Apr
10
30-Apr
5-May
10-May
15-May
Sowing date of first paddock
20-May
0
25-May
Percentage of crop heat stressed
30
2
Percentage of crop heat stressed
40
3
5
Percentage of crop frosted
50
4
0
25-Apr
Percentage of crop frosted
60
10 day program
Percentage of crop heat stressed
Percentage of crop frosted
5
Figure 3. Impact start of seeding on the average proportion of crop frosted or heat stressed for a 10,
20, and 30 day program.
www.msfp.org.au
29
Testing on-row and inter-row seeding across soil types
Rick Llewellyn, Vadakattu Gupta, Therese McBeath, Bill Davoren, Damian Mowat, Stasia Kroker,
Marcus Hicks (CSIRO) with Michael Moodie (MSF)
Take Home Messages
• There is potential for improved crop establishment conditions on sandy soils by on-row (or
near-row) seeding
• Prior to sowing in 2014 at Karoonda, topsoil moisture and soil nitrogen was higher on the
previous year’s crop row
• Fusarium and Take-all inoculum levels were lower and therefore more favourable in the interrow.
• Work is continuing on other sites and seasons and will include assessment of weed
establishment and weed seed production.
Background
Trials at the Karoonda site over recent years have highlighted the benefits of strong early crop
establishment and nutrition, particularly on sands. Non-wetting sands have presented additional
challenges. Global Positional System (GPS) guided seeding is increasingly common and presents the
opportunity for strategic placement of seed in relation to last season’s crop rows. In 2014, trials were
established at Karoonda and Loxton to examine when and where on-row (or near-on-row) seeding
may have benefits over inter-row seeding in stubble-retained systems. Preliminary results in relation
to soil water, nitrogen, and soil disease and crop establishment are presented below. The implications
for weed management are also being evaluated over the course of the trial.
The trial
Plots were sown with Corack wheat at two times:
• Early: 30th April
• Late: 14th May
For each time of sowing, this year’s crop was sown either on or very close to the previous year’s crop
row or between last year’s crop row. The row spacing used was 28 cm. All plots were sown into cereal
stubble and received DAP @ 50 kg/ha and Urea @ 24 kg/ha. Plots cover two main soil types (swale
and dune). The top soil was generally wetter at the time of the earlier sowing and had dried
substantially at the time of the later sowing (Figure 2).
Measurements will include disease risk, disease incidence, starting N and water, microbial activity,
nutrient supply potential, crop emergence, biomass and weed densities and growth.
www.msfp.org.au
30
Results
Soil conditions at seeding
Nitrogen
Distribution of mineral N prior to seeding is shown in Figure 1. Starting N levels were very low on the
dune, however across both soil types higher surface (0-10 cm) N levels were measured under last
season’s rows compared to in the inter-row.
Figure 1. Pre-seeding 2014 mineral nitrogen from soil cores taken on last year’s crop rows (on) and off
last year’s crop rows (inter). Sample depth increments are in centimetres.
Water
Soil water (0-10cm) prior to seeding is shown in Figure 2. Shallow soil water was higher under last
year’s rows compared to the inter-row, especially on the dune. Across both soil types and time of
sowing, the differences in soil water was about 5 mm between on row and the inter-row.
12.0
16.0
14.0
12.0
10.0
On row
8.0
Inter row
6.0
4.0
2.0
0.0
Volumetric moisture mm
Volumetric moisture mm
18.0
10.0
8.0
On row
6.0
Inter row
4.0
2.0
0.0
Swale
Dune
Swale
Dune
Figure 2. Pre-seeding soil water (0-10cm) from soil cores taken on last year’s crop rows (on) and off
last year’s crop rows (inter). Early sown is shown on left; late sown is shown on right.
www.msfp.org.au
31
Crop Emergence
Crop emergence on the dune was higher when the crop was sown on last year’s crop row (Figure 3).
140.0
120.0
80.0
On row
60.0
Inter row
40.0
20.0
0.0
Swale
Plants/m2
Plants/m2
100.0
100.0
90.0
80.0
70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0
On row
inter row
Swale
Dune
Dune
Figure 3. Crop establishment. Early sown is shown on left; late sown is shown on right.
Disease
Inoculum levels for soil borne pathogens (Takeall (Ggt), Fusarium) at seeding were generally higher on
the row compared to inter row (Figure 4 and Table 1). Rhizoctonia inoculum (Rhizoctonia solani AG8)
levels were not different between on-row and off-row as it forms hyphal networks whereas the others
are more closely associated with decomposing stubble material.
