Incorporating lime on forest gravel soils to combat soil acidity

CC BY 4.0

Research organisatons
Funding source

Trial details


To improve the adoption of liming practices in the medium to high rainfall zone of Western Australia by demonstrating the economic and environmental benefits of lime application and incorporation.

Key messages


Can incorporation of lime economically remediate a subsoil acidity constraint on gravel soils?


  • To evaluate four rates of lime
  • To compare three methods of incorporating lime
  • To investigate an optimal combination of application rate and method of incorporation for ameliorating soil acidity



Forest gravel soils are common in the medium to high rainfall zone of Southern Western Australia and are estimated to account for about 2.4 million hectares of the state's farming area.  Non-wetting and soil acidity issues are known to constrain the productivity of these soil types, which are common throughout the Southern DIRT region. Considering this, limited local research has been conducted in regards to the effects of incorporating lime as a method to alleviate these soil constraints more effectively and economically than the traditional method of top-dressing.

The trial was collaboratively designed by Southern DIRT R&D committee members and staff, Wes Lefroy of Precision SoilTech, and the landholders, Roger and Simon House.  The focus of the treatments was to;

a)  Utilise the most economic source of lime for the landowners,

b)  apply the lime at a range of rates representative of both local practice and industry endorsed practice, and

c)  incorporate the lime with equipment which are known to improve the movement of lime through the soil profile compared to top-dressing; while having minimal complicating factors (i.e. poor seed placement) which are commonly associated with other forms of deep tillage.

The trial is located 12 km north of Kojonup and was chosen for its combination of targeted soil type (forest gravel) and pH range (4.5 – 4.8 CaCl2) up to a depth of 60cm.



The methods for incorporating lime in the trial are offset discs and one way plough, with knife-points at seeding included as a control.  Both offset discs and one way ploughs are generally used for the shallow incorporation of lime, and in this trial the depth achieved was approximately 10cm for the offset discs and 12cm for the one way plough. Research has shown that these incorporation methods can be more effective than the standard practice of top-dressing lime at increasing soil pH at depth by mixing lime into the soil profile when adequate rates are applied. While the lime is mixed well to the working depth of the implements, neither of these methods have the capacity to incorporate lime to depths beyond 20 cm.

Both offset discs and one way ploughs are considered by local growers as more cost-effective options for incorporating lime when compared to other methods (i.e. rotary spading). Annual plot soil testing and harvest yield will be the primary indicators used to assess how quickly and effectively the various treatments are able to raise pH at depth and increase production on forest gravel soils constrained by subsoil acidity.

Lead research organisation Southern DIRT
Host research organisation N/A
Trial funding source GRDC LIE00008
Related program N/A

Southern DIRT would like to thank Roger and Simon House of “Starhaven” for hosting, implementing and maintaining the trial; also for supplying the lime and investing significant time modifying the one way plough used in the trial, Wes Lefroy from Precision SoilTech for his assistance locating the site and designing the trial, Vivek Bhat for overseeing implementation of the trial as the Southern DIRT Project Officer at the time, and Southern DIRT members for their valuable input into determining the aims of the trial.

This trial is supported by GRDC funding through LIE00008: Working together to deliver multiple benefit messages to growers through a whole systems approach to soil management.

Soil acidity management strategies throughout Western Australia are available for download from:

Other trial partners Not specified
Download the trial report to view additional trial information


Crop type Wheat
Treatment type(s)
  • Soil
Trial type Experimental
Trial design Randomised,Replicated

Kojonup 2015

Sow rate or Target density 100 kg/ha
Sow date 29 May 2015
Harvest date Not specified
Plot size 11m x 30m
Plot replication 4
Paddock history 2012 barley, 2013 fallow, 2014 quinoa

29/05/2015:  100kg Allstar

04/07/2015:  50kg Urea

01/08/2015:  60kg Urea


22/05/2015:  1.5L Glyphosate, 16mL Nail

29/05/2015:  100kg Allstar & 4L/t Impact

21/07/2015:  750mL Tigrex



22/05/2015: 100mL Dominex

21/07/2015: 100mL Dominex


18/09/2015:  145 mL/ha Folicur 430 SC

Download the trial report to view additional method/treatment information

Download results

Trial results Table 1

# Variety
Assessment (assessment) Crop Stage (stage)
1 27/06/2015 Establishment assess 4 leaf - 1st tiller
2 5/08/2015 Establishment assess Mid - late tillering
3 20/08/2015 Normalized Differenc Late tillering - 2nd
4 21/10/2015 Shoot biomass Mid - late flowering
5 10/12/2015 Harvest yield and gr Maturity

Assessment assessment


Crop Stage stage

Observed trial site soil information
Trial site soil testing
Site Depth Type pH EC P K N A OC CAT
Kojonup, WA 0 - 10cm Forest Gravel 4.70
Kojonup, WA 10 - 20cm Forest Gravel 4.70
Kojonup, WA 20 - 30cm Forest Gravel 4.90
Kojonup, WA 30 - 60cm Forest Gravel 5.00
Soil conditions
Trial site Soil texture
Kojonup, WA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Kojonup, WA Chromosol
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 Kojonup WA
2015 323.0mm
2014 318.3mm
2013 324.6mm
2012 338.4mm
2011 364.2mm
2010 292.8mm
2009 347.8mm
2008 332.2mm
2007 326.9mm
2006 307.8mm
2005 342.2mm
2004 315.6mm
2003 302.3mm
2002 263.8mm
2001 268.6mm
2000 367.5mm
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



Kojonup WA 2015

Observed climate information

Rainfall trial total (mm) 440.4mm
Rainfall trial gsr (mm) 355.6mm

Derived climate information

Kojonup WA


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: 04-09-2017 15:01pm AEST