Comparing strategic deep tillage options on soil constraint removal and crop performance across two soil types in Western Australia

Stephen Davies1, Tim Boyes2, Liz Petersen3, Chad Reynolds1, Joanne Walker1, Ty Fulwood4, Rob Dempster5

1 Department of Primary Industries and Regional Development, 20 Gregory Street, Geraldton, Western Australia, 6530,,,
2 agVivo, PO Box 80, Stoneville, Western Australia, 6081,
3 Department of Primary Industries and Regional Development, 3 Baron-Hay Court, South Perth, Western Australia 6151,
4 ‘Meenar’ Farm, Meckering, Western Australia, 6405,
5 ‘Adair’ Farm, Goomalling, Western Australia, 6460


Over the past 10-years numerous strategic deep tillage methods have been developed for ameliorating sandplain soil constraints in WA. Degree of soil disturbance varies: deep ripping loosens soils with low topsoil impact; ripping with inclusion generates seams of incorporated topsoil; deep mixing incorporates topsoil and amendments to 0.3-0.4m; and inversion buries topsoil (and weed seeds) in layers at 0.15-0.4m. Replicated field experiments comparing 13 strategic deep tillage combinations, were established on deep sand (0.4-0.6 m) over clayey gravel (duplex sandy gravel) and deep yellow sand in 2016 and 2017, respectively. On duplex sandy gravel, treatments with deep ripping to 0.5m+ increased wheat yields by 39-49% in 2017, but combining ripping with mixing or inversion has had more sustained yield increases of 42-62% in barley for 2018. For the deep sand, which has limited capacity to store water, grain fill was compromised on mixed or inverted soils, with deeper ripping better matched to crop water supply in both 2017 and 2018. At this site a loss of tillers between 22 August and 12 November in 2018 reflected dry, hot conditions through September with greater losses for some of the deep mixed and inverted treatments which had higher yield potential that could not be met.

Improving the adoptability of spading practices in constrained sandy soil environments

Jack Desbiolles1, Chris Saunders1, Chris McDonough2, Michael Moodie3

1 Agricultural Machinery Research and Design Centre, School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia,,
2 Insight Extension for Agriculture, Loxton, SA, 5333.
3 Frontier Farming Systems, Mildura, Victoria 3500


With increasing adoption of sandy soil amelioration practices such as spading, minimising the risks of soil erosion post-operation is of paramount importance. Solutions being researched include developing effective and practical ways to i) keep surface residue in spaded paddocks and/or ii) reliably establish a vigorous (cover) crop as quickly as possible after spading. One-pass ‘spade and sow’ approaches have been developed and evaluated to effectively address the challenges of early crop establishment and problems associated with subsequent sowing in soft spaded soil. ‘Strip spading’ concepts are also being evaluated whereby strips within a paddock are spaded in turn over a cycle of two to three years to gradually ameliorate the constrained area, leaving residue protection in unspaded zones each season. At the paddock scale, 4.5 m wide spading of harvester trail strips incorporates concentrated crop residue as organic input, as well as weed seeds, achieving clear benefits in soil water use and grain yield. At the machine scale, modifications can be made to spade and sow 350mm wide strips every 700mm, leaving bands of surface or standing stubble between emerging crop rows. This evaluation work conducted across a variety of projects is on-going.


Reduced frost damage on crops after strategic deep tillage – evidence from field experiments in Western Australia

Giacomo Betti1, Tom Edwards1, Ben Biddulph1, Stephen Davies1, Andrew Van Burgel1, David Hall1 and Chloe Turner2

1 Department of Primary Industries and Regional Development (DPIRD), 3 Baron-Hay Ct, Kensington, WA, 6000.,
2 Facey Group, 40 Wogolin Rd, Wickepin, WA, 6370


Soil amelioration for the management of water repellent soils (Betti et al. 2018) can potentially reduce crop damage in frost prone areas as suggested by several anecdotal and research reports (Rebbeck et al. 2007). Subsoil clay addition (by clay delving) has been demonstrated to reduce frost damage in wheat (Rebbeck et al. 2007). Some evidence indicates a possible benefit from soil amelioration with deep tillage (Butcher et al. 2017) but was insufficient to prove a direct link between soil amelioration and a reduction in frost severity and duration. By comparing multiple sites in different seasons, this research demonstrates that amelioration with strategic deep tillage (i.e. rotary spading) can reduce frost severity and duration and presents evidence that this reduced crop damage, can contribute to improved productivity.