Quantity of pathogen DNA (log DNA +1 / g soil)
4.5
4
LSD P<0.05)
Ggt
Rs AG8
0.234
0.357
F.pseudograminearum
0.372
3.5
3
2.5
2
1.5
1
0.5
0
On Row
Inter Row
Dune
www.msfp.org.au
On Row
Inter Row
Swale
32
Figure 4. Disease inoculum levels for Takeall (Ggt), Fusarium (F. pseudograminearum) and Rhizoctonia
(RsAG8) in soil on last year’s crop rows and in the inter-row.
Table 1. Disease risk ratings Takeall (Ggt), Fusarium (F. pseudograminearum) and Rhizoctonia (RsAG8)
in soil on last year’s crop rows and in the inter-row.
Dune
Swale
Location
On Row
Inter Row
On Row
Inter Row
Ggt
Medium
BDL
Medium
BDL
Rs AG8
Medium
Medium
High
High
F.pseudograminearum
Med-High
BDL
High
Low
*BDL = Below Detection Level
Root disease scores for rhizoctonia at 8 weeks after seeding were significantly higher on dune but no
significant difference between on row and inter row were found. Fusarium and Take-all
measurements have not been completed so far.
Figure 5. Rhizoctonia root scores for wheat plants sown on last year’s crop rows and between last
year’s crop rows. The higher the score the greater the level of disease impact on crop roots. LSD
(P<0.05=0.3).
Acknowledgements
Thanks to the Loller family for their generous support in hosting the trial and Mallee Sustainable
Farming. The Loxton site is on the property of Bulla Burra. Funding for this work is from the GRDC and
CSIRO Agriculture Flagship.
www.msfp.org.au
33
Weed Competitiveness of Barely Varieties
Simon Goss and Rob Wheeler (SARDI)
Take Home Messages
• Using competitive varieties as a form of weed control is becoming more important
• Fathom, Scope and Skipper are seen as some of the best varieties in terms of weed
competitiveness
• Growers should select varieties for different paddocks depending on their weed history
• Competitive varieties is another tool in the fight to reduce weed seed banks
Why complete this work
With farmers continually increasing their heavy reliance on herbicides, using competitive varieties is
a way of pro-longing herbicide life and reducing weed seed set. Selecting good competitive varieties
is another tool along with break crops and the use of Clearfield varieties. Barley is usually placed at
the end of a rotation where nutrient levels are lower and when weed seed banks are higher. With
weed pressure often being higher during the barley phase of the rotation there is a need for varieties
to have good levels of weed competitiveness. As all varieties differ in their growing patterns, biomass
production and early vigour, it is necessary for us to assess how these traits affect their grain yield and
the ability to reduce the seed set of weeds.
How has this been done?
Plot Size: 1.75 m x 10m
Fertiliser: 70kg of DAP
Seeding date: 19th of May 2014
Varieties: Scope, Grange, Compass, Maritime, Navigator, Hindmarsh, Commander, Skipper, Fathom,
Wimmera, Moby and Mace wheat.
This trial has 12 different commercial barley varieties including Moby which is a forage variety and
Mace wheat. All varieties have six replications with three of these planted with oats to resemble
weeds. These were planted before the barley with some being below the ground and others being
above to resemble a normal seed bed.
A trial almost identical to this year was completed at this site last year. This showed a similar result to
other trials which were completed at Turretfield near Gawler. Results from last year’s trial can be seen
in Figure 1 and 2.
Figure 1 shows the amount of oat seed that was collected from the weedy plots. The varieties’ ability
to reduce the seed set of weeds varied markedly with Compass, Maritime and Fathom being the best
in the 2013 trial. Weed seed set was much higher in the Hindmarsh, GrangeR and Gairdner plots. This
is partly due to a variety of factors including a more erect growing pattern style and a reduced early
vigour.
www.msfp.org.au
34
Gairdner
Hindmarsh
GrangeR
Scope
Wimmera
Commander
Skipper
Fleet
Fathom
Maritime
Compass
Site mean % oat yied
160
140
120
100
80
60
40
20
0
Variety
Figure 1. Yield of oats (as a percentage of the site mean) collected from each barley treatment. Oats
were sown prior to barley to simulate weeds.
Hindmarsh
GrangeR
Commander
Gairdner
Wimmera
Fleet
Compass
Maritime
Skipper
Scope
40.0
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
Fathom
Percentage loss
Figure 2 illustrates the difference in yield between varieties when placed under weed pressure
compared to no weed pressure. These results show a similar trend to those in Figure 1 where varieties
with a higher early vigour and denser canopy competed better with the weeds.
Figure 2. The percentage yield difference between the weed free plots and the plots with weeds. Oats
were sown prior to barley to simulate weeds.
