Net water benefit of cover crops in Northern grains production. Farming water with ground cover

Andrew Erbacher1, David Lawrence2, David Freebairn3, Neil Huth4, Brook Anderson4 & Graham Harris2

 1 Department of Agriculture and Fisheries, 22-26 Lagoon St, Goondiwindi, Qld, 4390,

2 Department of Agriculture and Fisheries, 203 Tor St, Toowoomba, Qld, 4350.

3 DM Freebairn, Wilston, Qld, 4051

4 CSIRO, 203 Tor St, Toowoomba, Qld, 4350.


Low groundcover increases risk of soil erosion and reduces fallow efficiency. To remedy this cover crops can be grown to increase groundcover, but does the increased ground cover improve fallow water accumulation enough to recover the water used to grow the cover crop? To answer this, cover crops were planted into a long fallow following skip row sorghum, and sprayed out prior to growing wheat. The main cover crop was White French millet, which had different termination timings imposed. Other crops included sorghum, lablab and a mixed species (millet, lablab and tillage radish), which were all sprayed out at the same time as the mid-terminated millet. By planting of the subsequent wheat crop, all cover crop treatments, except the lablab, had recovered the water they used prior to termination, with some accumulating more plant available water (PAW) than the control. Increased ground-cover improved establishment of the wheat and all cover crop treatments had higher grain yield than the bare control in a drier than average season. These results confirm a crop can be grown and sprayed out to improve ground cover in a long fallow, without having a net negative effect on PAW, with yield benefits in the following crop in excess of what can be explained by increased soil water.

Deep soil water-use determines the yield benefit of long cycle wheat

BM Flohr1, JR Hunt2, JA Kirkegaard3, B Rheinheimer3, T Swan3, L Goward3, JR Evans4, M Bullock3

 1CSIRO Agriculture and Food, Adelaide, South Australia, Australia,

2Department of Animal, Plant and Soil Sciences, AgriBio Centre for AgriBiosciences, La Trobe University, Melbourne, Victoria, Australia

3 CSIRO Agriculture and Food, Canberra, Australian Capital Territory, Australia

4 The Australian National University, Research School of Biology, Canberra, ACT 2601, Australia


The yield advantage of early sown slow developing (long cycle) wheat cultivars over fast developing cultivars sown later (short cycle) is variable. This variable response is likely due to environmental factors, but the precise set of conditions that confers an advantage to long cycle treatments is not known. We compared short and long cycle wheat cultivar x time of sowing combinations over four seasons in Temora, NSW. Two seasons (2011, 2012) had over 400 mm of summer fallow (December-April) rain which filled the soil profile to depth, and two seasons had summer fallow rain that was less than the site average of 208 mm (2015, 2016). Rainfall 30 days prior to the start of flowering (approximating the critical period for yield determination) in each year was 8, 6, 14, 190 mm respectively. We observed that there was only a yield benefit in long cycle treatments in seasons where there was soil water stored at depth, and there was little rain during the critical period for yield determination in wheat, forcing greater reliance on stored soil water for crop growth (2011, 2012). In these seasons the higher yield of long cycle treatments could be attributed to greater soil water extraction from deep in the profile (<1.0 m), and consequently greater dry-matter production, grain number and grain yield. In the other seasons, lower evaporation and higher biomass accumulation in long cycle treatments traded off against inferior harvest index such that yields were equivalent to short cycle treatments.

Crop simulation for farming systems: from phenotype to farm

Julianne Lilley

CSIRO Agriculture and Food, GPO Box 1700, Canberra ACT 2601, Australia


The value of simulation models to assist (i) crop breeding, (ii) agronomic research, and (iii) farm decision-making has been demonstrated in many studies (Holzworth et al. 2014; van Ittersum and Donatelli 2003). In the Australian grains industry several modelling platforms have been developed for a variety of needs, with APSIM (Agricultural Production Systems Simulator) the predominant tool (Robertson et al. 2015). APSIM allows models of crop and pasture production, residue decomposition, soil water and nutrient flow, and erosion to be configured to simulate soil and crop management for various production systems using conditional rules (Holzworth et al. 2014). The model has been well validated in many studies and shown to accurately capture the effects of variability in climate, soil type and management for a range of crops. Linking of APSIM and GRAZPLAN farming systems models (Moore et al. 2007) has also enabled assessment of whole farm issues associated with crop and animal production as well as environmental impacts of a range of practices on mixed farms (Lilley and Moore 2009, Robertson et al. 2009).