Long term impacts on crop productivity following amelioration of a sandy soil

Melissa Fraser1, Nigel Wilhelm2 and David Davenport3

1 Primary Industries and Regions South Australia (PIRSA), 74 Struan House Rd, Naracoorte, SA, 5271,,
2 South Australian Research and Development Institute, PIRSA, Urrbrae, SA, 5064,
3 PIRSA, Port Lincoln, SA, 5606


Crop water-use on sandy soils is often poor with productivity constrained by the presence of water repellence, compaction, low water holding capacity and/or poor nutrient and biological fertility. Treatments that addressed these constraints were applied in a field trial on the Eyre Peninsula in 2014. Crop responses and changes in soil fertility have been measured. Physically mixing the soil to 0.3 m by spading was beneficial on this sand; yield responses in the order of 70 to 100 % were seen in 2018, five years after treatments were applied (unmodified control = 2.35 t/ha); further yield increases in the first two years were obtained with the incorporation of lucerne hay in the spading operation.

Similar results were seen in comparable trials in the Murray Mallee and South East of SA, confirming that crop performance on sandy soils can be substantially improved when their inherent constraints are addressed. Understanding the nature and interaction of the constraints is vital to identify the optimum amelioration strategy.

Sensitivity of lentil genotypes to photosynthesis-inhibiting (Group C) herbicides

Tim Nigussie1, Jason Brand1, Mitchell Fromm1, Laura James1, Larn McMurray2

1 Agriculture Victoria, Department of Jobs, Precincts and Regions, 110 Natimuk Road, Horsham, Vic, 3400,, 
2 Global Grain Genetics, Clare, SA, 5453


Lentil (Lens Culinaris M.) is a poor competitor with weeds and its sensitivity to herbicides make broad-leaf weed control challenging. Herbicide resistance due to overreliance on group B herbicides in herbicide resistant crop varieties has also become a concern. Group C herbicides control many broad leaf and some grass weeds. However, this group of herbicides have a low safety margin between phytotoxicity to weeds and to the lentil crop. Field experiments evaluated the Group C herbicide sensitivity of three lentil genotypes PBA Hurricane XT, PBA Jumbo and PBA Jumbo 2 in comparison to a new genotype (SP1333) with improved metribuzin tolerance. Diuron, simazine, metribuzin and terbuthylazine were applied post-sowing pre-emergence at various rates. All genotypes did not show sensitivity to 765 gai/ha of diuron and up to 3600 gai/ha of simazine and produced grain yield equivalent to their respective nil treatment. However, application of higher rates of metribuzin and terbuthylazine caused significant injury and a subsequent yield loss of up to 100%. SP1333 had better tolerance to lower rates of metribuzin, terbuthylazine and higher rates of diuron than PBA Hurricane XT, PBA Jumbo and PBA Jumbo 2, providing opportunity for breeding programs to develop varieties with improved tolerance to group C herbicides.

Agronomic options to overcome soil water repellence improve crop performance regardless of sowing conditions in a gravelly duplex soil

G.P. McDonald1, S.L. Davies2, D.M. Bakker1, G. Poulish1

1 Department of Primary Industries and Regional Development, 444 Albany Highway, Albany, WA, 6330,,, 
2 Department of Primary Industries and Regional Development, 20 Gregory St, Geraldton, WA, 6530


Soil water repellence (SWR) is a significant constraint to crop establishment in South-West Western Australia (WA). A long term agronomic experiment commenced in 2015 to investigate a range of potential amelioration and mitigation options to manage SWR. All treatments improved crop establishment and yield by varying amounts over four seasons. The most effective treatments for improving yield were strategic deep tillage and banded wetting agents. Strategic deep tillage via mouldboard plough (MBP) or one-way plough (OWP) improved yield in all seasons regardless of rainfall patterns. The application of pre-emergent herbicides on strategic deep tillage treatments trended towards reduced crop growth and yield but rarely to a significant level. Near-row sowing increased plant establishment in two of the four seasons but yield improvements in these seasons were significantly lower than almost all other treatments. Improved crop performance from wetting agent techniques occurred only in years with dry soil conditions at sowing. Wetting agents were proven to be a good short term option for water repellent soils but strategic deep tillage provided the most consistent longer term yield improvement across all the growing seasons experienced.

A field method to assist selection of wheat varieties best suited to local soils may be the best strategy for mitigating waterlogging risk.

Sam North1, Carlos Ballester Lurbe2, James Brinkhoff2 and Alex Schulz1

1 NSW DPI, 449 Charlotte St, Deniliquin, NSW, 2710, website, Email, 
2 Centre for Regional and Rural Futures (CeRRF), Deakin University, Research Station Rd, Hanwood, NSW, 2680


Waterlogging is a major constraint to wheat yields in Australia. There is genetic diversity for waterlogging tolerance in wheat and there is a need to improve wheat yields on waterlogging prone soils through identification of more tolerant varieties. This study aimed to (i) assess the usefulness of redox potential (Eh) and canopy temperature (Tc) to explain wheat responses to waterlogging and; (ii) determine whether there is sufficient variability in current, commercially available wheat varieties to justify trials on local, waterlogging prone soils. Ten varieties were examined, with control and waterlogged treatments imposed at two sites. Waterlogging was imposed at anthesis, with water ponded on plots for 14 days. Measurement of Eh allowed differences in the responses of varieties to waterlogging at the two sites to be understood. Canopy temperature was also useful at showing differences between the varieties. There were clear differences in the responses of currently recommended wheat varieties to both soil type and to waterlogging. Local trials on waterlogging prone soils are needed to allow wheat growers to select the best varieties for their soils.