Further Information
Simon Goss
Research Agronomist – Barley And Durum
New Variety Agronomy
Email: [email protected]
Mobile: 0408 464 795
www.msfp.org.au
35
Current and New Barley Varieties
Stewart Coventry and Jason Eglinton, University of Adelaide
Take Home Messages
• Commander is an internationally accepted malting barley
• Fleet and Fathom are Mallee adapted high yielding feed varieties
• Compass and La Trobe are the new high yielding potential malting varieties to watch
• 2013 results highlight varietal differences in grain size
The current barley variety mix
The trends in variety adoption seen over the past few years continued in 2013 with Hindmarsh,
Commander, Fleet and Buloke firmly established as the dominant varieties. Hindmarsh had
proportionally less production in the SA Mallee than in other areas due to other feed varieties such as
Fleet and Fathom having more tolerance to fungicide amended seed treatments and pre-emergent
herbicides, weed competition and better establishment through a longer coleoptile length, improved
vigour and height. A number of newer varieties have achieved malting accreditation however of these
only Scope will be segregated in the Mallee. Preliminary segregation plans in the SA and Victorian
Mallee indicate Commander, Scope and Hindmarsh will be the preferred segregated varieties. Until
international markets have been fully developed for Scope, it is likely to achieve only a modest
premium, and is currently priced the same as Hindmarsh, just above Feed 1. The imidazolinone
tolerance of Scope has application as a management tool for paddocks with high weed burden or
suspected imidazolinone residues. Although Scope is an imi-tolerant version of Buloke it cannot be cobinned as the malting barley industry purchases varieties based on their purity. Commander has both
domestic and international market acceptance, attracting a premium. Commander is the current
benchmark malting barley combining high yield and large grain size to achieving the highest frequency
of malt 1 at receival.
In the Mallee, the 2013 site average was 2.3t/ha which is similar to the long term average reflecting
the dry spring conditions. Winter conditions were favourable for development of both spot and net
forms of net blotch which were the most prevalent diseases. For spot form net blotch it is only
important to consider a fungicide treatment for very susceptible varieties in stubbles likely to carry a
high inoculum load.
In the Mallee, the feed varieties Fathom and Fleet were the best performers for yield and had excellent
grain size. Hindmarsh was also a top performer in the Victorian Mallee and has a proven track record
in reliably meeting Feed 1 screenings levels but with increasing opportunities to market Hindmarsh
above the feed grades it is timely to consider retention values in comparison to other malting options
as shown in Table 1. In areas with heavy pressure on grain size the plumpness values for Hindmarsh
are generally lower than Commander, reducing its probability of achieving premium prices. Although
now an older variety, Keel also featured in the top list within SA Mallee sites, where it’s very early
maturity was an advantage under very dry spring conditions.
www.msfp.org.au
36
Of the malting varieties, Commander has been yielding equivalent to the highest feed variety Fleet in
the SA Mallee long term data, though last year fell back to the yield of Hindmarsh. In the Victorian
Mallee the yield, of Commander tends to drop below Hindmarsh, but the retention values of
Commander to make Malt 1 grade tends to be better. Commander was higher yielding than Buloke
and Scope in the Mallee based on its long term yield performance, and has been the better option
particularly since Buloke and Scope have inferior grain size albeit with slightly higher test weights.
Buloke and Scope were often below the 70% retention limit for malt1 while Commander was
significantly better. Until the new potential malt varieties are accredited, Commander’s yield and grain
characteristics will ensure that it is one of the most profitable varieties to grow with a greater likelyhood of achieving malt grain quality.
New potential malting varieties
Of the next generation of barley varieties undergoing malting accreditation (Table 1), Compass, La
Trobe, and Skipper are likely to be most relevant to the Mallee. Both La Trobe and Skipper have
expected accreditation dates of 2015 and Compass in 2016. There will be retail seed availability for
Compass and La Trobe in 2015 to be delivered as feed until malt accredited. It should be noted that
there may be some lag between the year a variety is malt accredited and when variety segregations
are offered since domestic and international market development and acceptance is needed.
Compass
Compass, which has now been tested for two seasons in National Variety Trials (NVT), produced
consistent and very high yields in all districts. In the long term and 2013 Mallee NVT yield analysis,
Compass is the highest yielding variety even against other feed varieties. This represents the next step
change in yield and grain size. Compass offers an agronomic package similar to Commander with much
improved yield and disease resistance. Compass has good resistance to CCN, net form net blotch,
powdery mildew and root lesion nematode. It produces very plump grain with good retention and low
screenings but moderate test weight like Commander and susceptibility to black point like Buloke and
Schooner. Irrespective of its final malt status, Compass will be a very profitable variety to grow.
