RESEARCHERS are spending a lot of time deliberately going over old ground in the Wimmera.
Department of Primary Industries scientists have been re-sampling cropping soils first studied in the late 1960’s.
DPI soils research scientist Nathan Robinson said the samples were essentially time capsules that captured the soil condition at the time of collection.
“Early results suggest an increase in soil organic carbon since the sites were first sampled as part of the National Soil Fertility Program more than 40 years ago,” Mr Robinson said.
“The greatest increase is occurring in the top 30 cm.
He said the results would help farmers understand how to improve soil health to maintain agricultural productivity.
“It is well known that soil organic carbon is important for soil structure and it also helps with water retention and nutrients for plant growth.
“Knowing and understanding the changes to soils over time will help producers and industrycapitalise on any benefits, or mitigate the long term effects of any negative changes.
“For example, if soil conditions are changing, should industry redirect investment into breeding species that are better suited to the new conditions?”
He said while the results were promising, more analysis was needed to understand the changes and the implications.
“We really only have two points of measurement here and we don’t know how much these soil properties may have fluctuated over time.
“However, we think conservation practices such as stubble retention and reduction in tillage over the last 40 years may have contributed to the increase in soil carbon.”
The researchers located almost all of the original 50 sites around the region and measured soil properties at 10 cm intervals down to a depth of one metre over one hectare.
Mr Robinson said one of the biggest challenges was finding the original soil sites to resample.
“To get the project underway we first had to make contact with around 40 landholders to see
if we could come back on their land and take soil samples.
“Many of the farms had been passed down a generation or sold over the years but every one of the farmers we contacted came out and worked with our team to relocate the original plots.
“Even some researchers who set up the original trials came back on board and helped us reestablish these trials as monitoring sites.”
Like the landholders, research has also changed a lot over 40 years.
“The analytical methods we use now weren’t available back then, and soil carbon wasn’t even considered as a key soil property to measure.
“New instruments such as Mid Infra Red Spectrometers enable us to measure soil properties that haven’t been tested before. We can also now rapidly assess and predict properties with a very small soil sample.
“We hope to monitor these sites more regularly into the future so we can measure changes in soil properties over time and inform farmers about implications for soil management.”
The DPI program will continue to re-sample major cereal and pasture soils across Victoria over the next 12-18 months in the Mallee, North East and Southern Victoria.
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