A Journey in the Application of Research into Subsoil Manuring in the High Rainfall Zone of Victoria

Robert Binks1, David Watson2

 1Yaloak Estate, 4662 Geelong-Ballan Rd, Ballan, Victoria, rob@yaloakestate.com.au, 
2 Yaloak Estate, 1504 Geelong Rd, Mt Clear, Victoria, davdrwatson0@gmail.com 


Yaloak Estate at Ballan in Victoria’s HRZ began the journey of investigation into how to realize the productive potential of the property 25 years ago. Cropping on raised beds in the 1990’s led to dramatic yield improvements but we still weren’t capturing the full water use potential that our climate could deliver. Wheat crops reliably yielding 8-10t/ha was our goal. Research commenced around 2000 and has been focussed and ongoing ever since. Hostile sodic sub soils were rapidly identified as the major impediment, so the means of ameliorating these became our goal. Subsoil manuring (SSM) using high rates of organic amendments injected into the interface of top soil and subsoil has delivered many of the gains we had hoped for and Yaloak now has the machinery and expertise to do this on a large scale. However, the research journey of understanding the specific subsoil issues within paddock, property and region and how they may be fixed, continues.

Constraints to nodulation and N2 fixation of pulses on acid soils of the south-east Australian high rainfall zone

Mark R. Norton1,2, Helen Burns1, Peter Tyndall1, Laura Goward3 and Mark B. Peoples3

1 Agricultural Institute, Wagga Wagga, NSW, 2650, Australia, www.dpi.nsw.gov.au, mark.norton@dpi.nsw.gov.au,
2 Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, NSW 2650, Australia.
3 CSIRO Agriculture and Food, Canberra ACT 2601, Australia


This project aimed to identify factors limiting nodulation, N2 fixation and productivity of pulse crops grown on acidic soils in the high rainfall zone (HRZ) southern grain production region. To assess the extent and nature of limiting factors 45 commercial pulse crops, across a region extending from Woodstock in NSW to Frances in the Lower South-East of SA, were surveyed.  The survey assessed the level of nodulation and N2 fixation achieved from a range of stunted and vigorous pulse crops. Differences in crop biomass and N2 fixation were associated with seasonal variability while soil subsurface acidity was a major and widespread constraint to nodulation. Sixteen site/season combinations from SW Victoria and the Lower South-East SA are examined in greater detail to illustrate the complexity associated with pulse productivity and N2 fixation.


The effect of soil moisture at application on the behaviour of four nitrogen fertilisers in the presence of 3,4-dimethylpyrazole phosphate

Brooke Kaveney1, Jason Condon1, Greg Doran1

1 Graham Centre for Agricultural Innovation, Wagga Wagga, NSW, 2650, www.grahamcentre.net, bkaveney@csu.edu.au


A laboratory soil incubation experiment was conducted using the nitrification inhibitor 3,4-dimethylpyrazole phosphate in conjunction with four different agriculturally relevant nitrogenous fertilisers to examine the effects of soil moisture at application on inhibitor behaviour. Soil moisture influenced the mineral N concentrations of the nitrogen fertilisers.  Fertilisers that were applied to moistened soils recorded significantly higher mineral N concentrations than when they were applied to dry soils. Of the four fertilisers applied to a moistened soil, urea had the lowest NH4+ and NO3 concentrations after a week of incubation. However, in dry soils both urea and UAN recorded significantly lower mineral N concentrations. Losses were attributed to volatilisation which occurs as urea is converted to NH4+. Regardless of the soil moisture conditions, DMPP effectively suppressed nitrification for all fertilisers. Fertilisers without DMPP recorded higher NO3 concentrations as the NH4+ was oxidised as part of the nitrification process. Experimental results demonstrate that different soil moisture conditions can influence the behaviour of nitrogen fertilisers but not DMPP.

A novel approach to map the depth to a soil pH constraint – a useful tool for understanding yield variability

Patrick Filippi*1, Edward J. Jones1, Bradley J. Ginns1, Brett M. Whelan1, Guy W. Roth1, Thomas F.A. Bishop1

1 The University of Sydney, Sydney Institute of Agriculture, Sydney, New South Wales, Australia, patrick.filippi@sydney.edu.au 


Subsoil alkalinity is a common issue in the alluvial cotton-growing valleys of northern NSW, Australia. This causes nutrient deficiencies, toxicity, and inhibits root growth, which can have a damaging impact on crops. The depth at which a soil constraint is reached is important information for farmers, however, this is hard to measure spatially. This study predicted the depth in which a pH constraint (pH > 9) was reached to a 1 cm vertical resolution for a 1 m soil profile on a dryland cropping farm in northern NSW, Australia. Equal-area quadratic smoothing splines were used to resample vertical soil profile data, and a random forest model was used to produce the depth-to-pH-constraint map. The model to spatially predict soil pH across the farm was accurate, with an LCCC of 0.63, and an RMSE of 0.47 when testing with leave-one-site-out-cross-validation. About 77% of the area was constrained by a pH greater than 9 within the top 1 m of soil. The relationship between the predicted depth-to-pH-constraint map and cotton and grain (wheat, canola, and chickpea) yield monitor data was analysed for individual fields. The deeper in the soil profile a pH constraint was reached, the greater the crop yield. A strong relationship was found for wheat, canola, and chickpea (Spearman’s correlation (rs) of 0.75, 0.66, and 0.58, respectively), and a moderate relationship for cotton (rs = 0.37). The modelling approach presented could be used to identify the depth to other soil constraints, such as soil sodicity. The outputs are a promising opportunity to understand crop yield variability, which could lead to improvements in management practices.