La Trobe
La Trobe performed well across all regions in 2013 showing yields generally similar or slightly higher
than Hindmarsh. La Trobe is derived from Hindmarsh with similar wide adaptation but like Hindmarsh
is less suited to sandy Mallee soils, reflected in the SA Mallee yield results. La Trobe has a similar
disease resistance profile as Hindmarsh but is more resistant to root lesion nematode and more
susceptible to leaf rust. La Trobe has a short coleoptile, like Hindmarsh, good test weight but moderate
plumpness and screenings.
Skipper
Data from NVT in SA since 2009 has shown Skipper to yield similarly to Commander and would be a
useful alternative in the lower rainfall environments. It is early maturing with good early vigour, weed
competitiveness and grainsize. Skipper has strong resistance to both forms of net blotch, powdery
mildew and Cereal Cyst Nematode (CCN)but is susceptible to some strains of leaf rust and leaf scald.
It has very plump grain with improved test weight, retention and protein relative to Commander.
www.msfp.org.au
37
Table 1: Barley NVT data of long term (2008-2013) and 2013 SA and Victorian Mallee Grain yield and
2013 SA and Victorian Mallee Retention values. Varieties in bold underline have the highest grain
yield or retention.
FEED
Fathom
Fleet
Keel
Maritime
Oxford
MALTING / FOOD*
Bass
Buloke
Commander
Flagship
GrangeR
Hindmarsh*
Schooner
Scope
Sloop SA
UNDERGOING
ACCREDITATION
Compass
Flinders
La Trobe
Skipper
Regional Mean
Yield (t/ha)
2008-2013 SA
Murray Mallee
Grain Yield
(% site mean)
2013 SA
Murray Mallee
Grain Yield
(% site mean)
2013 SA
Murray Mallee
Retention
(% site mean)
2008-2013 VIC
Mallee
Grain Yield
(% site mean)
2013 Vic
Mallee
Grain Yield
(% site mean)
2013 Vic
Mallee
Retention
(% site mean)
109
114
99
101
109
108
112
110
94
99
91
87
89
93
59
114
112
110
102
104
111
105
108
91
92
90
90
84
97
66
93
106
112
103
108
105
92
109
100
87
96
104
107
101
104
84
99
93
88
70
83
78
82
82
76
76
81
102
106
109
100
103
114
95
104
100
99
103
101
97
94
107
93
101
91
94
81
89
82
79
86
86
83
89
116
101
108
107
115
96
102
104
93
79
78
91
119
101
115
111
113
92
108
99
94
87
85
89
2.16
2.34
2.46
2.30
Compass and Skipper are bred by the University of Adelaide Barley Program and seed is available
through Seednet. La Trobe and Flinders are bred by Intergrain Pty. Ltd and seed is available through
Syngenta Australia.
Further information
Stewart Coventry, University of Adelaide Barley Program
[email protected], 83136531
www.msfp.org.au
38
Vetch: More than just fodder
Stuart Nagel, Gregg Kirby and Rade Matic, SARDI, National Vetch Breeding Program
Take Home Message:
•
Vetch is versatile in terms of its potential end uses – grain, hay/silage, pasture or green/brown
manure.
• It is well adapted to no-till, standing stubble systems aimed at improving soil sustainability
• Provides an opportunity to control grass weeds: Hay can be cut before many grasses set seed
and green/brown manuring can also be used to control competitive weeds which are difficult
to control in other crops, e.g. brome grass and barley grass.
• Research has shown soil nitrogen levels improved by an average of 56, 92 and 145kg/ha after
grain, hay and green manuring, respectively.
• Grain and hay/silage from common vetch varieties can be used to feed ruminants without
limitations
The Versatility of vetch
A vetch crop has the ability to offer substantial improvements in soil fertility, structure and organic
matter as well as offering a weed and disease break for cereals in a crop rotation. The National Vetch
Breeding Program results have shown, across five sites over three years, after a vetch grain crop total
nitrogen in the soil increased by 56kg/ha. From two sites over two years after hay production there
was 94kg/ha of nitrogen returned to the soil and 154 kg per ha after green manuring.
During the season vetch producers can choose the best end use option for their crop. If the season is
not finishing well and the crop may have insufficient water to produce good seed, then it can be better
to cut the crop for hay, or take the opportunity to use it as green or brown manure. This can prove
more beneficial in the long term than keeping an underperforming grain crop as it offers the
opportunity to control herbicide resistant grass weeds before they set seed.
Apart from the benefits vetch can provide in the rotation, vetch grain, hay and silage is a valuable
source of crude protein, metabolisable energy with high dry matter digestibility for livestock (Table 3).
Grain from common vetches can be used without limitations for feeding ruminants. Vetch hay is also
extremely palatable with high levels of crude protein and metabolisable energy, good leaf retention
and little wastage by animals. Vetch included in a pasture or replacing fallow in a rotation can increase
a paddock’s feeding value and number of livestock carried per hectare.