In this paper I discuss application of the APSIM model at three scales; (i) the value of individual genetic traits within the context of the farming system, (ii) single or multiple changes to management practices for individual crops over multiple years and locations, and (iii) the effect of a management or genotype change, in the context of multi-year sequences, or multiple paddocks across the whole farm. Case studies at each scale will demonstrate the value of simulation modelling as an integrated tool in modern farming systems research.

Risks and rewards of growing pulse crops in the low rainfall Mallee cropping region

Michael Moodie1, Todd McDonald1, Nigel Wilhelm2, and Ray Correll3

1 Frontier Farming Systems, 7B Byrne Ct, Mildura, Victoria, 3500,,

2South Australian Research & Development Institute, PO Box 397, Adelaide, South Australia 5001

3RHO Environmetrics, PO 366 Highgate, SA, 5064


The adoption of pulse crops in low rainfall cropping regions such as the Mallee is increasing.  While the farming system benefits of pulse crops are clear, there is a lack of regionally available data to support grower decisions on the most profitable pulse crops to select.  Over three contrasting seasons, we directly compared pulse crop productivity on four regionally important soil types in the South Australian Mallee.  Overall, most pulse crops had similar productivity potential but the yields were highly influenced by seasonal conditions and soil type.  Season had the greatest impact on productivity with yields almost four times more in a high rainfall (decile 8-10) year than in a low (decile 2-4) rainfall season.  Pulse crop yields also varied by up to 60 percent between soil types.  The highest and least variable grain yields were achieved on the sandy loam – loam soil types, with lower productivity and high yield variability obtained on both the heavy and sandy soils.  Subsequent Monte Carlo simulation using @Risk quantified the risk and reward profile of each crop for Mallee farming systems.  The analysis showed that lentils had both the greatest profit potential and lowest financial risk of all pulse crops over the long term.  Vetch, chickpea and field pea are expected to generate long term gross margins of more than $200/ha.  Chickpea and field pea are expected to have a negative gross margin in more than 30% of years but a high gross margin (>$500/ha) is expected in nearly one in five seasons.  This information will allow Mallee growers to make more informed selections of the most appropriate pulse crops for their farming system.

Frontiers of farm productivity: using more of the soil and more of the season

John Kirkegaard, Julianne Lilley

CSIRO Agriculture and Food, GPO Box 1700, Canberra ACT 2614,,


Integrating long-season wheat and canola crops in a crop sequence can significantly increase farm productivity and profitability through higher yield potential, improved timing of the whole-farm sowing program, and through grazing. However deep soil water use of higher-yielding crops can leave a legacy of dry or N-depleted soil that may impact subsequent crops, and reduce the expected yield benefits across the crop sequence. We used the APSIM model, validated against 30 years of measured data from a long-term field experiment at Harden in NSW to explore the legacy effects and overall impact of incorporating long-season wheat and canola crops into the cropping system at Harden in southern NSW. APSIM predicted dynamics of water, mineral N, biomass and yield adequately across the continuous 30-year sequence, providing confidence in the ability to explore modified management scenarios. At Harden, we predicted opportunities to increase mean wheat yield (22%) and canola yield (14%) using early-sown, long-season varieties compared to faster-maturing spring varieties sown in May, in seasons where early sowing (from March 1) was possible. The yield improvements increased to 33% for wheat and 72% for canola when an extra 50 kg N/ha was top-dressed each season demonstrating the importance of matching N supply to the higher yield potential of the crops. The continuous simulation revealed legacy effects were evident in some seasons, but were small overall, at least in this high rainfall environment. The approach can be applied elsewhere, but relies on well-validated, continuous simulation of the crop sequence, which are rare.