Ripping Mallee soils, what are the production benefits?

Kate Finger1, Audrey Delahunty¹, Claire Browne2, James Nuttall³, Ashley Wallace³, Darryl Pearl⁴, Peter Fisher⁵, Colin Aumann⁵, Jeff Tullberg⁶, Nigel Wilhelm⁷

¹ Agriculture Victoria, Corner Eleventh St & Koorlong Ave, Irymple, Victoria, 3498,
² Birchip Cropping Group, 73 Cumming Avenue, Birchip, Victoria, 3483,
³ Agriculture Victoria, 110 Natimuk Road, Horsham, Victoria, 3400,
⁴ Agriculture Victoria, 324 Campbell Street, Swan Hill, Victoria, 3585,
⁵ Agriculture Victoria, 255 Ferguson Road, Tatura, Victoria, 3616,
⁶ Australian Controlled Traffic Farming Association, 823 Hitchcock Road, Buninyong, Victoria, 3357,
⁷ SARDI, Waite Campus, 2b Hartley Grove, Urrbrae, South Australia, 5064 


Historical soil compaction due to random and extensive machinery traffic within paddocks is known to limit crop production.  Physically ameliorating the soil via deep ripping is used to alleviate such compaction and when combined with controlled traffic farming (CTF) benefits may be prolonged.  Previous deep ripping work has demonstrated improved water infiltration and root access to nutrients and water deeper in the profile across various soils.  Research trials were established in 2018 at Woomelang and Kooloonong to determine the effect of deep ripping, with and without inclusion plates on Mallee soils.  Yield improvements of 0.5 t/ha were recorded at Kooloonong, on a deep sand after ripping without inclusion plates to a depth of around 40 cm.  However, no significant yield response was recorded at Woomelang on either a sand over sandy loam dune or sandy loam over clay loam swale where ripping was applied to an average depth of 20 cm.  This indicates that the immediate value of deep ripping is highly dependent on soil type, ripping depth and stored soil water. Multi-year studies are required to assess the long-term value of deep ripping.

Seeder-based approaches to mitigate the effects of sandy-soil constraints

Desbiolles J1, McBeath T2, Barr J1, Fraser M3, Macdonald L2, Wilhelm N4, Llewellyn R2

1 University of South Australia, Mawson Lakes, SA, 5095, jack.desbiolles@unisa.edu.au, 
2 CSIRO Agriculture and Food, Urrbrae, SA, 5064,
3 Primary Industries Resources South Australia, Struan, SA, 5271,
4 South Australian Research and Development Institute, Urrbrae South Australia, Australia


Solutions to mitigate the impacts of soil constraints, such as annual interventions at seeding, offer lower cost alternatives to full profile amelioration options. The concept of a fertility strip over a permanent seed row zone has been investigated since 2017 at a low fertility sandy site, using a range of mineral (clay, fertiliser) and organic (composted manure, biochar) inputs into the furrow at sowing. 0.5 t/ha grain yield responses to edge-row sowing with a further 0.4-0.6 t/ha in yield responses to 200 mm deep-furrow till have been achieved. An evaluation of 13 different soil wetter treatments at a severely water-repellent site showed the potential to more than double wheat establishment and generate up to 21% (or 0.22 t/ha) grain yield response, as a result. The data also suggest specific soil wetter chemistries may promote later season effects associated with specific yield gains. Discrete Element Method computer simulations of soil/tool interactions are also being investigated to guide the modifications of furrow openers and seed banding attachments to better control furrow backfill in water-repellent soil environments and secure seed placement into underlying moisture.

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, www.dpird.wa.gov.au, stephen.davies@dpird.wa.gov.au,
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.

The use of computer simulation as a decision making tool to improve machinery set-up, usage and performance.

Mustafa Ucgul1, Chris Saunders1, Jack Desbiolles1

1 Agricultural Machinery Research and Design Centre, School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia   –  E: mustafa.ucgul@unisa.edu.au,


Discrete element method (DEM) is a powerful computer simulation technique that can model soil and machinery interactions and predict aspects of soil manipulation and amendment incorporation within the soil profile. DEM can investigate different operation parameters without the need for expensive and time consuming field tests that can only be undertaken at certain times of the year. In this paper two different tools used for soil amelioration; namely the rotary spader and deep rippers with inclusion plate attached, have been investigated using DEM. The simulation results were also validated by performing a series of field tests. Result of the study showed that rotary spaders, commonly chosen to bury and mix soil amendments, resulted in large differences in the uniformity of mixing depending upon the machine set-up and operation. It was also found from the results of ripping with inclusion plate simulations that the amount of surface amendment material incorporated to deeper soil layers decreases with increasing forward speed and ripping depth. Results also showed that (further improvement is required in inclusion plate design for improved top-down material incorporation and the effect of surface amendment burial on crop response also needs further research

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, chris.saunders@unisa.edu.au,
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.


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 david_marland@hotmail.com Graham Centre for Agricultural Innovation, Charles Sturt University

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