Linking and demonstrating soil health outcomes and management practices

Lead organisation & collaborators (if any):

Bass Coast Landcare Network
DSE ecoMarkets
South Gippsland Landcare Network
Westernport Catchments Landcare Network
DPI-Sustainable Landscapes
Report by Dr Timothy Cavagnaro and Ms Kimberley Damsma, Monash University

Contact:

Timothy Cavagnaro
Monash University
E: timothy.cavagnaro@monash.edu

 

Year of study: 2010-2011

Location: 40 farms and reference sites.

Project details

 

Objectives:

Assess the performance of the rapid soil health assessment tool developed by Bass Coast Landcare Network.

Hypotheses:

Soils from 40 farms and reference sites were analysed for a suite of physicochemical properties. These properties were assessed against BCLN’s soil health assessment tool to test its robustness.

Basis of Trial:

A rapid soil health assessment tool

Methods and Measures

Trial design/layout:

At each site a small soil pit (20cm wide x 20cm long x 40cm deep) was dug.

Soil sampling method:

At each site a 20m x 20m plot was established at the centre of the site, which was then divided into four 1-m x 10m plots. In each plot the soil properties were quantified to 10cm depth.

Six soil cores were taken at each 10m x 10m plot using a 10cm auger. Samples from each plot were mixed in the field to provide a composite sample, placed in air-tight bags and stored at 4C. Samples were tested at EAL.

Cores- split into two sub-samples. 1^st sub sample was dried at 105C for 48 hours, the 2^nd was wet-sieved.

Soil tests:

• Plant available P (Colwell test)
• CEC
• Total C (dry combustion method)
• Total N (dry combustion method)
• Carbon/Nitrogen ratio
• Labile C
• Nitrate
• Ammonium
• PMN (anaerobic incubation)
• Potassium (ammonium acetate test)

In addition, at each soil pit the following was noted:

• Depth of organic matter (visual)
• Leaf colour (visual)
• Root depth and development (visual)
• Macro-life (count)
• Earthworm count (count)
• Soil structure (visual)
• Aggregate stability (in field test)
• Soil compaction (in field measurement)
• Soil biology measurement (quantitative testing)

 

Treatment Results:

Carbon was measured across all sites. A summary is shown below (taken from the technical report)

 

Soil health score and soil properties were in a higher range for those sites which were less intensively managed sites.

The assessment tool itself was found to be an effective tool for measuring chemical, biological and physical soil properties. However it should be used with due consideration of the limitations of the method. The sampling effort and sampling time need to also be carefully considered.