2015 Soil Acidity and pH Management for Central West Farming Districts

2015 sampling for the CWFS, GRDC funded, soil acidity project is now complete.

To provide a brief overview of the outcomes:

As shown in Table 1, five out of seven sites sampled in the year 2000, as part of a previous soil acidity project, demonstrate an increase in acidification.

Out of 17 “new” sites sampled, 13 have recorded a pH (CaCl) of less than 5.5 (Table 1.) A pH less than 5.5 is below the optimal level to prevent the occurrence of subsoil acidification (Soilquality.org.au).

Our project partners have also been busy with soil pH activities.  The links below will take you to: 1) a paper created by PIRSA (South Australia) – Identifying barriers to liming; and, 2)  from Southern Farming Systems in Victoria where they have been conducting lime trials.

PIRSA barriers to use of lime paper 2014

SFS making better liming decisions

Sampling so far has demonstrated that soil acidification is a widespread problem within our region. Due to the long term and short term negative impacts of acidic soils upon our agricultural and environmental systems a pH of less than 5.5 needs to be corrected via the application of agricultural lime at targeted rates – because If you don’t lime it you’re going to lose it.

For further information please call Nick Hill on: 0437 612 140.

Table 1. Historic site average pH. Change over time.
Nyngan Wirrinya Ungarie Condo West Tottenham Euabalong West Lake Cargelligo West
Historic pH (CaCl)(2000)


4.8 4.9 5.2 4.8 5.2 5.7 5.5
Current pH (CaCl) (2014/2015):


5.7 4.4 4.6 4.5 5.0 5.9 5.1

 Table 2 New site average pH: 0-10cm. 2014-2015.
Site pH (CaCl)


Gunning Gap 4.4
Nyngan Nth 4.5
Tottenham Nth 4.7
Tullamore 4.9
Ungarie/Lake Cargelligo 4.9
Tullibigeal 5.0
Weethalle 5.1
Lake Cargelligo West 5.1
Ungarie 5.1
Derriwong 5.2
Alectown 5.2
Condo Wst2 5.3
Lake Cargelligo North 5.3
Condo Nth Boona rd. 5.5
Condo Wst1 5.5
Condo Wst3 6.0
Condo Nth Melrose rd. 6.4