The National Vetch Breeding Program has released four common vetch varieties (see Tables 1-4 for
yield, quality and agronomic traits) and all are highly resistant to rust and lower in grain toxin (<0.65%)
than the old varieties Blanchefleur and Languedoc which contain 0.98%, 1.42% grain toxin
respectively.
New research
In 2014 The National Vetch Breeding Program commenced a South Australian Grains Industry Trust
(SAGIT) funded project that is investigating the potential of vetch (common vetch) to provide a
genuine legume break crop option for cereal and mixed farmers in the marginal cropping areas of
South Australia. Focusing on Western Eyre Peninsular, the Upper North and the Mallee regions, the
sites are located at Morchard, Minnipa and Karoonda.
www.msfp.org.au
39
This project is trialing advanced common vetch lines bred in previous GRDC projects with specific
targeted traits for lower rainfall areas such as:
• good early vigour and establishment
• cold tolerance and winter growth
• early maturity with good biomass production
• high palatability, as both green and dry fodder
• good seed production
• soft seeds/high germination rates and
• Tolerance/resistance to rust.
Agronomic performance of vetch varieties
Table 1: 2008-2012 Vetch grain yields in low rainfall areas
Low-mid rainfall areas (330-380mm/yr)
VARIETY
Blyth, Lameroo & Peake
Mean (t/ha)
% of Rasina
Morava
1.89
81
Rasina
2.32
100
Blanchefleur
1.88
81
Volga
2.87
124
Timok
2.44
105
Table 2: 2008-2012 Dry matter production
of vetch varieties in low rainfall areas
Low-mid rainfall (330-380mm/yr)
VARIETY
Blyth & Lameroo
Mean (t/ha) % of Morava
Morava
3.25
100
Rasina
3.28
101
3.56
3.86
Volga
Timok
Table 3.Quality measurements of common vetch grain and hay
End use
Crude Protein (%)
Metab. Energy (MJ/kg DM)
Hay
21.5
10.2
Grain
29.78
12.8
110
119
Dry Matter Digestibility (%)
84.3
85.7
Table 4. Agronomic traits and recommendations for vetch production and end use
Vigor at
flowering
Variety
Yield potential* & end-use by rainfall zones
Days: Seeding to full
<350
350-450
>450
Pod
Flower
Shatter.
colour
flowering
Grain
Forage
Grain
Forage
Grain
Forage
(%)
Blanchefleur
Moderate
95-105






20-25
White
Morava
V. good
115-130






0-2
Purple
Rasina
Moderate
95-105






3-5
Purple
Volga
Good
90-100






0-2
Purple
Timok
V. good
100-110






0-2
Purple
* = Not suitable,  = Moderate yield,  = high yield
www.msfp.org.au
40
Acknowledgement
The National Vetch Breeding Program would like to thank South Australian Grains Industry Trust,
Grains Research & Development Corporation, Rural Industries Research & Development Corporation
and South Australian Research & Development Institute for funding this program and acknowledge
the ongoing support and interest provided by Australian farmers. Farmers and not for profit farmer
groups and organisations provide trial sites, feedback, advice, recommendations and their wish lists
for future varieties to the program, all of which are gratefully received and appreciated.
Further information
Rade Matic, SARDI, Waite
E-mail: [email protected]
Ph. 0408 826 550
Stuart Nagel, SARDI, Waite
E-mail: [email protected]
Ph. 0407 720 729
Gregg Kirby, SARDI, Waite
E-mail: [email protected]
Ph. 0401 122 193
Upcoming MSF Events to Keep an eye out for!
Kyalite (NSW) – 2nd Last Week in September 2014 Date TBC
Ouyen (VIC) – Friday 3rd October 2014 Date TBC
Keep updated on our events by going to http://msfp.org.au/events/
You can also keep up to date with MSF by liking our Facebook Page:
www.facebook.com/MalleeSustainableFarming
MSF also has some new videos on our YouTube channel, this includes GO pro footage of different seeder
setups in action, as well as a couple of videos about utilising perennials such as saltbush to improve
productivity on constrained soils in the Mallee.
https://www.youtube.com/MSFMildura
www.msfp.org.au
41
Maximising the Nitrogen benefits of rhizobial inoculation
Maarten Ryder1, Matt Denton1 and Ross Ballard2
1
School of Agriculture, Food and Wine, the University of Adelaide 2SARDI, Waite Campus, Urrbrae SA
Take Home Messages
• Inoculation of legumes with rhizobia can deliver substantial nitrogen (N) inputs to southern
farming systems even when the impact on legume yield is small.
