Trafficking a heavy Minnipa soil does not hurt crop production but beware on deep sands


Research organisatons
Funding source

Trial details

Researcher(s) Nigel Wilhelm (SARDI), Peter Fisher (AgVic), Chris Bluett (ACTFA) and Rebecca Mitchell (AgVic)
Year(s) 2018
Contributor SARDI Minnipa Agricultural Centre
Trial location(s) Site 18, Minnipa Agricultural Centre, SA
Related trials
Trafficking a heavy Minnipa soil does not hurt crop production but beware on deep sands locations

This article summarises the first four years of crop performance after trafficking was imposed on a red calcareous sandy loam at Minnipa Agricultural Centre (a detailed summary of 2015, 2016 and 2017 results can be found in the 2015, 2016 and 2017 Eyre Peninsula Farming Systems Summaries, respectively). Three other trials similar in design and monitoring have also been implemented across the LRZ – on a deep sand at Loxton (SA), a brown loam near Swan Hill (Vic) and on a deep red earth at Lake Cargelligo (NSW). All these trials except Swan Hill (land ownership has changed) have been maintained for at least the five years of the project. A new trial was set up in 2018 to investigate the role of CTF on a deep sand which has been ameliorated with deep ripping.

Key messages
  • Over the last four years, trafficking at any level has not decreased crop production on a heavy Minnipa soil so moving to controlled traffic farming on this soil type is not likely to increase crop production due to less trafficking in the paddock.
  • Trafficking on a deep sand (trial at Loxton in the northern mallee) has substantially reduced crop production for at least 4 years so CTF may have additional benefits on deep sands, especially if ripping is used to correct existing compaction.
  • Similar to many previous trials, ripping has not benefited production on the heavy Minnipa soil.
Lead research organisation Australian Controlled Traffic Farming Association Inc.
Host research organisation SARDI Minnipa Agricultural Centre
Trial funding source GRDC ACT00004
Related program Application of CTF in the low rainfall zone

Thanks to MAC farm staff for the implementation and management of the R site and to Ian Richter, Brett Hay and Naomi Scholz for undertaking the monitoring of crop performance and soil condition. GRDC is the major funder of this project, which is managed by the Australian Controlled Traffic Farming Assocation.

Other trial partners Agriculture Victoria
Download the trial report to view additional trial information


Crop type Wheat
Treatment type(s)
  • Soil: Compaction
  • Soil amelioration: Type
Trial type Experimental
Trial design Randomised,Replicated

Minnipa Agricultural Centre 2018

Sow rate or Target density 75 kg/ha
Sowing machinery

The original R trials were designed and implemented to be the same at all four sites. Each trial consists of 5 treatments replicated 4 times:

  1. Control (no heavy vehicle trafficking).
  2. One pass of a 20 tonne vehicle prior to seeding when soil was dry.
  3. One pass of a 20 tonne vehicle prior to seeding when soil was wet.
  4. Three passes of a 20 tonne vehicle prior to seeding when soil was wet.
  5. Deep ripping (to loosen any historical trafficking).

These passes were implemented in 2015 with 50% overlap of the load bearing wheels to ensure even coverage and were not be re-imposed.


The trafficking treatments simulate the effect of compaction caused by trafficking of heavy vehicles, with three passes when the soil is moist as an extreme (soil is always softer when wet so compac

Sow date 25 May 2018
Harvest date Not specified
Plot size 50m x 3m
Plot replication 4

70 kg/ha of Granulock Z (11:22 1% Zn).

Download the trial report to view additional method/treatment information

Download results

Trial results Table 1

# Treatment 1
Grain yield (t/ha) Sowing depth (mm) (mm) Anthesis biomass (t/ha) Shoot dry weight (t/ha) Establishment plants (plants/m2)
1 Control 2.32 35 3.64 0.18 135
2 Single trafficking on dry soil 2.38 31 3.96 0.22 130
3 Single trafficking on wet soil 2.13 36 3.34 0.15 111
4 Multi trafficking on wet soil 2.19 39 3.09 0.14 118
5 Ripping 2.14 31 3.39 0.21 140

Grain yield t/ha


Anthesis biomass t/ha


Establishment plants plants/m2


Shoot dry weight t/ha

Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Site 18, Minnipa Agricultural Centre, SA Calcareous red sandy loam
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Site 18, Minnipa Agricultural Centre, SA Calcarosol
Soil Moisture Source: BOM/ANU
Average amount of water stored in the soil profile during the year, estimated by the OzWALD model-data fusion system.
Year Site 18, Minnipa Agricultural Centre SA
2018 417.9mm
2017 437.2mm
2016 409.0mm
2015 381.0mm
2014 439.7mm
2013 385.5mm
2012 407.7mm
2011 453.8mm
2010 454.3mm
2009 466.5mm
2008 380.6mm
2007 367.6mm
2006 384.7mm
2005 350.4mm
2004 343.8mm
2003 348.6mm
2002 343.5mm
2001 396.8mm
2000 422.6mm
National soil grid Source: CSIRO/TERN
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties



Site 18, Minnipa Agricultural Centre SA 2018

Observed climate information

Rainfall avg ann (mm) 325mm
Rainfall avg gsr (mm) 242mm
Rainfall trial total (mm) 244mm
Rainfall trial gsr (mm) 186mm

Derived climate information

Site 18, Minnipa Agricultural Centre SA


Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.

Trial last modified: 08-10-2019 14:59pm AEST