Yield benefits of fallow to high value crops

Katherine Dunsford1, James Nuttall1, Roger Armstrong1 and Garry O’Leary1

1 Agriculture Victoria, 110 Natimuk Road, Horsham, Victoria, 3400,


Recently, there has been renewed interest in long (18-month) fallowing as a means of managing risk in Australian dryland cropping systems. Traditionally, wheat was grown after long fallows, however, given the high commodity value and rotational benefits of crops such as canola and pulses, the contribution of long fallow to additional yield potential warrants exploration. We used a crop simulation modelling approach to assess the yield benefits of growing canola (Brassica napus), lentil (Lens culinaris) and wheat (Triticum aestivum) after either an 18-month fallow or wheat crop (i.e. 6-month fallow) using initialisation data from a long-term rotation experiment (Sustainable Crop Rotations In Mediterranean Environments; SCRIME) in the Wimmera region of Victoria. Secondly, we simulated a three-phase rotation to see whether the benefits of fallow would persist beyond the first season. Long fallowing provided large yield benefits to wheat (17%) and canola (14%) and to a lesser extent in lentils. Additional soil water was observed (31 mm) after fallow/lentil. The soil water and nitrogen benefits of the fallow/lentil rotation persisted to third phase wheat crop and increased yield. On average, however, continuous cropping including a pulse crop (i.e. wheat/lentil/wheat) yielded more but was subject to greater risk of crop failure. Consequently, given the high value of canola and lentil, it is worth considering the benefit of using a long fallow ahead of these crops to maximise yield potential and stability. Next steps include assessing the net economic benefit of these proposed rotations, where long fallow equates to lost income in that year.


Drivers of system water use efficiency in cropping systems of Australia’s northern grains zone

Lindsay W Bell 1, Andrew Zull2, Darren Aisthorpe2, David Lawrence2, Andrew Verrell3, Jon Baird3, Andrew Erbacher2, Jayne Gentry2, Greg Brooke3 and Kaara Klepper4

1 CSIRO Agriculture and Food, Toowoomba Qld 4350,

2 Department of Agriculture and Fisheries, Queensland

3 New South Wales Department of Primary Industries



Farming systems experiments were undertaken across multiple sites spanning Australia’s northern grains region. A regional baseline of local current best practice was compared with several cropping system strategies that varied in cropping intensity (i.e. number of crops sown/yr), crop choices and nutrient application strategy. Crop yields, inputs and soil water dynamics were monitored in each system over 3.5 years to calculate the system water use efficiency (WUEsystem), i.e. the $ gross margin per mm of system water use (rainfall + change in soil water). Large gaps in profitability were found between the best and worst systems at each site ($200-700 per year between systems). Increasing crop intensity increased costs and either reduced or equalled the system water use efficiency (WUE) compared to the baseline systems at most sites. A promising lever to enhance farming system profitability is therefore, adjusting crop intensity to environmental potential. Increasing grain legume frequency achieved similar profitability and system WUE as the baseline. Increasing crop diversity and growing alternative crops increased costs but also profitability at some sites by managing diseases or weeds. Increasing nutrient supply incurred higher costs and as yet has rarely increased system profitability. Additional nutrients only increased system WUE when one crop in the sequence experienced > median rainfall (i.e. Trangie & Emerald).

Future climate change increases canola productivity and water use efficiency in the rainfed cropping systems of Southern Australia

Hongtao Xing, Rohan Brill, Guangdi Li, De Li Liu, Allison Blake, Deb Slinger

NSW Department of Primary Industries, Wagga Wagga NSW, Australia.