• When inoculating, CARE needs to be taken in situations where the survival of rhizobia is
compromised, such as dry sowing, acid soils, mixing rhizobia with fertilisers and pesticides: follow
the guidelines.
• In late winter or early spring, digging up legumes to check on nodulation success will help with
planning inoculation in future seasons and troubleshooting.
• To maximise the chances of getting a positive response to inoculation, follow the guidelines that
are set out in several recent Grains Research and Development Corporation (GRDC) publications.
Introduction
Inoculation of legumes with rhizobia is a standard practice but we can optimise legume nodulation
and improve nitrogen inputs by following a few basic rules of thumb and by fine-tuning inoculation
practices.
Inoculation can greatly increase the amount of biologically fixed N from legumes where they are sown
for the first time or where soils are not conducive to rhizobial survival. For example, inoculation of
faba bean in south western Victoria boosted fixed N from 32 to 196 kg N/ha, as well as increasing dry
matter production and increasing yield by 1 tonne/ha compared with an uninoculated crop*. It is also
common for growers to get fixed N benefits from inoculation even when the inoculation only leads to
a small yield increase.
You have probably heard the phrases “if in doubt, inoculate” and “inoculation is cheap insurance” as
well as the message to “inoculate every year”. These messages are sometimes appropriate but may
lead to unnecessary inoculation in some instances or alternatively cause growers to become cynical
about the need for inoculation, which can result in the sub-optimal use of inoculant.
After making the decision to inoculate, it is worth maximising the chances of success, as inoculation
failure is generally difficult and expensive to remedy. Following some general guidelines will be
helpful, to ensure successful legume nodulation, noting that there is a range of inoculant products
available, with different application methods.
Changing practices on farm, such as the trend towards early (dry) sowing in some regions, is taking us
into new territory with respect to recommendations about rhizobial inoculation. Another important
and common practical issue is the degree of compatibility between rhizobial inoculant and fertilizers
and seed-applied pesticides and additives. Although it would be useful to know the compatibility of
each rhizobial strain with all of the common chemical formulations, only limited information is
currently available.
* Denton MD, Pearce DJ, Peoples MB (2013) Plant and Soil 365, 363-374.
www.msfp.org.au
42
When, where and how to inoculate?
If the legume (or another that uses the same rhizobia) has not been grown in the last four years, or
soil conditions are hostile then the chance of getting a good response to inoculation is high. There is
a low likelihood of response to inoculating grain legume crops or pastures where there has been a
recent history of inoculation with the correct rhizobia (i.e. the right inoculant group), the soil pH is
above 6 (in CaCl2), and recent nodulation, grain yields and pasture production have been good. In
these situations, inoculation every four years or so will be adequate because soil rhizobial populations
will generally be maintained at above 1,000 per gram, which is considered adequate for good
nodulation.
Where acid-sensitive legumes (eg peas and beans) are sown into acid soils (pH 5.5 or less in CaCl2), it
is a good idea to inoculate every time a crop is sown because rhizobial populations tend to diminish
quickly under these soil conditions. The exception to this acid soil rule is lupin, because both lupin
and its rhizobial strain are well-adapted to acid soils.
Where a crop such as chickpea, which has a very specific rhizobia requirement, is grown for the first
time, inoculation is essential as there will be no background of suitable rhizobia present. A double
rate of inoculant is often used in these situations, to enhance the likelihood of good nodulation.
Common inoculation issues faced by legume growers
Can I sow inoculated seed into dry soil?
Sowing inoculated seed into dry soil is not recommended where a legume crop is sown for the first
time. On the other hand, where a legume has been used frequently and the soil is not particularly
hostile to rhizobia, the risk of nodulation failure resulting from dry sowing is very much reduced.
Granular formulations which are applied in furrow are placed deeper in the soil and will have a better
chance of survival, as soil conditions will be less extreme at greater depth.
Can I mix inoculated seed with fertilizer, including trace elements?
Some growers claim success in mixing rhizobial inoculant with fertiliser and/or trace elements.
Rhizobium biologists recommend against mixing inoculant with fertilisers (particularly
superphosphate and others that are very acidic), acidic formulations of trace elements or novel plant
nutrition treatments. However we recognise that farming operations need to be practical and
economic. Small scale testing is highly recommended where mixing inoculum with fertilisers and
micro-nutrients is contemplated. Tanks should be cleaned well before they are used for rhizobial
inoculum. Placement of the fertiliser or trace elements away from the rhizobial inoculum (e.g. in
furrow below the seed) is highly recommended. It is worth noting that the detrimental effects of
mixing inoculants and fertilisers etc. are often overlooked because legumes are often sown in
paddocks that are not responsive to inoculation. It is only when a nodulation problem suddenly
appears in a paddock that should be responsive to inoculation, that the harmful effect of mixing
rhizobia with other products can become very clear.
