News & Media

Soil sampling determines changes in soil organic carbon

Released on

Released on:
Wednesday, 27. March 2013 - 9:15

Extensive soil sampling across a range of farming systems throughout the Wheatbelt is helping determine changes in soil organic carbon levels over time.

The Department of Agriculture and Food recently completed sampling soil on farm paddocks in and surrounding the shires of Mingenew, Dalwallinu and Wickepin, with the support of funding from the Australian Government’s Carbon Farming Futures - Action on the Ground program.

Department research officer Frances Hoyle said a combination of soil sampling results and site specific information provided by growers would enable the department to assess the impact, time scale and potential value of different soil management methods on soil organic carbon levels.

“We have revisited sites that were originally sampled in 2006 and 2007 to enable us to provide growers with information on how their management strategies during the past five years have affected their soil organic carbon stocks,” Dr Hoyle said.

“In order to effectively assess the impact of various influences on soil organic carbon levels, soil classifications have been taken at each site at the time of sampling and growers have provided five-year paddock management history, rainfall and temperature data.

“In addition to measuring soil organic carbon stocks, a number of other properties that affect soil productivity will be determined, including soil pH, nutrients including available nitrogen, non-wetting and biological function.”

More than 900 samples from160 different locations have been evaluated.

"This work is important because significant changes in total soil organic carbon in Western Australian environments are slow to occur and a significant and continued increase in inorganic matter inputs is required to support them,” Dr Hoyle said.

The results will contribute to regional data on soil organic carbon benchmarks across a range of soils in the South West of Western Australia and will help determine any relationships between climate and farming practices and their impact on soil organic carbon stocks.

Dr Hoyle said soil organic carbon is important in understanding soil health and is an essential component of productive farming systems.  This is especially true where in Western Australia soil organic carbon tends to be low by international farming standards.

Soil organic carbon levels that improve over time as a result of farm management indicate potential production benefits for growers.

The amalgamated regional data will be published on the Soil Quality website at adding to the valuable existing information and providing an estimate for soil organic carbon changes over time.

For more information about the soil testing, contact Dr Hoyle on (08) 9368 3570 or email or department development officer Natalie Hogg on (08) 9690 2081 or email

Media contacts: Jodie Thomson, media liaison     +61 (0)8 9368 3937