Canola is one of the major crops planted across Australia’s wheatbelt. Water shortages and uneven distribution of water resources are the key limitations for Australia canola productivity. This is expected to be aggravated in the warmer and dryer future climates with higher rainfall variability, leading to a threat to Australia canola industry. However, the increase of atmospheric CO2 concentration has the potential to increase crop yield and water use efficiency (WUE). Therefore, there is a need to conduct a comprehensive assessment by combining the impacts of the changes in future climate and atmospheric CO2 concentrations on canola yield and WUE for providing a fundamental insight for future Australia canola industry. In this study, we tested APSIM-Canola module against the experimental data, collected in 2013-2014 and 2016 in Wagga Wagga. The tested model was then used to predict canola yield and WUE in both historical and future climatic conditions. The simulation results showed ASPIM-Canola module captured the variations of canola yield across fertilizer applications and climatic variations. Comparisons between historical and projected future climates, there is an overall tendency for a decline of cumulative rainfall in canola growing seasons and an increase of air temperature. As a consequence, the increasing temperature and decreasing rainfall leads to a clear decline of canola yield and WUE, however, this negative impact could be offset by the positive impact of increasing atmospheric CO2 concentration on canola yield and WUE. This scenario analysis provides a foundation towards understanding changes in Australia’s canola cropping systems.

Impact of crop species and crop sequencing on nematode, crown rot and common root rot inoculum loads

Andrew Verrell1, Jeremy Whish2, David Lawrence3, Lindsay Bell2, Darren Aisthorpe3, Jon Baird1, Jayne Gentry3, Greg Brooke1, Andrew Erbacher3, Andrew Zull3, Kaara Klepper4

1NSW Department of Primary Industries, Tamworth, NSW, 2340,

2 CSIRO Agriculture, St Lucia QLD 4067

3Qld Department of Agriculture and Fisheries, Toowoomba, Qld, 4350

4 GRDC Toowoomba Qld 4350



Farming systems are underperforming in terms of water limited yield potential, due to challenges that include declining soil fertility, herbicide resistant weeds and increasing soil pathogens. Seven long term farming systems sites were established in 2015 across different environments from Trangie to Emerald to investigate how modifications (cropping intensity, legume frequency, cropping diversity and nutrient management strategies) to cropping systems will impact on their performance. Four major pathogens; root lesion nematodes, (Pratylenchus thornei and Pratylenchus neglectus), crown rot (Fusarium pseudograminearum) and common root rot (Bipolaris sorokiniana), were monitored, using the PREDICTA® B DNA-based soil test, across the sites and crop sequences. The effect of individual winter and summer crop species and their combined effect in a range of crop sequences, on the changes in DNA pathogen loadings, are reported.

Intercropping increases productivity in the South Australian Mallee

Penny Roberts1, Michael Moodie2, Nigel Wilhelm3

1 SARDI, 155 Main North Road, Clare, SA, 5453,

2 Frontier Farming Systems, 7B Byrne Court, Mildura, Victoria, 3500

3 SARDI, GPO Box 1671, Adelaide, SA, 5001


Intercropping has the potential to provide production and sustainability benefits in low rainfall dryland cropping systems. With a small number of growers adopting break crop intercropping in the SA Mallee environment there is demonstrated potential for this practice to be adopted more widely.

Two years of field based research was undertaken at Waikerie in the South Australian Mallee to investigate break crop species mixes suited to this environment. The trials conducted in 2016 and 2017 focused on pulse/canola intercrops and were compared to monoculture stands of the intercrop components. Grain yield, biomass and soil nitrogen were measured to determine the relative benefit of the different intercrops.

There was over-yielding in all intercrop combinations, demonstrating that increases in productivity of 12 to 80% are achievable in this Mallee environment. An economic analysis demonstrated that most intercrops combinations had similar or higher gross margins than the monoculture crops in both years, with the benefits greater in seasons with more favourable growing season conditions.

This work demonstrates that intercropping has the potential to increase both productivity and financial returns in low rainfall cropping regions. In addition, the adoption of this practice could lead to ancillary benefits such as increasing groundcover on erosion prone soils.



The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

Photo Credits

David Marland Photography Graham Centre for Agricultural Innovation, Charles Sturt University

Conference Managers

Please contact the team at Conference Design with any questions regarding the conference.

© 2015 - 2019 Conference Design Pty Ltd