If molybdenum is required as a seed treatment (Mo is sometimes needed for optimum nodulation,
especially in acid soils), then molybdenum trioxide or ammonium molybdate should be used, NOT
sodium molybdate (toxic to rhizobia!).
Can I mix rhizobial inoculant with seed pickles and pesticides?
Some combinations of rhizobia with some pickles and pesticides appear to perform satisfactorily,
whereas others are very effective at destroying rhizobia. The GRDC booklet “Inoculating Legumes: a
practical guide” contains a table (p. 40) that lists the compatibility of different rhizobia groups with
seed-applied fungicides, and also discusses specific compatibility issues between rhizobia and certain
www.msfp.org.au
43
insecticides and herbicides. Pickled seed can be coated with rhizobia (except soybean and peanut)
but the time interval between inoculation and sowing should be kept to a minimum, usually less than
six hours. The use of granular inoculants or liquid inoculation into furrows can reduce this impact by
separating the pickled seed from the inoculant.
The following mixtures are NOT compatible with peat, liquid and freeze-dried inoculants:
• chemicals containing high levels of zinc, copper or mercury;
• fertilisers and seed dressings containing sodium molybdate, zinc and manganese;
• fungicides such as Sumisclex® or Rovral®
• herbicides such as MCPA, 2,4-D and Dinoseb;
• insecticides containing endosulfan, dimethoate, omethoate, or carbofuran
Checking for nodulation success
In recent GRDC publications about rhizobial inoculation, ‘good nodulation’ and ‘well-nodulated crops’
are frequently referred to and guidelines are given about adequate numbers of nodules per plant.
How do we go about checking this? We strongly encourage growers and consultants to look below
the soil surface: dig up several plants about 2 to 3 months after sowing, wash out the root systems
gently and look at the level of nodulation on the roots.
A visual check of root systems is worthwhile, to see if a reasonable number of nodules is present and
if they are well distributed across the root system or whether there has been a nodulation delay or
failure. Carefully breaking open nodules to determine if there is a pink or reddish colour in the nodules
will show that the nodules are active. Neither of these visual assessments however will give an
indication of the actual level of N fixation being achieved: sophisticated scientific techniques are
required to measure this.
Checking nodulation success will help to decide about the need for inoculation in future years. A guide
to
assessing
nodulation
in
pulse
crops
is
provided
at
www.agwine.adelaide.edu.au/research/farming/legumes-nitrogen/legume-inoculation/.
Several recent GRDC publications give useful information about optimising inoculation and nitrogen
inputs from N fixation. These publications are available online or from the GRDC, or through
http://www.agwine.adelaide.edu.au/research/farming/legumes-nitrogen/legume-inoculation/.
Further reading
“Inoculating Legumes: a practical guide” (GRDC 2012) Free, online
http://www.grdc.com.au/GRDC-Booklet-InoculatingLegumes
“Inoculating Legumes: The Back Pocket Guide” (GRDC 2013) Free, online
http://www.grdc.com.au/Resources/Publications/2013/09/Inoculating-legumes-back-pocket-guide
“Fact Sheet: Rhizobial inoculants” (GRDC 2013) Free, online
http://www.grdc.com.au/~/media/B943F697AF9A406ABBA20E136FDB7DC4.pdf
Further information
Maarten Ryder, University of Adelaide
[email protected]
Tel 0409 696 360
www.msfp.org.au
44
Wheat seed source and seed size effects on grain yield
Shafiya Hussein and Glenn McDonald, SARDI & University of Adelaide
Take Home Messages
• In 2013 high yields were associated with seed with high phosphorus and potassium content.
• The source of seed can influence seed nutrient content
• Large seed size increased early vegetative growth in 2013 and 2014 but the yield response in 2013
varied between sites.
• In 2013 Emu Rock, a larger seed out yielded Mace, Scout and Estoc.
• Large seeded varieties like Emu Rock and Corack also have high plant establishment and
vegetative growth.
Why do the trial?
It is advantageous to have good quality seed of high genetic purity, physical quality and nutrient
content. Two important determinants of seed quality are seed size and seed nutrient content. Larger
seed size has a bigger germ and generally more available nutrients. Source of seed can also be
important because soil type, fertiliser applications and season can affect seed nutrient content. High
quality seed will often germinate more quickly and evenly, show greater seedling vigour and can result
in higher yields than seed of lower quality. This trial was conducted to examine the influence of seed
size and seed source on wheat growth and yield.
How was it done?