Low-risk management strategies for crop production on water repellent sands

Phil Ward1, Nigel Wilhelm2, Margaret Roper1, Terry Blacker3, Ramona Kerr1, Priya Krishnamurthy1, Ian Richter4, Shayne Micin1

1 CSIRO, Private Bag No 5, Wembley WA 6913;,
2 SARDI-PIRSA, Waite Research Precinct, Hartley Grove, Urrbrae SA 5064,
3 SARDI, 119 Verran Tce, Port Lincoln SA, 5606,
4 PIRSA, 226 McKenzie Rd, Minnipa SA 5654,


Water repellent (non-wetting) soils pose significant problems for crop production and natural resource management in southern Australia. Water infiltration is patchy, and the resulting impacts on crop and weed germination can reduce yields by more than 50%. In this research, we compared the impacts of two wetting agents and near-row sowing as low-cost strategies to improve crop emergence and yield. A randomised block trial with 4 replicates was established on a sandy soil near Wharminda on the Eyre Peninsula in SA. Wetting agents improved crop emergence in wheat (2015: 47-58%), barley (2016: 44-111%) and lupins (2017: 210-326%), and increased grain yield in 2015 (26-31%) and 2017 (26-70%) but had no impact in 2016. Near-row sowing had no significant impact on either emergence or crop yields. Neither wetting agents nor near-row sowing had any direct impact on severity of soil water repellence.

Promoting soil health in dryland agriculture by increasing cropping intensity

Alwyn Williams1, Lindsay W. Bell2

1 School of Agriculture and Food Sciences, The University of Queensland, Gatton, QLD 4343,,
2 CSIRO, 203 Tor Street, Toowoomba, QLD 4350


Extended fallow periods are implemented in dryland cropping systems to allow recharge of soil moisture for the subsequent crop. Over time, fallow periods deplete soil carbon (C), a foundation of soil health that affects soil microbial activity and the long-term capacity of soils to store moisture. Reducing fallow periods by increasing cropping intensity (e.g. cover or double cropping) can promote soil health and thereby contribute to the long-term sustainability of dryland cropping systems. However, the agronomic feasibility of increasing cropping intensity in dryland systems is unknown. Using a cropping systems experiment in southeast Queensland, we investigated the impacts of cover and double cropping on indicators of soil health and sorghum grain yields in comparison to conventional fallow-based cereal production systems. Both cover and double cropping systems increased concentrations of soil C compared with the conventional systems. In the cover crop system, this was associated with greater soil microbial activity and improved surface soil moisture storage at crop establishment. Additionally, sorghum grain yield in the cover crop system did not differ significantly from those in the conventional systems. In contrast, the double crop system depleted soil moisture reserves leading to dramatic yield loss as well as reduced nitrogen- and water-use efficiency. Our results demonstrate that reducing fallow periods via cover cropping is a potentially feasible method for promoting soil health in subtropical dryland cropping systems. Longer-term research is required to determine the trade-offs and tipping points associated with the use of cover crops in drylands.

Addressing subsoil acidity in the field with deep liming and organic amendments: Research update for a long-term experiment

Guangdi Li1,3, Richard Hayes1,3, Jason Condon1,2,3, Sergio Moroni2,3, Ehsan Tavakkoli1,3, Helen Burns1, Richard Lowrie1, Adam Lowrie1, Graeme Poile1, Albert Oates1, Andrew Price1 and Alek Zander2

1 NSW Department of Primary Industries, Pine Gully Road, Wagga Wagga, NSW 2650,,,
2 Charles Sturt University, Boorooma Street, Wagga Wagga, NSW 2650,
3 Graham Centre for Agricultural Innovation, Albert Pugsley Place, Wagga Wagga, NSW 2650


A long-term field experiment was established in 2016 to manage subsurface soil acidity through innovative amelioration methods with the aim to increase productivity, profitability and sustainability. Deep placement of lime increased soil pH and reduced exchangeable Al% at the depth where lime was placed, but there was no evidence to show vertical alkalinity movement during the first 3 years of the experiment.  Deep placement of lucerne pellets did not increase soil pH as much as expected, but reduced exchangeable Al%. Significant yield improvement was recorded from deep placement of lucerne pellets in a wet year (2016) but not in dry years experienced in 2017 and 2018, although large amount of mineral nitrogen was measured in autumn in 2017. Crop performance and soil chemical, physical and biological properties will be continually monitored to understand plant-soil interactions, the factors driving the differences in crop response to various treatments, and the long-term residual value of soil amendments.



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.

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

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