In 2013 four wheat varieties (Emu Rock, Estoc, Mace and Scout) were selected from National Variety
Trials (NVT) at Nangari, Nunjikompita, Penong, Turretfield and Wanbi which produced seed of
different nutrient concentrations (Table 1). The seed was sieved into large (>2.8mm) and medium size
(2.5-2.8mm) fractions and sown at Karoonda, Minnipa and Turretfield. The trial was repeated in 2014
with Corack, Emu Rock and Mace using large (>2.8mm), medium size (2.5-2.8mm) and small (2.22.5mm) seed fractions. The trials were sown at 150 plants/m2 in plots 5m x 6 rows (9.5 inch row
spacing). Fertiliser (DAP + 2% Zn at 98kg/ha) was applied at sowing. The trial was assessed for plant
establishment, early vigour (assessed as Normalised Differential Vegetation Index (NDVI) using a
Greenseeker), grain yield and grain quality.
What happened?
Seed nutrient concentrations
There were consistent differences in seed nutrient contents in 2012 and 2013. Seed from Nangari and
Nunjikompita had the lowest phosphorus and potassium concentrations while seed from Turretfield
had the highest. Nangari seed also had low zinc concentrations. The concentrations of phosphorus
and potassium were highly correlated.
Vegetative growth in 2013 and 2014.
The larger seed improved germination by 6-9% and increased vegetative growth at early stem
elongation at Turretfield and Minnipa in 2013. In 2014 larger seed has also promoted early vegetative
growth and the effect was most evident in Corack (Figure 1).
www.msfp.org.au
45
Table 1. Seed nutrient concentration for Mace from NVT trials at four sites in SA in 2012 and 2013.
Seed source
Thousand
grain wt (g)
__________
2012 2013
GPC (%)
__________
2012 2013
P
(mg/kg)
__________
2012 2013
K
(mg/kg)
__________
2012 2013
Zn
(mg/kg)
__________
2012 2013
Mn
(mg/kg)
__________
2012 2013
Nangari
39.1
36.3
9.7
10.4
1600
1990
3300
3300
9
11
31
38
Nunjikompit
a
Turretfield
32.1
32.6
12.6
11.5
1780
2200
3500
3600
20
20
38
46
35.4
27.9
10.1
13.4
3200
4000
4600
4900
20
21
46
43
Wanbi
38.9
38.4
11.7
13.5
2700
3400
3800
4400
20
21
31
43
Grain yield and grain quality in 2013
Seed source significantly affected grain yield in 2013 and the variation in grain yield were most closely
related to the concentrations of phosphorus and potassium in the grain (Figure 2). The effect of seed
size varied with the site: larger seed size increased yield at Turretfield by 4%, had no effect at Minnipa
and resulted in a 3% lower yield at Karoonda (Table 2). Grain quality was not significantly affected by
seed source or seed size. Emu Rock and Mace yielded significantly higher than Estoc and Scout at all
sites (Figure 3).
Table 2. Effect of seed size on yield of wheat at three sites.
Site
Seed size
2.5-2.8mm
Karoonda
Minnipa
Turretfield
1839
2893
3358
Probability
>2.8mm
(kg/ha)
1783
2885
3502
P=0.007
ns
P=0.034
Figure 1: Average vegetative growth (NDVI) of Corack, Emu Rock and Mace between June 16th and
July 30th for seed graded into three sizes at Karoonda 2014.
www.msfp.org.au
46
Figure 2. The relationships between the average phosphorus (P) and potassium (K) concentration
of grain from different sources and the grain yield at Minnipa in 2013. Each point is the average of
four varieties.
Figure 3: A comparison of grain yield and wheat varieties at Karoonda (Mallee), Minnipa (Upper
Eyre Peninsula) and Turretfield (Mid North) in 2013
What does this mean?
• Seed source influenced yield of wheat through its effect on seed nutrient content.
• Seed phosphorus and potassium appear to be important in affecting establishment, crop
vigour and yield.
• Using seed with low phosphorus and potassium concentrations can reduce early vigour and
yield.
• The importance of seed size appears to depend on the site and may be more beneficial in
higher yielding environments.
• Mace and Emu Rock have consistently yielded higher than Estoc and Scout at all three sites in
2013.
Acknowledgement
We would like to thank South Australian Grains Industry Trust (SAGIT) for funding this project. Thanks
to Charlton Jeisman and Paul Swain for sowing trial and Simon Goss for helping with field assessments.
Further information
Dr Glenn McDonald, University of Adelaide
[email protected]
83135378
www.msfp.org.au
Shafiya Hussein, SARDI, Waite Campus
[email protected]
0407766058
47
Head on over to the Mallee Sustainable Farming website for
further information on the topics here today.
www.msfp.org.au
www.msfp.org.au
48